Biology, Physiological Basis and Nutritional Requirements

Chapter 1

Abstract

conserving water.

1. Introduction

3

fasting, marine mammals

sibling competition, and litter size [4].

Lactation Strategies and Milk

Maternal investment during lactation is higher than during gestation, and it is the most energetically expensive period in a mammal's life cycle. Pinnipeds (seals, sea lions, fur seals, and walruses) are one of the principal groups of aquatic mammals that are adapted to reside on land and at sea. During lactation they secrete and rapidly transfer lipid-rich and energy-dense milk to the pup, and they rely on land or ice to give birth to and nurse their pups, and as a consequence, foraging at sea and nursing of the young on land are separated by space and time. Lactation strategies in pinnipeds have evolved to meet particular environmental conditions, and because of their worldwide distribution, they have evolved into two main lactation strategies: fasting strategy and foraging strategy. Both strategies rely on energy reserves for the production of energy-dense and nutrient-rich milk. In comparison with the milk of land and marine mammals, the milk of pinniped is characterized by (a) high milk fat concentration and (b) the virtual absence of lactose. These two main differences in the milk composition are a result of the lactation strategies adopted by pinnipeds and their unique lactation physiology in which they need to transfer a high energy-rich milk in a certain period of time while

Keywords: milk, lipid, protein, pinnipeds, pup, seal, sea lion, walrus, foraging,

Maternal investment during lactation is higher than during gestation, and it is the most energetically expensive period in a mammal's life cycle [1, 2]. In early postnatal life, the neonate is unable to feed itself; hence, it has to rely on the mother for its food supply in the form of milk, and this process of milk production is known as lactation [3]. As a consequence of the full dependence on the female during lactation, parental investment will have a direct effect on the growth rate and survival of the nursing offspring. On the other hand, mammal reproductive success will be influenced by parental age, experience and foraging strategies, and food availability; but also by factor associated to the offspring such as time of weaning,

Pinnipeds (seals, sea lions, fur seals, and walruses) are one of the principal groups of aquatic mammals that are adapted to reside on land and at sea [5, 6]. There are three taxonomic groups of pinnipeds, Otariidae, the sea lions and fur seals; Odobenidae, the walrus; and Phocidae, the true seals, and they have adopted

Composition in Pinnipeds

Federico German Riet Sapriza

#### Chapter 1

## Lactation Strategies and Milk Composition in Pinnipeds

Federico German Riet Sapriza

#### Abstract

Maternal investment during lactation is higher than during gestation, and it is the most energetically expensive period in a mammal's life cycle. Pinnipeds (seals, sea lions, fur seals, and walruses) are one of the principal groups of aquatic mammals that are adapted to reside on land and at sea. During lactation they secrete and rapidly transfer lipid-rich and energy-dense milk to the pup, and they rely on land or ice to give birth to and nurse their pups, and as a consequence, foraging at sea and nursing of the young on land are separated by space and time. Lactation strategies in pinnipeds have evolved to meet particular environmental conditions, and because of their worldwide distribution, they have evolved into two main lactation strategies: fasting strategy and foraging strategy. Both strategies rely on energy reserves for the production of energy-dense and nutrient-rich milk. In comparison with the milk of land and marine mammals, the milk of pinniped is characterized by (a) high milk fat concentration and (b) the virtual absence of lactose. These two main differences in the milk composition are a result of the lactation strategies adopted by pinnipeds and their unique lactation physiology in which they need to transfer a high energy-rich milk in a certain period of time while conserving water.

Keywords: milk, lipid, protein, pinnipeds, pup, seal, sea lion, walrus, foraging, fasting, marine mammals

#### 1. Introduction

Maternal investment during lactation is higher than during gestation, and it is the most energetically expensive period in a mammal's life cycle [1, 2]. In early postnatal life, the neonate is unable to feed itself; hence, it has to rely on the mother for its food supply in the form of milk, and this process of milk production is known as lactation [3]. As a consequence of the full dependence on the female during lactation, parental investment will have a direct effect on the growth rate and survival of the nursing offspring. On the other hand, mammal reproductive success will be influenced by parental age, experience and foraging strategies, and food availability; but also by factor associated to the offspring such as time of weaning, sibling competition, and litter size [4].

Pinnipeds (seals, sea lions, fur seals, and walruses) are one of the principal groups of aquatic mammals that are adapted to reside on land and at sea [5, 6]. There are three taxonomic groups of pinnipeds, Otariidae, the sea lions and fur seals; Odobenidae, the walrus; and Phocidae, the true seals, and they have adopted distinctive lactation strategies [6, 7]. They rely on land or ice to give birth and nurse their pups, and as a consequence, foraging at sea and nursing of the young on land are separated by space and time [6, 7]. While staying on the terrestrial environment, for some species, the mother and the pup are vulnerable to potential terrestrial predators; therefore, pinnipeds have evolved strategies to diminish the risk of predation [7, 8]. Other issues that concern the survival of the pup are (1) the buildup of an insulation layer against heat loss and (2) the supply of enough energy to enable the pup to sustain itself during periods of fasting. These issues are tackled by secreting and rapidly transferring lipid-rich and energy-dense milk to the pup [9, 10]. Lactation strategies in pinnipeds have evolved to meet particular environmental conditions, and because of their worldwide distribution, they have evolved into a diversity of lactation strategies [7, 8, 11]. In this chapter the lactation strategies of pinnipeds are described; and the milk composition of pinnipeds and how its composition varies in relation to maternal factors are discussed.

#### 2. Lactation strategies in pinnipeds

#### 2.1 Foraging lactation strategy: sea lions and fur seals (Otariidae)

Otariids have adopted a lactation strategy known as the "foraging lactation strategy" or as "income breeders," and it is characterized by the mother alternating between nursing the pup on land and periods of foraging at sea (Figure 1) [12]. The perinatal period is known as the time period in which the otariid mother stays on land with the pup after giving birth. During this period, which last about a week, the pup-mother bond is established.

> ecosystems [14]. Upwelling zones in the eastern Pacific undergo a negative transition from normal highly rich productivity to profoundly decreased productivity [15]. Pinnipeds which prey at the top of the food chain are severely affected by low food availability, which in turn disrupts normal maternal foraging and attendance

Species Lactation (months) Source Northern fur seal Callorhinus ursinus 3–4 [23, 25, 32] Antarctic fur seal A. gazella 4 [4, 26, 32] South American sea lion Otaria flavescens 5–12 [5, 7] California sea lion Zalophus c. californianus 6–12 [17, 19, 33] South American fur seal A. australis 6–24 [7, 16, 34] Juan Fernandez fur seal A. philippii 7–10 [35] Subantarctic fur seal A. tropicalis 10 [9, 36] Australian fur seal A. pusillus doriferus 11 [30] Guadalupe fur seal A. townsendii 9–11 [32] Steller's sea lion Eumetopias jubatus 11–12 [37–39] New Zealand fur seal A. forsteri 11–12 [7, 40, 41] New Zealand sea lion Phocarctos hookeri 12 [42] Galapagos sea lion Zalophus c. wollebaeki 12 [5, 21] Cape fur seal A. pusillus pusillus 12 [7, 43] Walrus Odobenus rosmarus 12–36 [5, 7, 44] Galapagos fur seal A. galapagoensis 12–36 [7, 21, 32] Australian sea lion Neophoca cinerea 15–18 [1, 2]

During El Niño conditions, changes in the maternal attendance pattern (nursing behavior) and maternal diving behavior of South American fur seals (Arctocephalus australis) have been recorded [18]. Shortage of food availability due to ENSO conditions resulted in low maternal foraging success and prolonged stay at sea searching for food at high-energy cost. Consequently, South American fur seals nursing mothers were unable to replenish their energy reserves to confront the high-energy cost of lactation. California sea lions (Zalophus californianus) responded in a similar manner to ENSO conditions by extending significantly their foraging trips [19], and pup milk intake was lower than in years without El Niño conditions [17]. During years of shortage of krill near South Georgia, lactating Antarctic fur seal (Arctocephalus gazella) females made fewer and longer trips that resulted in decreased mass and growth of pups [4]. The maternal foraging trips doubled in time, and as a consequence, the mortality of pups increased to 32%, 68% which died from malnutrition [20].

Among otariid species they share very similar breeding and lactation strategies (see Figure 1) [7]. In low-latitude otariids, such as Galapagos fur seals, during pregnancy they spend extended periods of foraging at sea in order to store energy in the form of lipid, and then they arrive at the colony 2–3 days before giving birth. Thereafter the mother nurses the pup during the perinatal period (5–10 days), and then she starts her attendance pattern that consists of foraging trips at night and return to the colony in the morning [21]. Foraging trips lasted around 2 days [21], whereas suckling attendance periods lasted from half a day to one and a half days,

patterns, suckling patterns, pup growth, and pup behavior [16, 17].

Duration of lactation period in fur seals, sea lions, and walruses.

Lactation Strategies and Milk Composition in Pinnipeds DOI: http://dx.doi.org/10.5772/intechopen.85386

Table 1.

5

The duration of lactation in otariids ranges from 4 months to 3 years (Table 1) [7] and may have evolved as a consequence to environmental predictability associated with latitude [11]. The predictability and productivity of the marine environment have had a crucial role in shaping the maternal strategies observed in pinnipeds. For instance, in higher latitudes marine productivity is seasonal and radical; however, very predictable. The duration of lactation in pinnipeds is usually short in higher latitudes, whereas in lower latitudes, the seasonal pattern of marine productivity is more constant throughout the year, and as a result, the duration of lactation in pinnipeds is usually longer (Table 1). Notwithstanding, every few years pinniped inhabiting lower latitudes are exposed to unpredictable productivity due to El Niño/La Niña (El Niño Southern Oscillation or ENSO) conditions, [13]. El Niño Southern Oscillation events have a profound effect on climate and ocean

Figure 1. Maternal foraging strategy of otariid seals (from [7]).



#### Table 1.

distinctive lactation strategies [6, 7]. They rely on land or ice to give birth and nurse their pups, and as a consequence, foraging at sea and nursing of the young on land are separated by space and time [6, 7]. While staying on the terrestrial environment, for some species, the mother and the pup are vulnerable to potential terrestrial predators; therefore, pinnipeds have evolved strategies to diminish the risk of predation [7, 8]. Other issues that concern the survival of the pup are (1) the buildup of an insulation layer against heat loss and (2) the supply of enough energy to enable the pup to sustain itself during periods of fasting. These issues are tackled by secreting and rapidly transferring lipid-rich and energy-dense milk to the pup [9, 10]. Lactation strategies in pinnipeds have evolved to meet particular environmental conditions, and because of their worldwide distribution, they have evolved into a diversity of lactation strategies [7, 8, 11]. In this chapter the lactation strategies of pinnipeds are described; and the milk composition of pinnipeds and how its

Lactation in Farm Animals - Biology, Physiological Basis, Nutritional Requirements…

composition varies in relation to maternal factors are discussed.

2.1 Foraging lactation strategy: sea lions and fur seals (Otariidae)

Otariids have adopted a lactation strategy known as the "foraging lactation strategy" or as "income breeders," and it is characterized by the mother alternating between nursing the pup on land and periods of foraging at sea (Figure 1) [12]. The perinatal period is known as the time period in which the otariid mother stays on land with the pup after giving birth. During this period, which last about a week,

The duration of lactation in otariids ranges from 4 months to 3 years (Table 1)

[7] and may have evolved as a consequence to environmental predictability associated with latitude [11]. The predictability and productivity of the marine environment have had a crucial role in shaping the maternal strategies observed in pinnipeds. For instance, in higher latitudes marine productivity is seasonal and radical; however, very predictable. The duration of lactation in pinnipeds is usually short in higher latitudes, whereas in lower latitudes, the seasonal pattern of marine productivity is more constant throughout the year, and as a result, the duration of lactation in pinnipeds is usually longer (Table 1). Notwithstanding, every few years pinniped inhabiting lower latitudes are exposed to unpredictable productivity due to El Niño/La Niña (El Niño Southern Oscillation or ENSO) conditions, [13]. El Niño Southern Oscillation events have a profound effect on climate and ocean

2. Lactation strategies in pinnipeds

the pup-mother bond is established.

Figure 1.

4

Maternal foraging strategy of otariid seals (from [7]).

Duration of lactation period in fur seals, sea lions, and walruses.

ecosystems [14]. Upwelling zones in the eastern Pacific undergo a negative transition from normal highly rich productivity to profoundly decreased productivity [15]. Pinnipeds which prey at the top of the food chain are severely affected by low food availability, which in turn disrupts normal maternal foraging and attendance patterns, suckling patterns, pup growth, and pup behavior [16, 17].

During El Niño conditions, changes in the maternal attendance pattern (nursing behavior) and maternal diving behavior of South American fur seals (Arctocephalus australis) have been recorded [18]. Shortage of food availability due to ENSO conditions resulted in low maternal foraging success and prolonged stay at sea searching for food at high-energy cost. Consequently, South American fur seals nursing mothers were unable to replenish their energy reserves to confront the high-energy cost of lactation. California sea lions (Zalophus californianus) responded in a similar manner to ENSO conditions by extending significantly their foraging trips [19], and pup milk intake was lower than in years without El Niño conditions [17]. During years of shortage of krill near South Georgia, lactating Antarctic fur seal (Arctocephalus gazella) females made fewer and longer trips that resulted in decreased mass and growth of pups [4]. The maternal foraging trips doubled in time, and as a consequence, the mortality of pups increased to 32%, 68% which died from malnutrition [20].

Among otariid species they share very similar breeding and lactation strategies (see Figure 1) [7]. In low-latitude otariids, such as Galapagos fur seals, during pregnancy they spend extended periods of foraging at sea in order to store energy in the form of lipid, and then they arrive at the colony 2–3 days before giving birth. Thereafter the mother nurses the pup during the perinatal period (5–10 days), and then she starts her attendance pattern that consists of foraging trips at night and return to the colony in the morning [21]. Foraging trips lasted around 2 days [21], whereas suckling attendance periods lasted from half a day to one and a half days,

the length of which is related to the age of the pup [22]. The tropical Galapagos fur seals have the longest lactation period in otariids that lasts from 1 to 3 years (Table 1). Their conspecific, the Galapagos sea lions (Zalophus californianus wollebaeki), attended their pups almost every day and foraged during the day and returned at night [21].

In comparison with otariids inhabiting low latitude, species with high-latitude distribution have shorter lactations period (e.g., Antarctic fur seals, northern fur seals Callorhinus ursinus, and subantarctic fur seals Arctocephalus tropicalis (see Table 1)). Antarctic and northern fur seals wean their pups at the age of 4 months, while subantarctic fur seals wean their pups at the age of 10 months (Table 1) [5]. Pregnant Antarctic fur seals arrive at the colony 2 days prior parturition, and their perinatal period lasts for about 5–7 days, and then the mother alternates foraging at sea for 3–5 days with attendance periods of 3–10 days [23, 24]. Similarly, pregnant northern fur seals arrive to the colony 12 hours to 2 days prior to the birth and nurse their pup during the 6–7 days perinatal period before commencing their first postpartum foraging trip that could last 4–7 days [23, 25].

The mean duration of foraging trips of lactating northern fur seals lasted for 6–8 days and was longer than in Antarctic fur seals, while their attendance period lasted from 36 hours to 2 and a half days. Interestingly, subantarctic fur seals have one of the longest attendance pattern recorded in fur seals. The females arrive ashore 1–2 days prepartum and then spend 8 days nursing the newborn, thereafter alternating long foraging trips of 11–23 days with long maternal attendance periods ashore of up to 4 days [26, 27]. This attendance pattern is constant throughout the whole period of lactation and until the pup is weaned at 10 months of age (Table 1) [26].

In conclusion, otariids inhabiting low latitudes are exposed to a marine environment with very unpredictable low food productivity, while otariid mothers raising their pups at high latitudes have to deal with a more predictable marine environment with high seasonal productivity.

Given the degree of the predictability of the food productivity in the marine environment, one may expect to observe shorter lactation duration in subpolar otariid species due to the short high-productivity seasonal period. However, some species data contradict this argument and cannot be sustained.

Therefore, it could be argued that the duration of lactation in otariids might be a result of the seasonal availability and predictability of food sources, while foraging trip duration and rate of energy transfer are determined by the distance from the breeding site ashore to the food source at sea [6]. Some investigators have raised the question whether milk composition in otariids is directly or indirectly influenced by interspecific differences in the duration of foraging trips at sea [9, 10, 21, 28–31].

#### 2.2 Fasting lactation strategy: seals (Phocidae)

Phocid maternal strategies differ from that of the otariids, mainly by a shorter lactation period and maternal fasting throughout the whole lactation period (Figure 2 and Table 2). Phocids have adopted a lactation strategy known as the fasting lactation strategy making them capital breeders [12]; however, not all phocid species are embedded into this strategy. Pregnant phocid females arrive at haul-out sites a few days before pupping, and when nursing is completed, the pup is abruptly weaned (Figure 2) [5]. Phocid seals that breed on pack or fast ice are known as pagophilic seals, while seals that breed on dry land are known as land-whelping seals [7].

Ice-breeding seals or pagophilic seals (breed on pack or fast ice) [7] have evolved remarkable breeding and lactation strategies in order to reduce predation pressure.

In order to do so, phocids have shortened the duration of lactation, and they have inhabited higher-latitude breeding substrate in which terrestrial predator area is

Duration of lactation (days) in true seals (phocids) breeding on three different substrates: pack-ice, fast-ice,

Diagram of the breeding and lactation strategy of true seals, phocids, known also as the fasting strategy, and

Species Lactation period (days) Source

Hooded seal Cystophora cristata 4 [48] Harp seal Phoca groenlandica 12–13 [49] Crabeater seal Lobodon carcinophagus 14–21 [50] Bearded seal Erignathus barbatus 12–24 [51] Gray seal Halichoerus grypus 16 [5] Caspian seal Phoca caspica 21 [52] Ribbon seal Phoca fasciata 21–28 [53] Spotted seal Phoca largha 28 [5, 54] Leopard seal Hydrurga leptonyx 30 [55]

Weddell seal Leptonychotes weddellii 35–42 [56] Ringed seal Phoca hispida 36–41 [57] Baikal seal Phoca sibirica 60–75 [58]

Harbor seal P. v. richardsi 21–35 [52] Southern elephant seal Mirounga leonine 23 [59, 60] Northern elephant seal M. angustirostris 28 [61, 62] Harbor seal Phoca vitulina vitulina 28–42 [63] Harbor seal P. v. concolor 33 [52] Hawaiian monk seal Monachus schauinslandi 42 [64, 65] Mediterranean monk seal M. monachus 42–49 [65, 66] Harbor seal P. v. Stejnegeri 90 [52]

almost nonexistent [7]. However, fast-ice phocids such as ringed seals

Figure 2.

capital breeders [7].

Lactation Strategies and Milk Composition in Pinnipeds DOI: http://dx.doi.org/10.5772/intechopen.85386

Pack ice

Fast ice

Land

Table 2.

and land.

7

Lactation Strategies and Milk Composition in Pinnipeds DOI: http://dx.doi.org/10.5772/intechopen.85386

#### Figure 2.

the length of which is related to the age of the pup [22]. The tropical Galapagos fur

In comparison with otariids inhabiting low latitude, species with high-latitude distribution have shorter lactations period (e.g., Antarctic fur seals, northern fur seals Callorhinus ursinus, and subantarctic fur seals Arctocephalus tropicalis (see Table 1)). Antarctic and northern fur seals wean their pups at the age of 4 months, while subantarctic fur seals wean their pups at the age of 10 months (Table 1) [5]. Pregnant Antarctic fur seals arrive at the colony 2 days prior parturition, and their perinatal period lasts for about 5–7 days, and then the mother alternates foraging at sea for 3–5 days with attendance periods of 3–10 days [23, 24]. Similarly, pregnant northern fur seals arrive to the colony 12 hours to 2 days prior to the birth and nurse their pup during the 6–7 days perinatal period before commencing their first post-

The mean duration of foraging trips of lactating northern fur seals lasted for 6–8 days and was longer than in Antarctic fur seals, while their attendance period lasted from 36 hours to 2 and a half days. Interestingly, subantarctic fur seals have one of the longest attendance pattern recorded in fur seals. The females arrive ashore 1–2 days prepartum and then spend 8 days nursing the newborn, thereafter alternating long foraging trips of 11–23 days with long maternal attendance periods ashore of up to 4 days [26, 27]. This attendance pattern is constant throughout the whole period of lactation and until the pup is weaned at 10 months of age

In conclusion, otariids inhabiting low latitudes are exposed to a marine environment with very unpredictable low food productivity, while otariid mothers raising their pups at high latitudes have to deal with a more predictable marine environ-

Given the degree of the predictability of the food productivity in the marine environment, one may expect to observe shorter lactation duration in subpolar otariid species due to the short high-productivity seasonal period. However, some

Therefore, it could be argued that the duration of lactation in otariids might be a result of the seasonal availability and predictability of food sources, while foraging trip duration and rate of energy transfer are determined by the distance from the breeding site ashore to the food source at sea [6]. Some investigators have raised the question whether milk composition in otariids is directly or indirectly influenced by interspecific differences in the duration of foraging trips at sea [9, 10, 21, 28–31].

Phocid maternal strategies differ from that of the otariids, mainly by a shorter lactation period and maternal fasting throughout the whole lactation period (Figure 2 and Table 2). Phocids have adopted a lactation strategy known as the fasting lactation strategy making them capital breeders [12]; however, not all phocid species are embedded into this strategy. Pregnant phocid females arrive at haul-out sites a few days before pupping, and when nursing is completed, the pup is abruptly weaned (Figure 2) [5]. Phocid seals that breed on pack or fast ice are known as pagophilic seals, while seals that breed on dry land are known as

Ice-breeding seals or pagophilic seals (breed on pack or fast ice) [7] have evolved remarkable breeding and lactation strategies in order to reduce predation pressure.

species data contradict this argument and cannot be sustained.

2.2 Fasting lactation strategy: seals (Phocidae)

land-whelping seals [7].

6

seals have the longest lactation period in otariids that lasts from 1 to 3 years (Table 1). Their conspecific, the Galapagos sea lions (Zalophus californianus wollebaeki), attended their pups almost every day and foraged during the day and

Lactation in Farm Animals - Biology, Physiological Basis, Nutritional Requirements…

partum foraging trip that could last 4–7 days [23, 25].

returned at night [21].

(Table 1) [26].

ment with high seasonal productivity.

Diagram of the breeding and lactation strategy of true seals, phocids, known also as the fasting strategy, and capital breeders [7].


#### Table 2.

Duration of lactation (days) in true seals (phocids) breeding on three different substrates: pack-ice, fast-ice, and land.

In order to do so, phocids have shortened the duration of lactation, and they have inhabited higher-latitude breeding substrate in which terrestrial predator area is almost nonexistent [7]. However, fast-ice phocids such as ringed seals

(Phoca hispida) are preyed by polar bear and arctic fox and have avoided predation pressure by giving birth and nursing their pups in snow and ice dens [45, 46]. If predation is nonexistent or basically avoided by choice of breeding site, then any variations in the maternal strategies must be related to other ecological factors such as stability of breeding substrate.

There are some advantages and disadvantages for phocid breeding on ice packs (ice floating on the sea surface). Seals have a rapid access to deep waters; however, ice packs provide little shelter and are an unstable substrate at the mercy of wind and sea surface currents that could drift away the ice pack separating the mother and pup. As a consequence of the instability of the pack-ice breeding, pagophilic seals have the shortest lactation period in pinnipeds (4–30 days) [5, 7, 47]. On the contrary, in more stable environments such fast-ice or land, seals are able to extend the duration of the lactation period (36–75 days).

The shortest lactation period in pack-ice-breeding species has been reported in the hooded seal, Cystophora cristata, that nurses pups for only 4 days [47], and the harp seal, Phoca groenlandica, for 12–13 days [67], while the longest lactation period has been recorded in seals that breed on fast-ice and land (Table 2). In comparison with the duration of lactation in Baikal seals and the Mediterranean monk seals, southern (Mirounga leonina) and northern elephant seals (Mirounga angustirostris) have significantly shorter periods of 21 and 28 days, respectively (Table 2). The short lactation duration described in phocid in comparison with otariids and maternal fast during the nursing period influence the milk composition and the dynamics of energy transfer from mother to pup. Moreover, the high milk energy content in phocid could be a result of the short lactation duration in which a large amount of energy in the form of milk lipid and protein is transferred to the nursing pup in a limited time.

Two distinctive lactation strategies have been observed in ice-breeding seals (e.g., hooded seals and gray seals, Halichoerus grypus). In the first lactation strategies, seal mothers nurse their pup with very energy-rich milk during a very short lactation period (Tables 2 and 3). This lactation strategy involves the pup being very inactive and in most cases does not enter the water for many weeks, and they are abruptly weaned, and then the pup must withstand a long postweaning fasting period [68].

The second lactation strategy is observed in bearded seals Erignathus barbatus and ringed seals Phoca hispida and has the longest lactation duration among icebreeding phocids. In addition, nursing mothers do not fast entirely during the lactation period, the energy content in milk is lower, and pups are more active. It was argued that only otariids have evolved a foraging lactation strategy in which lactating females have pup attendance periods on land alternated with foraging trips at sea.

that can be stored. The demand of energy from her limited body's stored reserves (blubber) to produce milk and to maintain her own energy needs may not be

Species Milk composition (%)

47.15b 55.4c

43.7b

25.1<sup>b</sup>

—

51.9 4.9<sup>b</sup> 52.3 6.0<sup>c</sup>

> 47.7b 47.9<sup>c</sup>

\*Values estimated from regression equations (see Arnould and Hindell) [30]

Australian sea lion<sup>+</sup> [2, 28] 28.35<sup>a</sup>

Lactation Strategies and Milk Composition in Pinnipeds DOI: http://dx.doi.org/10.5772/intechopen.85386

California sea lion [17] 31.7a

Galapagos sea lion [21] 32.4<sup>a</sup>

Galapagos fur seal [21, 83] 29.4 5.9<sup>a</sup>

Subantarctic fur seal [10] 45.0 3.7a

Australian fur seal\* [30] 32.7<sup>a</sup>

Lipid Water Protein Sugar Ash

9.9 2.5 — —

> 8.5 —

9 —

9.9 1.4<sup>a</sup> 14.0 0.9<sup>b</sup>

13.4 1.4<sup>a</sup> 11.6 1.3b 11.5 1.2<sup>c</sup>

> 9.9<sup>a</sup> 11.0b 12.3<sup>c</sup>

— — —

0.3 —

> — —

0.1 —

> — — —

> — — —

0.9 0.3 — —

> — —

> — —

0.9 0.1 —

> — — —

0.7 0.1 — —

56.9 9.9 — —

> 59.0 —

> > — —

> > — —

40.7 4.5<sup>a</sup> 33.3 4.0<sup>b</sup> 33.3 4.9<sup>c</sup>

> 54.6<sup>a</sup> 39.1<sup>b</sup> 44.3<sup>c</sup>

New Zealand sea lions [82] 21.3 8.1 67.9 8.8 9.4 2.4 0.4 0.48 0.06

Guadalupe fur seal [10] 41 — ——— Juan Fernandez fur seal [29] 41.4 5.8 — 11.9 2.0 1.2 0.4 0.7 0.1

South American fur seal [84] 36.5 4.2 — 9.1 0.8 — —

Cape fur seal [85] 23.2<sup>a</sup> 8.2 58.1 6.8 10.8 1.2 — 2.0 0.6 Northern fur seal [7, 86] 45.6 36.4 12.4 0.1 0.6 Antarctic fur seal [3, 9] 39.8 6.7 41.3 9.3 18.1 5.8 — 0.7 0.1 Walrus [79] 24.1 59.9 7.8 — 0.59

Steller sea lion [37] 24 — ——— South American sea lion [81] 38.6 3.1a 48.9 3.1 11.1 1.2 — 0.8 0.1

Taken into consideration the small maternal body size of harbor seals, it is very likely that at least half of the phocid species with similar small body size may have adopted the "otariid-like" maternal foraging cycle [73]. There is evidence that shows that lactating harbor seal started to forage at sea when the gain of energy, to restore energy reserves, was highest and the uncertainty of pup mortality was the lowest [73]. Maternal body size has been shown to play an important role in shaping lactation strategies in pinnipeds [8]. For instance small body size phocids, cannot store enough energy in the form of blubber (lipid) to support the high cost of lactation, and thus, there are physiological limits that are interacting and influenc-

enough [6, 72–74].

a

b

c

+

9

Table 3.

Early lactation

Mid lactation

Late lactation

Values were averaged.

Milk composition of otariids and walrus.

ing their lactation strategy [6, 69].

Research about the energetics and diving behavior of harbor seals (Phoca vitulina) has demonstrated that maternal body mass has important consequences for lactation strategies in phocid species and that some phocids have adopted an "otariid like-lactation strategy" [69]. This may in fact suggest that ice-breeding seals such as bearded and ringed seals, with long lactation duration and lower energy-rich milk, are unable to sustain lactation while fasting. There is data that support the hypothesis that these seals have adopted an "otariid-like" maternal foraging cycle [57, 70, 71]. An otariid-like foraging cycle behavior may have evolved in small body size phocids, such as the harbor seal, as a result of depletion of maternal body energy reserves in the form of lipid during the lactation period [6]. The maternal body size of harbor seals is slightly larger than most otariids, suggesting that the body size may be limiting the amount of energy reserves (lipid)


#### Lactation Strategies and Milk Composition in Pinnipeds DOI: http://dx.doi.org/10.5772/intechopen.85386

Early lactation

(Phoca hispida) are preyed by polar bear and arctic fox and have avoided predation pressure by giving birth and nursing their pups in snow and ice dens [45, 46]. If predation is nonexistent or basically avoided by choice of breeding site, then any variations in the maternal strategies must be related to other ecological factors such

Lactation in Farm Animals - Biology, Physiological Basis, Nutritional Requirements…

There are some advantages and disadvantages for phocid breeding on ice packs (ice floating on the sea surface). Seals have a rapid access to deep waters; however, ice packs provide little shelter and are an unstable substrate at the mercy of wind and sea surface currents that could drift away the ice pack separating the mother and pup. As a consequence of the instability of the pack-ice breeding, pagophilic seals have the shortest lactation period in pinnipeds (4–30 days) [5, 7, 47]. On the contrary, in more stable environments such fast-ice or land, seals are able to extend

The shortest lactation period in pack-ice-breeding species has been reported in the hooded seal, Cystophora cristata, that nurses pups for only 4 days [47], and the harp seal, Phoca groenlandica, for 12–13 days [67], while the longest lactation period has been recorded in seals that breed on fast-ice and land (Table 2). In comparison with the duration of lactation in Baikal seals and the Mediterranean monk seals, southern (Mirounga leonina) and northern elephant seals (Mirounga angustirostris) have significantly shorter periods of 21 and 28 days, respectively (Table 2). The short lactation duration described in phocid in comparison with otariids and maternal fast during the nursing period influence the milk composition and the dynamics of energy transfer from mother to pup. Moreover, the high milk energy content in phocid could be a result of the short lactation duration in which a large amount of energy in the form of milk lipid and protein is transferred to the nursing pup in a

Two distinctive lactation strategies have been observed in ice-breeding seals (e.g., hooded seals and gray seals, Halichoerus grypus). In the first lactation strategies, seal mothers nurse their pup with very energy-rich milk during a very short lactation period (Tables 2 and 3). This lactation strategy involves the pup being very inactive and in most cases does not enter the water for many weeks, and they are abruptly weaned, and then the pup must withstand a long postweaning fasting

The second lactation strategy is observed in bearded seals Erignathus barbatus and ringed seals Phoca hispida and has the longest lactation duration among icebreeding phocids. In addition, nursing mothers do not fast entirely during the lactation period, the energy content in milk is lower, and pups are more active. It was argued that only otariids have evolved a foraging lactation strategy in which lactating females have pup attendance periods on land alternated with foraging

Research about the energetics and diving behavior of harbor seals (Phoca vitulina) has demonstrated that maternal body mass has important consequences for lactation strategies in phocid species and that some phocids have adopted an "otariid like-lactation strategy" [69]. This may in fact suggest that ice-breeding seals such as bearded and ringed seals, with long lactation duration and lower energy-rich milk, are unable to sustain lactation while fasting. There is data that support the hypothesis that these seals have adopted an "otariid-like" maternal foraging cycle [57, 70, 71]. An otariid-like foraging cycle behavior may have evolved in small body size phocids, such as the harbor seal, as a result of depletion of maternal body energy reserves in the form of lipid during the lactation period [6].

The maternal body size of harbor seals is slightly larger than most otariids,

suggesting that the body size may be limiting the amount of energy reserves (lipid)

as stability of breeding substrate.

limited time.

period [68].

trips at sea.

8

the duration of the lactation period (36–75 days).

b Mid lactation

c Late lactation

\*Values estimated from regression equations (see Arnould and Hindell) [30]

+ Values were averaged.

#### Table 3.

Milk composition of otariids and walrus.

that can be stored. The demand of energy from her limited body's stored reserves (blubber) to produce milk and to maintain her own energy needs may not be enough [6, 72–74].

Taken into consideration the small maternal body size of harbor seals, it is very likely that at least half of the phocid species with similar small body size may have adopted the "otariid-like" maternal foraging cycle [73]. There is evidence that shows that lactating harbor seal started to forage at sea when the gain of energy, to restore energy reserves, was highest and the uncertainty of pup mortality was the lowest [73]. Maternal body size has been shown to play an important role in shaping lactation strategies in pinnipeds [8]. For instance small body size phocids, cannot store enough energy in the form of blubber (lipid) to support the high cost of lactation, and thus, there are physiological limits that are interacting and influencing their lactation strategy [6, 69].

Northern and southern elephant seals have a similar breeding pattern, and a wide variety of social behavior traits (age, sex, and season) are a result of welldefined seasonal cycles and making of large colonies. Within the group of landwhelping seals, elephant seals have one of the shortest lactation periods, lasting 23 days in southern elephant seals and 28 days in northern elephant seals. During this period the pup has a rapid growth rate [59, 75], and it is followed by a long postweaning fasting period (2–3 months) [76]. Notwithstanding during this period, male pup steals milk from other mothers in order to grow bigger, and this is driven by a marked sexual dimorphism in elephant seals, i.e., there is a selective advantage in increased size in males (Figure 3).

2.3 Aquatic lactation strategy: Odobenidae (walrus)

Lactation Strategies and Milk Composition in Pinnipeds DOI: http://dx.doi.org/10.5772/intechopen.85386

weaned mass and the survival chances of the pup [44].

Harp seal [93–96] 35.8 1.8a

Hooded seal [7, 97] 56.3a

Gray seal [51, 98] 39.8 2.8<sup>a</sup>

Southern elephant seal [59, 101] 16.1 7.0<sup>a</sup>

Northern elephant seal [61] 24a

Crabeater seal [102, 103] 35<sup>a</sup>

Milk composition in true seal, phocids.

a

b

c

11

Early lactation

Mid lactation

Late lactation

Table 4.

Species Milk composition (%)

35.4b 57.1 0.5<sup>c</sup>

> 61.0<sup>b</sup> 61.1<sup>c</sup>

55.6 1.6b 60.0 1.86c

39.5 15.2b

47<sup>b</sup> 54c

50<sup>b</sup>

Lipid Water Protein Sugar Ash

10.4 0.5<sup>a</sup> 7.7 0.2c —

> 6.2a 4.7<sup>b</sup> 5.1<sup>c</sup>

11.2 0.8<sup>a</sup> 9.4 0.14b,c —

12.6 2.3<sup>a</sup> 10.7 2.8c

> 5–12 — —

10<sup>a</sup> 10.8 0.69–0.79<sup>a</sup> 0.65<sup>c</sup> —

> 0.86<sup>a</sup> 1.05<sup>b</sup> 0.99<sup>c</sup>

0.7<sup>a</sup> 0.8b,c —

0.28 0.10 —

> <0.25 — —

1.1–1.9 —

0.61 — —

0.86 — —

0.69 — —

> — —

> — — —

1.04<sup>a</sup> 0.93<sup>b</sup>

51.4 1.8a 32.4 0.4<sup>c</sup> —

> 49.8 — —

45.0 2.1<sup>a</sup> 3.0 1.4<sup>b</sup> 28.6 1.3c

> 70a 33<sup>c</sup>

> 75a 35<sup>c</sup> —

> > — —

Bearded seal [7, 97] 49.5 46.4 6.8 0.05 0.6 Weddell seal [99, 100] 53.6a 43.6 14.1 0.02 — Harbor seal [6] 50 — — ——

Recapitulating, a third lactation strategy, known as aquatic strategy, has been described in pinnipeds that differ from that of the capital (phocids) and income breeders (otariids). In the northern hemisphere, in high latitudes, two subspecies of walruses occur, namely, the Atlantic walrus, Odobenus rosmarus rosmarus, and the Pacific walrus O. r. divergens [77]. Walruses are most social among pinnipeds species, and they are usually found in a group on ice floes hauling out, resting, molting, and whelping [78]. In fact, the migration pattern of mother pups pairs is associated with ice movement [79]. At some point in their reproductive cycle, all pinniped species need to return to land or ice to give birth and nurse their pup, and eventually the mother and the pup venture into the sea to search for food. However, walruses have adopted an aquatic lactation strategy in which the mother gives birth to the pup on ice floes, and after the perinatal period (few days), the mother returns to the sea with the pup. Nursing of the pup occurs in the water and on land and ice, and when the mother dives to search for food, the pup remains at the surface [44]. The lactation period lasts for 2 years, and at the age of 5 months, the pup starts to consume solid food, mainly benthic invertebrates [80]. Fisher and Stewart [80] suggested that the long duration of lactation might be associated with the specific mode of feeding of walruses. The main prey of walruses are bivalves (benthic fauna) that inhabit the bottom of the sea [80]. In early stages of lactation, the pup must learn how to dive and search for food at the bottom of the sea, and this may explain the extended duration of lactation that apparently should increase the

A mentioned before, small maternal body size phocids species have adopted alternative "otariid-like" lactation strategies within their group. In this context it may be possible to raise the question what are the factor/s or selective pressure that are governing the maternal strategies in phocids and are they the same as in otariids.

The influence of latitude on the lactation strategies, as described in otariids, have not been suggested for phocids. However, there are environmental factors associated with latitude that may have influenced the evolution of lactation strategies in phocids [11]. The duration of lactation in phocids has evolved, driven by the selective pressure of the breeding substrate and the cost of milk production, and to some extent predation [11]. However, the argument about predation pressure may not apply for most land-breeding phocids since they breed on predator-free islands. Consequently, there must be other selective pressures, apart from the breeding substrate, that caused the shortening of the lactation duration in phocids [11].

In conclusion, the lactation strategy adopted by most phocids is quite unique. Their lactation period is very short in comparison with otariids, and they fast for the entire lactation. As a result they need to store enough energy in body reserves (blubber) in order to produce the most nutrient-rich, energy-dense milk among mammal species. Due to phocid large maternal body size, they store large amount of energy and can withstand the high cost of lactation while fasting. However, small body size phocids such as harbor seals are unable to withstand the cost of lactation due to body nutrient depletion and have adopted an "otariid-like" lactation strategy in which the mother forages at sea.

Figure 3. Fasting lactation strategy in phocids, the northern elephant seals Mirounga angustirostris [7].

Northern and southern elephant seals have a similar breeding pattern, and a wide variety of social behavior traits (age, sex, and season) are a result of welldefined seasonal cycles and making of large colonies. Within the group of landwhelping seals, elephant seals have one of the shortest lactation periods, lasting 23 days in southern elephant seals and 28 days in northern elephant seals. During this period the pup has a rapid growth rate [59, 75], and it is followed by a long postweaning fasting period (2–3 months) [76]. Notwithstanding during this period, male pup steals milk from other mothers in order to grow bigger, and this is driven by a marked sexual dimorphism in elephant seals, i.e., there is a selective advantage

Lactation in Farm Animals - Biology, Physiological Basis, Nutritional Requirements…

A mentioned before, small maternal body size phocids species have adopted alternative "otariid-like" lactation strategies within their group. In this context it may be possible to raise the question what are the factor/s or selective pressure that are governing the maternal strategies in phocids and are they the same as in otariids. The influence of latitude on the lactation strategies, as described in otariids, have not been suggested for phocids. However, there are environmental factors associated with latitude that may have influenced the evolution of lactation strategies in phocids [11]. The duration of lactation in phocids has evolved, driven by the selective pressure of the breeding substrate and the cost of milk production, and to some extent predation [11]. However, the argument about predation pressure may not apply for most land-breeding phocids since they breed on predator-free islands. Consequently, there must be other selective pressures, apart from the breeding substrate, that caused the shortening of the lactation duration in phocids [11]. In conclusion, the lactation strategy adopted by most phocids is quite unique. Their lactation period is very short in comparison with otariids, and they fast for the entire lactation. As a result they need to store enough energy in body reserves (blubber) in order to produce the most nutrient-rich, energy-dense milk among mammal species. Due to phocid large maternal body size, they store large amount of energy and can withstand the high cost of lactation while fasting. However, small body size phocids such as harbor seals are unable to withstand the cost of lactation due to body nutrient depletion and have adopted an "otariid-like" lactation strategy

in increased size in males (Figure 3).

in which the mother forages at sea.

Fasting lactation strategy in phocids, the northern elephant seals Mirounga angustirostris [7].

Figure 3.

10

#### 2.3 Aquatic lactation strategy: Odobenidae (walrus)

Recapitulating, a third lactation strategy, known as aquatic strategy, has been described in pinnipeds that differ from that of the capital (phocids) and income breeders (otariids). In the northern hemisphere, in high latitudes, two subspecies of walruses occur, namely, the Atlantic walrus, Odobenus rosmarus rosmarus, and the Pacific walrus O. r. divergens [77]. Walruses are most social among pinnipeds species, and they are usually found in a group on ice floes hauling out, resting, molting, and whelping [78]. In fact, the migration pattern of mother pups pairs is associated with ice movement [79]. At some point in their reproductive cycle, all pinniped species need to return to land or ice to give birth and nurse their pup, and eventually the mother and the pup venture into the sea to search for food. However, walruses have adopted an aquatic lactation strategy in which the mother gives birth to the pup on ice floes, and after the perinatal period (few days), the mother returns to the sea with the pup. Nursing of the pup occurs in the water and on land and ice, and when the mother dives to search for food, the pup remains at the surface [44].

The lactation period lasts for 2 years, and at the age of 5 months, the pup starts to consume solid food, mainly benthic invertebrates [80]. Fisher and Stewart [80] suggested that the long duration of lactation might be associated with the specific mode of feeding of walruses. The main prey of walruses are bivalves (benthic fauna) that inhabit the bottom of the sea [80]. In early stages of lactation, the pup must learn how to dive and search for food at the bottom of the sea, and this may explain the extended duration of lactation that apparently should increase the weaned mass and the survival chances of the pup [44].


b Mid lactation

c Late lactation

### Table 4.

In comparison with the milk of pinniped species, the milk produced by walruses contains the lowest lipid and protein concentration (Table 4). The low-energy content of milk may be explained by the very long duration of lactation, and hence, there is less pressure in terms of maternal energy reserve depletion and for rapid transfer of energy-rich milk to the pup. Walruses inhabit the same marine environment as pagophilic phocid seals and thus must face the same high thermoregulatory needs and predation pressure. Walruses have evolved an aquatic lactation strategy in which foraging at sea and nursing their pup are not spatially and temporally separated. As a consequence they are able to extend their lactation period, lower the maternal cost (nutrient depletion), and lower pup mortality.

total protein in phocid milk [87, 107], whereas in otariids, such as northern fur seals and Galapagos fur seals, casein accounted for 52 and 75%, respectively [83, 86, 108]. Moreover, pinniped milk has slightly higher amino acid concentration than in the milk of terrestrial mammal. However, both pinniped mammal species have similar range values for the proportion of total essential amino acids, total branched-chain amino acids, total sulfur amino acids, and most individual amino acids in relation to the total amino acids [83, 109]. Furthermore, the amino acid pattern and total amino acid concentration of milk were affected by stage of lactation in terrestrial mammals but not in pinnipeds [83, 109, 110]. This is contrary to Davis et al. [110] study that suggested that changes in amino acid pattern and total amino acid concentration during lactation were unrelated to phylogenetic order. There are a great variety of saccharides in milk [111, 112]; however, lactose (disaccharide) is the dominant sugar, and it is synthesized in the mammary gland. Notwithstanding, the milk of marine mammals contains only traces or no lactose at all. For instance, in human milk more than 100 oligosaccharides or saccharides that contain three or more monosaccharide residues have been observed. The chemical structures of around 80 have been reported [113]. In comparison with measurements of the concentrations of milk fat and protein, carbohydrates have been given little attention in pinnipeds, but data have been reported for Australian

Lactation Strategies and Milk Composition in Pinnipeds DOI: http://dx.doi.org/10.5772/intechopen.85386

fur seals and hooded seal [114], harp seal [106], crabeater seal (Lobodon

lactation period in otariids species is not available.

quently loss of water.

13

carcinophagus) [102, 115], and Arctic harbor seal (Phoca vitulina vitulina) [116]. It has been reported that phocid milk contains several oligossacharides of unknown structure, low concentrations of free lactose, and traces of glucose and galactose [102, 114, 115]. In the milk of most mammals apart from pinnipeds and cetaceans, lactose is the predominant component of carbohydrates [117]. As a consequence, pinnipeds have among the lowest milk carbohydrate concentration of any mammal. The chemical characterization of carbohydrates in hooded seal, crabeater seal and Australian fur seals, California sea lions, and northern fur seals has revealed that, unlike phocids, otariid milk does not contain free reducing saccharides or lactose [86, 102, 105, 106, 114, 118]. The biological function of milk oligosaccharides in phocids may be similar to that in terrestrial mammals, but this does not apply to otariids since they produce milk without free saccharides [114]. The concentration of carbohydrates in Antarctic fur seal milk decreases significantly throughout lactation [3], and similar data on the specific carbohydrates concentrations during the

Lactose is a carbohydrate usually present in the milk of mammals but is lacking

Furthermore, the virtual absence of lactose in milk could be associated to the inability of otariid to digest this carbohydrate. Most mammalian species are able to digest lactose through intestinal lactase activity, but some pinniped species' intestinal disaccharidases appear to be low [120, 122, 123]. For instance, lactose intolerance in California sea lions pups and adults has been demonstrated [124]; however,

or virtually absent in pinniped milk. The protein α-lactalbumin is an essential component of the lactose synthetase complex, and it is not present in otariid. However, low activity of the protein α-lactalbumin in the milk of northern fur seals have been reported [119] which suggests an altered α-lactalbumin molecule with low biological activity rather than its complete absence in the milk of otariids [120]. The absence of lactose in otariids milk and the presence of traces of lactose in phocids milk are consequences for the need of water conservation [84] and consequently associated to the evolutionary history of pinniped. The need for water conservation is directly related to the secretion of lactose into milk. The later causes movement of water to maintain isotonicity with other body fluids [121] and conse-

#### 3. Milk composition in pinnipeds and other mammals

Milk is secreted by the mammary glands, and it is a complex fluid that contains five main components, water, lipids, proteins, sugars, and minerals [87–89]. Several of these can be divided further into more specific components. The concentrations of all the components in milk may vary both between species and within species at different stages of lactation and under different nutritional and environmental condition. Extensive reviews of the comparative composition of milk across species can be found elsewhere [87, 90–92]. The milk of pinnipeds differs substantially from other mammals in (a) high-fat concentration in milk and (b) virtual absence of lactose. These differences are a consequence of their lactation strategies and physiology in which the rapid transfer of energy-rich milk and the conservation of water are essential.

Pinnipeds are a group of mammals that produce the richest energy-dense milk, and fat is the major contributor to the energy content of milk. Milk fat concentration varies considerably between pinnipeds species and within species (see Tables 3 and 4). Overall phocids produce milk with a higher concentration of fat than otariids although some otariids produce milk with high-fat concentrations (Tables 3 and 4). In most species the milk fat concentration varies in response to suckling, and as the mammary gland is being emptied, pinnipeds are not an exception. As in other mammals, milk fat concentration is influenced by stage of lactation and by nutritional status [88]; however, it is not clear how the latter is mediated in pinnipeds. This and other factors that affect milk composition in pinnipeds and in particular milk fat concentration are discussed further (see subsection factors that influence the milk composition) in this chapter.

Milk proteins are either caseins or whey proteins, and the kind and number of protein varies significantly between mammal species [104]. Proteins that are most common in milk are caseins, blood serum albumin, immunoglobulins, and alphalactalbumin, and the beta-lactoglobulin family is only found in the milk of ruminants and some species of artiodactyls [104].

Protein such as casein has a nutritional function and is a source of amino acids for the suckling offspring. There is some knowledge about milk proteins and their function in terrestrial mammal; therefore, little can be suggested for homologous proteins found in the milk of pinniped. A whey protein, such as alpha-lactalbumin, has not been found in otariid milk and is practically absent in phocid milk [84, 105, 106]. The protein alpha-lactalbumin is crucial for biosynthesis of lactose in milk, and therefore, the absence of lactose in pinniped milk has been associated with the lack of this protein [86]. By comparison with bovine milk, casein micelles found in northern fur seals milk were significantly larger, but the reason for this has not been addressed [86]. Caseins have been reported to account for 44–72% of the

#### Lactation Strategies and Milk Composition in Pinnipeds DOI: http://dx.doi.org/10.5772/intechopen.85386

In comparison with the milk of pinniped species, the milk produced by walruses

Milk is secreted by the mammary glands, and it is a complex fluid that contains five main components, water, lipids, proteins, sugars, and minerals [87–89]. Several of these can be divided further into more specific components. The concentrations of all the components in milk may vary both between species and within species at different stages of lactation and under different nutritional and environmental condition. Extensive reviews of the comparative composition of milk across species can be found elsewhere [87, 90–92]. The milk of pinnipeds differs substantially from other mammals in (a) high-fat concentration in milk and (b) virtual absence of lactose. These differences are a consequence of their lactation strategies and physiology in which the rapid transfer of energy-rich milk and the conservation of

Pinnipeds are a group of mammals that produce the richest energy-dense milk, and fat is the major contributor to the energy content of milk. Milk fat concentration varies considerably between pinnipeds species and within species (see Tables 3 and 4). Overall phocids produce milk with a higher concentration of fat than otariids although some otariids produce milk with high-fat concentrations (Tables 3 and 4). In most species the milk fat concentration varies in response to suckling, and as the mammary gland is being emptied, pinnipeds are not an exception. As in other mammals, milk fat concentration is influenced by stage of lactation and by nutritional status [88]; however, it is not clear how the latter is mediated in pinnipeds. This and other factors that affect milk composition in pinnipeds and in particular milk fat concentration are discussed further (see subsection factors that

Milk proteins are either caseins or whey proteins, and the kind and number of protein varies significantly between mammal species [104]. Proteins that are most common in milk are caseins, blood serum albumin, immunoglobulins, and alphalactalbumin, and the beta-lactoglobulin family is only found in the milk of rumi-

Protein such as casein has a nutritional function and is a source of amino acids for the suckling offspring. There is some knowledge about milk proteins and their function in terrestrial mammal; therefore, little can be suggested for homologous proteins found in the milk of pinniped. A whey protein, such as alpha-lactalbumin,

[84, 105, 106]. The protein alpha-lactalbumin is crucial for biosynthesis of lactose in milk, and therefore, the absence of lactose in pinniped milk has been associated with the lack of this protein [86]. By comparison with bovine milk, casein micelles found in northern fur seals milk were significantly larger, but the reason for this has not been addressed [86]. Caseins have been reported to account for 44–72% of the

has not been found in otariid milk and is practically absent in phocid milk

contains the lowest lipid and protein concentration (Table 4). The low-energy content of milk may be explained by the very long duration of lactation, and hence, there is less pressure in terms of maternal energy reserve depletion and for rapid transfer of energy-rich milk to the pup. Walruses inhabit the same marine environment as pagophilic phocid seals and thus must face the same high thermoregulatory needs and predation pressure. Walruses have evolved an aquatic lactation strategy in which foraging at sea and nursing their pup are not spatially and temporally separated. As a consequence they are able to extend their lactation period, lower the

Lactation in Farm Animals - Biology, Physiological Basis, Nutritional Requirements…

maternal cost (nutrient depletion), and lower pup mortality.

3. Milk composition in pinnipeds and other mammals

influence the milk composition) in this chapter.

nants and some species of artiodactyls [104].

water are essential.

12

total protein in phocid milk [87, 107], whereas in otariids, such as northern fur seals and Galapagos fur seals, casein accounted for 52 and 75%, respectively [83, 86, 108].

Moreover, pinniped milk has slightly higher amino acid concentration than in the milk of terrestrial mammal. However, both pinniped mammal species have similar range values for the proportion of total essential amino acids, total branched-chain amino acids, total sulfur amino acids, and most individual amino acids in relation to the total amino acids [83, 109]. Furthermore, the amino acid pattern and total amino acid concentration of milk were affected by stage of lactation in terrestrial mammals but not in pinnipeds [83, 109, 110]. This is contrary to Davis et al. [110] study that suggested that changes in amino acid pattern and total amino acid concentration during lactation were unrelated to phylogenetic order.

There are a great variety of saccharides in milk [111, 112]; however, lactose (disaccharide) is the dominant sugar, and it is synthesized in the mammary gland.

Notwithstanding, the milk of marine mammals contains only traces or no lactose at all. For instance, in human milk more than 100 oligosaccharides or saccharides that contain three or more monosaccharide residues have been observed. The chemical structures of around 80 have been reported [113]. In comparison with measurements of the concentrations of milk fat and protein, carbohydrates have been given little attention in pinnipeds, but data have been reported for Australian fur seals and hooded seal [114], harp seal [106], crabeater seal (Lobodon carcinophagus) [102, 115], and Arctic harbor seal (Phoca vitulina vitulina) [116]. It has been reported that phocid milk contains several oligossacharides of unknown structure, low concentrations of free lactose, and traces of glucose and galactose [102, 114, 115]. In the milk of most mammals apart from pinnipeds and cetaceans, lactose is the predominant component of carbohydrates [117]. As a consequence, pinnipeds have among the lowest milk carbohydrate concentration of any mammal. The chemical characterization of carbohydrates in hooded seal, crabeater seal and Australian fur seals, California sea lions, and northern fur seals has revealed that, unlike phocids, otariid milk does not contain free reducing saccharides or lactose [86, 102, 105, 106, 114, 118]. The biological function of milk oligosaccharides in phocids may be similar to that in terrestrial mammals, but this does not apply to otariids since they produce milk without free saccharides [114]. The concentration of carbohydrates in Antarctic fur seal milk decreases significantly throughout lactation [3], and similar data on the specific carbohydrates concentrations during the lactation period in otariids species is not available.

Lactose is a carbohydrate usually present in the milk of mammals but is lacking or virtually absent in pinniped milk. The protein α-lactalbumin is an essential component of the lactose synthetase complex, and it is not present in otariid. However, low activity of the protein α-lactalbumin in the milk of northern fur seals have been reported [119] which suggests an altered α-lactalbumin molecule with low biological activity rather than its complete absence in the milk of otariids [120]. The absence of lactose in otariids milk and the presence of traces of lactose in phocids milk are consequences for the need of water conservation [84] and consequently associated to the evolutionary history of pinniped. The need for water conservation is directly related to the secretion of lactose into milk. The later causes movement of water to maintain isotonicity with other body fluids [121] and consequently loss of water.

Furthermore, the virtual absence of lactose in milk could be associated to the inability of otariid to digest this carbohydrate. Most mammalian species are able to digest lactose through intestinal lactase activity, but some pinniped species' intestinal disaccharidases appear to be low [120, 122, 123]. For instance, lactose intolerance in California sea lions pups and adults has been demonstrated [124]; however,

intestinal lactase activity has been shown in crabeater seal pups [122]. Furthermore, it is also possible that the primary lack of sugar in the milk of pinniped resulted in the loss of the ability to digest lactose. The identification of specific carbohydrates in milk and the role of carbohydrate in milk secretion and as source of energy in

Minerals are important component in milk and are present in a variety of chemical forms (see Table 5). The major cations in milk are sodium (Na), potassium (K), calcium (Ca), and magnesium (Mg), while the major anions are phosphorus (P) as phosphate, chloride (Cl), and citrate [87, 121]. For instance, there are differences between the ratio Ca/P in pinniped milk (0.5–0.9:1) and terrestrial mammals (1.6:1), and the reason for the inverse Ca/P is unknown [121]

terrestrial mammals, and they play a crucial role in determining milk volume [121]. The amount of lactose secreted determines the volume of milk secreted, and this mechanism maintains the concentration of the ions relatively constant. These solutes act to maintain the isosmotic conditions (same osmotic pressure) between milk and blood by drawing water into the alveolar lumina [121]. Given that lactose is virtually absent in pinniped milk, it is unclear how pinniped controls the secretion

It is likely that in the absence of lactose, the control secretion of the aqueous

The mechanism controlling the secretion of water in pinnipeds is quite different from that in terrestrial mammals and that further investigation in this area is warranted.

Lactation strategies and milk composition are such important aspects of the reproduction in pinnipeds that they have been the subject of several investigations [5–7, 133–135]. The milk composition of the majority of the pinnipeds species has been described (see Tables 3 and 4). Great attention has been given to the factors (stage of lactation, attendance pattern, or maternal body condition) that affect the milk composition in phocid [61, 94, 97, 98]; however, in otariids it is unclear how these factors are influencing its composition. There are methodological issues in the data collection of milk samples that bias the results of the composition analysis and make our understanding of the lactation strategies in mammals difficult. Description of the milk composition of several mammalian species is available [90–92]; however, little attention was given in these earlier reviews to critically evaluate the information presented [117]. The data in the literature on milk composition of pinnipeds are often difficult to evaluate and must be interpreted with caution [99, 117, 136]. Unfortunately, most of these studies are biased due to a few number of samples collected, poor sampling regime, incorrect analytical procedures, and methodological difficulties which consequently make interspecific comparisons

As mentioned before, during lactation, otariid mothers fast during the attendance period on land and then replenish their energy reserves by foraging at sea. In order to fast during lactation, a period of high-energy demand, there must be significant metabolic adjustments such as reduction of glucose use to lower the catabolism of amino acids and tissue proteins for other vital body functions [5].

, and Cl are the main ions in the aqueous phase of milk of

, K<sup>+</sup>

, and Cl and the ratio

/K<sup>+</sup> is 1:3) [121].

pinniped warrant further investigation [3, 86, 114, 118, 121].

Lactation Strategies and Milk Composition in Pinnipeds DOI: http://dx.doi.org/10.5772/intechopen.85386

of the aqueous phase while maintaining water conservation.

/K<sup>+</sup> (1:1) in pinnipeds in comparison with mammals (Na<sup>+</sup>

4. Factors that influence the milk composition in pinnipeds

phase is associated with the higher concentration of Na<sup>+</sup>

4.1 Milk composition and maternal characteristics

(Table 5). Na+

of Na<sup>+</sup>

difficult [117].

15

, K<sup>+</sup>


Table 5.

Mineral constituents of milk of different species with emphasis on marine mammals.

Lactation Strategies and Milk Composition in Pinnipeds DOI: http://dx.doi.org/10.5772/intechopen.85386

Species Minerals in milk (mg/kg)

Lactation in Farm Animals - Biology, Physiological Basis, Nutritional Requirements…

1.3 0.8 1.7 0.2

990 1360

770 720

731 872

290 230

410 280

1060 1250

1500 1700

1200 700

800 500

Cow [87] 1250 960 580 1380 120 1030 Human [87] 330 150 150 550 40 430

Mineral constituents of milk of different species with emphasis on marine mammals.

630 1670

885 1003 1060 2030

567 1193 521 838 141 3.5 9.0 1191 3.7

1070 455

1250 468

310 210 80 130 20 110

530 570

Harp seal Phoca groenlandica [95]

Southern elephant seal Mirounga leonina [84]

Northern elephant seal M. angustirostris [61]

Northern fur seal Callorhinus ursinus [86]

Juan Fernandez fur seal A. Philippii [126]

Galapagos fur seal A. galapagoensis [21]

California sea lion Zalophus californianus [5]

Polar bear Ursus maritimus [127]

Black bear Ursus americanus [127]

Sea otter Enhydra lutris [128]

Spinner dolphin Stenella longirostris [129]

Pantropical spotted dolphin S. attenuata [129]

Pygmy sperm whale Kogia breviceps [131]

Blue whale Balaenoptera musculus [130]

Weddell seal Leptonychotes weddellii [5]

Donkey Equus asinus [132]

Common zebra E. burchelli [132]

Table 5.

14

Horse E. caballus [132] 800 500

Giant panda Ailuropoda melanoleuca [125] Ca P Na K Mg Fe Zn Cl Al Cu Ba Cr Mn Cd

950 708 699 456 104 53 3.6 3.6 1.8 1.8 0.6 0.6 0.1

intestinal lactase activity has been shown in crabeater seal pups [122]. Furthermore, it is also possible that the primary lack of sugar in the milk of pinniped resulted in the loss of the ability to digest lactose. The identification of specific carbohydrates in milk and the role of carbohydrate in milk secretion and as source of energy in pinniped warrant further investigation [3, 86, 114, 118, 121].

Minerals are important component in milk and are present in a variety of chemical forms (see Table 5). The major cations in milk are sodium (Na), potassium (K), calcium (Ca), and magnesium (Mg), while the major anions are phosphorus (P) as phosphate, chloride (Cl), and citrate [87, 121]. For instance, there are differences between the ratio Ca/P in pinniped milk (0.5–0.9:1) and terrestrial mammals (1.6:1), and the reason for the inverse Ca/P is unknown [121] (Table 5). Na+ , K<sup>+</sup> , and Cl are the main ions in the aqueous phase of milk of terrestrial mammals, and they play a crucial role in determining milk volume [121]. The amount of lactose secreted determines the volume of milk secreted, and this mechanism maintains the concentration of the ions relatively constant. These solutes act to maintain the isosmotic conditions (same osmotic pressure) between milk and blood by drawing water into the alveolar lumina [121]. Given that lactose is virtually absent in pinniped milk, it is unclear how pinniped controls the secretion of the aqueous phase while maintaining water conservation.

It is likely that in the absence of lactose, the control secretion of the aqueous phase is associated with the higher concentration of Na<sup>+</sup> , K<sup>+</sup> , and Cl and the ratio of Na<sup>+</sup> /K<sup>+</sup> (1:1) in pinnipeds in comparison with mammals (Na<sup>+</sup> /K<sup>+</sup> is 1:3) [121].

The mechanism controlling the secretion of water in pinnipeds is quite different from that in terrestrial mammals and that further investigation in this area is warranted.

#### 4. Factors that influence the milk composition in pinnipeds

Lactation strategies and milk composition are such important aspects of the reproduction in pinnipeds that they have been the subject of several investigations [5–7, 133–135]. The milk composition of the majority of the pinnipeds species has been described (see Tables 3 and 4). Great attention has been given to the factors (stage of lactation, attendance pattern, or maternal body condition) that affect the milk composition in phocid [61, 94, 97, 98]; however, in otariids it is unclear how these factors are influencing its composition. There are methodological issues in the data collection of milk samples that bias the results of the composition analysis and make our understanding of the lactation strategies in mammals difficult. Description of the milk composition of several mammalian species is available [90–92]; however, little attention was given in these earlier reviews to critically evaluate the information presented [117]. The data in the literature on milk composition of pinnipeds are often difficult to evaluate and must be interpreted with caution [99, 117, 136]. Unfortunately, most of these studies are biased due to a few number of samples collected, poor sampling regime, incorrect analytical procedures, and methodological difficulties which consequently make interspecific comparisons difficult [117].

#### 4.1 Milk composition and maternal characteristics

As mentioned before, during lactation, otariid mothers fast during the attendance period on land and then replenish their energy reserves by foraging at sea. In order to fast during lactation, a period of high-energy demand, there must be significant metabolic adjustments such as reduction of glucose use to lower the catabolism of amino acids and tissue proteins for other vital body functions [5].

The milk produced by otariids is low in carbohydrates concentration; therefore lipid and protein make the primary and secondary source of energy in milk (Table 4). Without doubt, good maternal body condition at the start of lactation will promote pup growth, and sufficient food intake to replenish energy reserves throughout lactation will enhance reproductive success of the mother [137]. Availability of food and maternal foraging success may be playing an important role in transferring energy to the pup while fasting and even regaining energy while foraging [138]. Consequently it is important to understand the relative contributions of maternal body mass, body condition, age, and foraging success to changes in milk composition and yield in lactating otariids.

has been shown to be correlated with maternal body mass in New Zealand sea lions [82] and Australian and Antarctic fur seals [3, 30], whereas no relationship was found in Australian sea lions [2, 28]. However, body mass is to some degree determined by body length and may not reflect the quantity of body reserves [141], and therefore, body mass may not be a good predictor of the quality of milk. To support this argument, terrestrial mammals such as dog [155] and dairy cows do vary in size within their species but their milk composition does not [156, 157]. Therefore, the variability in milk fat concentration in pinnipeds may have physiological basis

In mammals such as humans and dairy animals (cow and goat), body condition

While the mother is on land fasting and nursing the pup, the milk is initially synthesized from the nutrients that are obtained from the most recent digested food but as nutrient from the intestine is reduced, the nutrients from maternal body stores are mobilized [158]. If this is the case, then females with better body condition (measured from the relationship between body mass and body length) would secrete milk with higher concentration of fat than females with lower body condition. This has been shown in subantarctic fur seals and New Zealand sea lions

Female age could be associated with better foraging and reproductive success as

older females may have more experience in finding food in years of poor food availability. In addition, full-grown mature females do not need to divert nutrient toward their own growth and thus can divert more nutrient to provide for their pup. Older Antarctic fur seal and northern fur seal females had better reproductive performance than younger females, and this was suggested by greater natality rates, heavier natal pups weights, giving birth earlier in the season, and better possibilities of giving birth the following season [162, 163]. Moreover, in New Zealand sea lion maternal age had a positive effect on the quality of milk, and this could also be attributed to better body condition of older females with more maternal foraging experience than younger females [82]. In Antarctic fur seals, there was no apparent effect of maternal age on the time budget for foraging attendance [164]; however, in years of poor food resources, the foraging time budget was adjusted [24] which increased the cost of foraging in that year by 30–50% [165]. This is consistent with the hypothesis that mothers adjust their behavior to maximize energy delivery to

Body length has been used as an indirect measurement of age [142, 146, 163, 166, 167]. Maternal age estimated from body length did not increase the concentration of fat in the milk of subantarctic fur seals [10]; however, it did in Australian sea lions [28] and Australian fur seals [30]. Estimating age from body length suffers from bias and is not reliable to assign a pinniped to a particular age [146, 166–169], because the body grows at a progressively decelerating rate with age and the changes within age class and the overlap between age classes are

Notwithstanding, maternal age may affect and determine their body condition. For instance, young primiparous lactating otariids must be able to store energy reserves and replenish energy at a sufficient rate, in order to withstand the cost of

[10, 82] but remains to be studied in other otariid species.

(e.g., cow body condition is scored) determined concentration of fat in milk [159–161]. Similarly, lactating subantarctic fur seals (body mass/body length) and lactating New Zealand sea lions (body condition index) in good body condition produced milk with a greater concentration of lipid [10, 82]. Furthermore, the relationship between BCI and lipid and energy content of milk has been reported for in Australian fur seals and subantarctic fur seals [10, 30]. It appears that individual foraging success may influence body condition and eventually the milk

rather than influenced by body size [158].

Lactation Strategies and Milk Composition in Pinnipeds DOI: http://dx.doi.org/10.5772/intechopen.85386

quality in these species.

the pup.

substantial.

17

Body condition indexes have been widely used in pinnipeds for many reasons: as indicators of nutritional state, to measure the response to environmental perturbations, during molting stage, to relate to reproductive success and growth [20, 48, 82, 139–143]. Two methods of estimating body condition have been used in pinnipeds; one method divides the body mass by body length [139], while the second method estimates the individual residual value of the linear regression between the body mass and body length [141]. Although these methods of body index calculation have not been standardized, making interspecies comparisons difficult, the second method has shown to be a better predictor of the body condition in otariids [82, 144–148].

In South American fur seals in the Pacific Ocean, drastic environmental perturbations such as ENSO changed the attendance and foraging patterns in the lactating females and their foraging success [149]. The low availability of food sources during ENSO resulted in longer maternal foraging trips which may have affected milk quality and volume. Not being able to replenish their body reserves may have decreased their body weight and thus body condition and reduced the benefit to foraging cost ratio [149]. Furthermore, failure in reproductive performance has been also reported in pinnipeds due to changes in body condition. Body condition in Cape fur seal (Arctocephalus pusillus pusillus) females influenced their ability to become pregnant or maintain pregnancy [141]. Furthermore, females with poor body condition were less likely to be pregnant than females with better body condition during pregnancy. Also, poor body condition in pregnant Steller's sea lion due to nutritional stress caused lower pup production in the subsequent season [143]. This indicates that food resources were not sufficient to support the energy demands of the reproductive strategy in this species. Similarly, when food resources were scarce for Cape fur seals resulting in low body condition, pregnancy was likely to fail through abortion [141]. In Antarctic waters, variation in food availability in any year has also been associated with low pup production in the following year for Antarctic fur seals around South Georgia [150].

On the other hand, in years when food sources are plentiful, pup production increased and also pup growth, and mothers were able to replenish and store energy body reserves to improve their body conditions for the following breeding season [4, 27]. An increased number of pups were most likely the result of an increase in the number of females in which embryos were implanted and which carried a fetus to term [150]. Lactating otariid females with low foraging success may spend more time at sea and therefore increase the chances of pup mortality due to malnutrition, hypothermia, trauma, or infection and therefore reduce their reproductive success [151, 152].

Given that in other species variation in milk composition indicates the effects of environmental and physiological factors [99, 153, 154], the relationships between these factors and their influence on milk composition in pinnipeds should be investigated. Body mass and body condition are directly linked to individual foraging success and can be used as proxy for the availability of local food resources. Milk fat

#### Lactation Strategies and Milk Composition in Pinnipeds DOI: http://dx.doi.org/10.5772/intechopen.85386

The milk produced by otariids is low in carbohydrates concentration; therefore lipid and protein make the primary and secondary source of energy in milk (Table 4). Without doubt, good maternal body condition at the start of lactation will promote pup growth, and sufficient food intake to replenish energy reserves throughout lactation will enhance reproductive success of the mother [137]. Availability of food and maternal foraging success may be playing an important role in transferring energy to the pup while fasting and even regaining energy while foraging [138]. Consequently it is important to understand the relative contributions of maternal body mass, body condition, age, and foraging success to changes in milk composi-

Lactation in Farm Animals - Biology, Physiological Basis, Nutritional Requirements…

Body condition indexes have been widely used in pinnipeds for many reasons: as indicators of nutritional state, to measure the response to environmental perturbations, during molting stage, to relate to reproductive success and growth [20, 48, 82, 139–143]. Two methods of estimating body condition have been used in pinnipeds; one method divides the body mass by body length [139], while the second method estimates the individual residual value of the linear regression between the body mass and body length [141]. Although these methods of body index calculation have not been standardized, making interspecies comparisons difficult, the second method has shown to be a better predictor of the body condition in otariids

In South American fur seals in the Pacific Ocean, drastic environmental perturbations such as ENSO changed the attendance and foraging patterns in the lactating females and their foraging success [149]. The low availability of food sources during ENSO resulted in longer maternal foraging trips which may have affected milk quality and volume. Not being able to replenish their body reserves may have decreased their body weight and thus body condition and reduced the benefit to foraging cost ratio [149]. Furthermore, failure in reproductive performance has been also reported in pinnipeds due to changes in body condition. Body condition in Cape fur seal (Arctocephalus pusillus pusillus) females influenced their ability to become pregnant or maintain pregnancy [141]. Furthermore, females with poor body condition were less likely to be pregnant than females with better body condition during pregnancy. Also, poor body condition in pregnant Steller's sea lion due to nutritional stress caused lower pup production in the subsequent season [143]. This indicates that food resources were not sufficient to support the energy demands of the reproductive strategy in this species. Similarly, when food resources were scarce for Cape fur seals resulting in low body condition, pregnancy was likely to fail through abortion [141]. In Antarctic waters, variation in food availability in any year has also been associated with low pup production in the following year for

On the other hand, in years when food sources are plentiful, pup production increased and also pup growth, and mothers were able to replenish and store energy body reserves to improve their body conditions for the following breeding season [4, 27]. An increased number of pups were most likely the result of an increase in the number of females in which embryos were implanted and which carried a fetus to term [150]. Lactating otariid females with low foraging success may spend more time at sea and therefore increase the chances of pup mortality due to malnutrition, hypothermia, trauma, or infection and therefore reduce their reproductive success

Given that in other species variation in milk composition indicates the effects of environmental and physiological factors [99, 153, 154], the relationships between these factors and their influence on milk composition in pinnipeds should be investigated. Body mass and body condition are directly linked to individual foraging success and can be used as proxy for the availability of local food resources. Milk fat

tion and yield in lactating otariids.

Antarctic fur seals around South Georgia [150].

[82, 144–148].

[151, 152].

16

has been shown to be correlated with maternal body mass in New Zealand sea lions [82] and Australian and Antarctic fur seals [3, 30], whereas no relationship was found in Australian sea lions [2, 28]. However, body mass is to some degree determined by body length and may not reflect the quantity of body reserves [141], and therefore, body mass may not be a good predictor of the quality of milk. To support this argument, terrestrial mammals such as dog [155] and dairy cows do vary in size within their species but their milk composition does not [156, 157]. Therefore, the variability in milk fat concentration in pinnipeds may have physiological basis rather than influenced by body size [158].

In mammals such as humans and dairy animals (cow and goat), body condition (e.g., cow body condition is scored) determined concentration of fat in milk [159–161]. Similarly, lactating subantarctic fur seals (body mass/body length) and lactating New Zealand sea lions (body condition index) in good body condition produced milk with a greater concentration of lipid [10, 82]. Furthermore, the relationship between BCI and lipid and energy content of milk has been reported for in Australian fur seals and subantarctic fur seals [10, 30]. It appears that individual foraging success may influence body condition and eventually the milk quality in these species.

While the mother is on land fasting and nursing the pup, the milk is initially synthesized from the nutrients that are obtained from the most recent digested food but as nutrient from the intestine is reduced, the nutrients from maternal body stores are mobilized [158]. If this is the case, then females with better body condition (measured from the relationship between body mass and body length) would secrete milk with higher concentration of fat than females with lower body condition. This has been shown in subantarctic fur seals and New Zealand sea lions [10, 82] but remains to be studied in other otariid species.

Female age could be associated with better foraging and reproductive success as older females may have more experience in finding food in years of poor food availability. In addition, full-grown mature females do not need to divert nutrient toward their own growth and thus can divert more nutrient to provide for their pup. Older Antarctic fur seal and northern fur seal females had better reproductive performance than younger females, and this was suggested by greater natality rates, heavier natal pups weights, giving birth earlier in the season, and better possibilities of giving birth the following season [162, 163]. Moreover, in New Zealand sea lion maternal age had a positive effect on the quality of milk, and this could also be attributed to better body condition of older females with more maternal foraging experience than younger females [82]. In Antarctic fur seals, there was no apparent effect of maternal age on the time budget for foraging attendance [164]; however, in years of poor food resources, the foraging time budget was adjusted [24] which increased the cost of foraging in that year by 30–50% [165]. This is consistent with the hypothesis that mothers adjust their behavior to maximize energy delivery to the pup.

Body length has been used as an indirect measurement of age [142, 146, 163, 166, 167]. Maternal age estimated from body length did not increase the concentration of fat in the milk of subantarctic fur seals [10]; however, it did in Australian sea lions [28] and Australian fur seals [30]. Estimating age from body length suffers from bias and is not reliable to assign a pinniped to a particular age [146, 166–169], because the body grows at a progressively decelerating rate with age and the changes within age class and the overlap between age classes are substantial.

Notwithstanding, maternal age may affect and determine their body condition. For instance, young primiparous lactating otariids must be able to store energy reserves and replenish energy at a sufficient rate, in order to withstand the cost of

lactation and her metabolic needs and growth. The mechanisms in which maternal body condition affect the composition of milk in otariids are still unclear. Interannual variability in food sources has direct impact on maternal foraging success and consequently on body condition and thus the female's reproductive success and lactation performance. Some studies have investigated the effect of maternal age on milk composition. Maternal age may influence indirectly the milk composition via body condition, and this hypothesis may be tested in a species for which there are age data.

#### 4.2 Milk composition and attendance pattern

The differences in milk composition among otariid species could be explained by the duration of the foraging trip, i.e., females of a species that make long foraging trip may secrete milk with higher-lipid concentration than a species making shorter foraging trips [21, 31]. In other words, the energy content of milk increases with the length of the foraging trip [135]. This in agreement with the central place foraging theory that postulates that parents that have to make long foraging trip, away from the central place (nest or breeding site), to their feeding grounds should make fewer foraging trips and gain more energy per trip. On the other hand, parents that forage near the central place would make many short foraging trips and return with lower energy per trip [170]. This theory has been tested in birds and otariids [171, 172].

The high concentration of nutrients in the milk is sufficient to sustain the pup while fasting on land during its mother's absence at sea [13, 31]. This is true for species that have among the longest foraging trips reported for any otariids such as the subantarctic fur seals, the Juan Fernandez fur seals, and the Guadalupe fur seals (Figure 4 and Table 6). For females producing milk with high concentration of lipids when making long foraging trips, there must be physiological and reproductive advantages [27, 29, 35]. These advantages may include less pressure on water balance due to reduced need for water, and the capacity of the mammary gland is not a limiting factor when secreting milk with high solid content. Furthermore, the mechanisms regulating the milk secretion in which the mammary gland is able to resume lactation after long foraging trips (more than 12 days) and in the absence of the stimulus of the suckling pup and milk removal are unknown. The mechanism of milk secretion in terrestrial mammals, such as dairy animals, is controlled by autocrine factors and cell stretching [173, 174], but these are yet to be investigated in pinnipeds.

capacity of Antarctic fur seals was measured by complete manual evacuation and indicated that mammary glands were not completely full when the mother arrived ashore [31]. It is likely that the capacity of the mammary gland to store milk is not limiting the duration of foraging trips; however, it is possible that it is limited by a

The relationship between foraging trip duration (mean absence duration in days) and milk lipid concentration

in 13 species of otariids (data from sources in Tables 4 and 6). SL = sea lions, FS = fur seals.

Lactation Strategies and Milk Composition in Pinnipeds DOI: http://dx.doi.org/10.5772/intechopen.85386

The relationship between foraging trip duration and milk lipid concentration has been demonstrated between and within otariid species. The second of the two has been demonstrated in a few species. A significant relationship between milk lipid concentration and the duration of the preceding foraging trip in Australian and Antarctic fur seals was found [30, 31]. By contrast trip duration and milk fat content were not related in studies carried out on Australian [28] and New Zealand sea lions [82] and subantarctic fur seals [10]. The poor relationship found in subantarctic fur seals was thought to be a consequence of individual maternal foraging skills, and thus, the quality of the milk would have been determined by this

Australian and New Zealand sea lions conform with the hypothesis that species

that make short foraging trips secrete relatively low milk fat concentration [21, 82, 171]. Australian sea lions, as an adaptive response to inhabiting a lowenergy marine environment, have prolonged the lactation period in which mothers have lowered the energy intake of their pup by secreting a low-energy milk [22]. Galapagos fur seals also produce a low-energy milk and have a foraging trip lasting 1.3 days and a prolonged lactation period (Tables 1 and 6). The duration of the foraging trips of lactating Galapagos fur seals appears to be regulated by short-term fluctuations of food availability [22]. Both temperate and tropical species, Australian sea lions and Galapagos fur seals, respectively, have adopted a different strategy to polar species in that they are obligated to extend their lactation period. As otariid

set point of the nutritional satiation reached by the mother [13].

factor [10].

19

Figure 4.

Otariid species that make long maternal foraging trips at sea may have limited capacity in their mammary gland in order to store great amount of milk.

An explanation is that the mammary glands might have a large storage capacity twosome with a slow secretion rate of high energy-rich milk while foraging at sea [5]. This argument is supported by the weak negative relationship between the foraging trip duration of lactating Antarctic fur seals and the milk secretion rate while at sea and by the positive correlation between milk secretion rate and the duration of pup attendance on land [3]. In addition due to the absence of the suckling stimulus and milk removal, which are crucial for the maintenance of mammary gland function in other species, the mammary gland may be at risk of involution [5, 29]. How otariids are able to contain the involution of the mammary gland in the absence of the suckling stimulus and milk removal is still not clear.

Mammary gland size in pinnipeds is estimated based on the mammary gland weight relative to body weight, indicating that most otariids have large mammary glands in comparison with terrestrial mammals [5, 29]. The mammary gland

Lactation Strategies and Milk Composition in Pinnipeds DOI: http://dx.doi.org/10.5772/intechopen.85386

Figure 4.

lactation and her metabolic needs and growth. The mechanisms in which maternal

The differences in milk composition among otariid species could be explained by the duration of the foraging trip, i.e., females of a species that make long foraging trip may secrete milk with higher-lipid concentration than a species making shorter foraging trips [21, 31]. In other words, the energy content of milk increases with the length of the foraging trip [135]. This in agreement with the central place foraging theory that postulates that parents that have to make long foraging trip, away from the central place (nest or breeding site), to their feeding grounds should make fewer foraging trips and gain more energy per trip. On the other hand, parents that forage near the central place would make many short foraging trips and return with lower energy per trip [170]. This theory has been tested in birds and otariids [171, 172]. The high concentration of nutrients in the milk is sufficient to sustain the pup while fasting on land during its mother's absence at sea [13, 31]. This is true for species that have among the longest foraging trips reported for any otariids such as the subantarctic fur seals, the Juan Fernandez fur seals, and the Guadalupe fur seals (Figure 4 and Table 6). For females producing milk with high concentration of lipids when making long foraging trips, there must be physiological and reproductive advantages [27, 29, 35]. These advantages may include less pressure on water balance due to reduced need for water, and the capacity of the mammary gland is not a limiting factor when secreting milk with high solid content. Furthermore, the mechanisms regulating the milk secretion in which the mammary gland is able to resume lactation after long foraging trips (more than 12 days) and in the absence of the stimulus of the suckling pup and milk removal are unknown. The mechanism of milk secretion in terrestrial mammals, such as dairy animals, is controlled by autocrine factors and cell stretching [173, 174], but these are yet to be investigated in

Otariid species that make long maternal foraging trips at sea may have limited

An explanation is that the mammary glands might have a large storage capacity twosome with a slow secretion rate of high energy-rich milk while foraging at sea [5]. This argument is supported by the weak negative relationship between the foraging trip duration of lactating Antarctic fur seals and the milk secretion rate while at sea and by the positive correlation between milk secretion rate and the duration of pup attendance on land [3]. In addition due to the absence of the suckling stimulus and milk removal, which are crucial for the maintenance of mammary gland function in other species, the mammary gland may be at risk of involution [5, 29]. How otariids are able to contain the involution of the mammary gland in the absence of the suckling stimulus and milk removal is still

Mammary gland size in pinnipeds is estimated based on the mammary gland weight relative to body weight, indicating that most otariids have large mammary glands in comparison with terrestrial mammals [5, 29]. The mammary gland

capacity in their mammary gland in order to store great amount of milk.

body condition affect the composition of milk in otariids are still unclear. Interannual variability in food sources has direct impact on maternal foraging success and consequently on body condition and thus the female's reproductive success and lactation performance. Some studies have investigated the effect of maternal age on milk composition. Maternal age may influence indirectly the milk composition via body condition, and this hypothesis may be tested in a species for

Lactation in Farm Animals - Biology, Physiological Basis, Nutritional Requirements…

which there are age data.

pinnipeds.

not clear.

18

4.2 Milk composition and attendance pattern

The relationship between foraging trip duration (mean absence duration in days) and milk lipid concentration in 13 species of otariids (data from sources in Tables 4 and 6). SL = sea lions, FS = fur seals.

capacity of Antarctic fur seals was measured by complete manual evacuation and indicated that mammary glands were not completely full when the mother arrived ashore [31]. It is likely that the capacity of the mammary gland to store milk is not limiting the duration of foraging trips; however, it is possible that it is limited by a set point of the nutritional satiation reached by the mother [13].

The relationship between foraging trip duration and milk lipid concentration has been demonstrated between and within otariid species. The second of the two has been demonstrated in a few species. A significant relationship between milk lipid concentration and the duration of the preceding foraging trip in Australian and Antarctic fur seals was found [30, 31]. By contrast trip duration and milk fat content were not related in studies carried out on Australian [28] and New Zealand sea lions [82] and subantarctic fur seals [10]. The poor relationship found in subantarctic fur seals was thought to be a consequence of individual maternal foraging skills, and thus, the quality of the milk would have been determined by this factor [10].

Australian and New Zealand sea lions conform with the hypothesis that species that make short foraging trips secrete relatively low milk fat concentration [21, 82, 171]. Australian sea lions, as an adaptive response to inhabiting a lowenergy marine environment, have prolonged the lactation period in which mothers have lowered the energy intake of their pup by secreting a low-energy milk [22]. Galapagos fur seals also produce a low-energy milk and have a foraging trip lasting 1.3 days and a prolonged lactation period (Tables 1 and 6). The duration of the foraging trips of lactating Galapagos fur seals appears to be regulated by short-term fluctuations of food availability [22]. Both temperate and tropical species, Australian sea lions and Galapagos fur seals, respectively, have adopted a different strategy to polar species in that they are obligated to extend their lactation period. As otariid


#### Lactation in Farm Animals - Biology, Physiological Basis, Nutritional Requirements…

duration ashore, and primary productivity, indicating that food source location and

At least for some otariid species, long foraging trips are preceded by long nursing bouts ashore. At some point, when nursing the pup ashore, the energy needed to produce milk must come from body reserves; in this scenario the rate of milk secretion and rate of energy delivered to the pup would be dependent on the maternal body lipid storage capacity. In fact, 42–79% of the milk energy transferred to Antarctic fur seals' pup comes from maternal body reserves [31]. At least for this species, the longer the duration of the foraging trip, the greater the proportion of milk energy delivered to the pup is derived from body stores [31]. Probably the most beneficial cost-efficient lactating strategy would be to maximize energy transfer to the pups, by producing and storing an energy-lipid-rich milk while foraging at sea, and store excess nutrients as body lipids and protein to be used to secrete milk while nursing the pup ashore [31]. While ashore, the rate of nutrient transfer to the pup is maximized by increasing the milk production and the concentration of milk solids. Within otariid species two distinctive strategies of energy transfer to the pup can be identified, one that makes long foraging trips and maximized their energy transfer to the pup by secreting nutrient-rich milk and those species that makes shorter foraging trips and produce a low nutrient-rich milk

There is a strong relationship between milk composition and attendance pattern in otariids in particular for species making long foraging trip at sea; however, for otariid species making short foraging trips, this relationship is unclear. Location of breeding site (latitude), distance between breeding site and foraging ground, and availability of food source may influence the attendance pattern of lactating females. The fact that lactating otariids are absent for the longest inter-suckling period of any of the mammals makes otariids an interesting group of mammals for

The general effect of stage of lactation on milk composition seems to be consistent across species [117, 184–188]; however, there are differences between species

The fat content of the milk of phocids increases as lactation progresses, and pup growth rate reflects the extent of this increase (Table 3) [189]. Phocid offspring are not different from other mammalian species, and the demands for energy by the pup increase as lactation progresses [189], but how the increase in energy demand could influence the increase in milk lipid concentration has not yet been explained. Some phocid species secrete low-fat milk in early lactation, but protein concentration remains unchanged throughout lactation (Table 3). The low protein content in phocid milk is a consequence relatively small to the proportion of the gain in the young's lean body mass (Table 3). To give an example, hooded seals and bearded seals produce the lowest protein concentration of any mammalian milk [7, 97], and in hooded seal pups, the low protein content was associated with a low gain in lean

In phocids the concentration of water in milk decreases, and lipid concentration

increases as lactation progresses [51, 61, 94, 96, 99–101]. Similarly, in harp seal milk, the protein content remained constant, and milk fat content increased

in the degree of change in the milk composition as lactation progresses.

availability were determining the foraging pattern [35].

Lactation Strategies and Milk Composition in Pinnipeds DOI: http://dx.doi.org/10.5772/intechopen.85386

testing the central place foraging theory [170].

4.3 Milk composition and stage of lactation

(Figure 4).

4.3.1 Seals (phocids)

body mass [74].

21

#### Table 6.

Temporal parameters of attendance pattern in otariids.

females depend upon their dietary intake to sustain lactation [135], and by regulation the duration of their foraging trips to food availability they are able to withstand a long lactation period. This strategy does not necessary occur at high latitudes in which the marine environment has dramatic rise in primary productivity during the short summer season and otariids are able forage successfully and complete lactation in a short period of time.

Subantarctic and Juan Fernandez fur seals inhabit lower latitudes, but contrary to other low-latitude otariids species, they conduct very long foraging trips (mean of 15.9 and 12.3 days, respectively) (Figure 4, Table 6). As would be expected for long forager trip species, they secrete milk with high lipid contents (38.6 and 41.4%, respectively). Moreover, these two species have one of the longest inter-suckling intervals and highest milk lipid concentration during the first month of early lactation among otariids [10, 29]. Both species leave their local low productive waters and travel long distances to waters of higher productivity [10, 35]. The similarity of the attendance patterns of Antarctic and subantarctic fur seals breeding at Macquarie island indicated that prey availability might be playing a major role influencing pattern of foraging and attendance cycles [9]. This was also shown to be true for Juan Fernandez fur seals that had a correlation between foraging trip, visit

#### Lactation Strategies and Milk Composition in Pinnipeds DOI: http://dx.doi.org/10.5772/intechopen.85386

duration ashore, and primary productivity, indicating that food source location and availability were determining the foraging pattern [35].

At least for some otariid species, long foraging trips are preceded by long nursing bouts ashore. At some point, when nursing the pup ashore, the energy needed to produce milk must come from body reserves; in this scenario the rate of milk secretion and rate of energy delivered to the pup would be dependent on the maternal body lipid storage capacity. In fact, 42–79% of the milk energy transferred to Antarctic fur seals' pup comes from maternal body reserves [31]. At least for this species, the longer the duration of the foraging trip, the greater the proportion of milk energy delivered to the pup is derived from body stores [31]. Probably the most beneficial cost-efficient lactating strategy would be to maximize energy transfer to the pups, by producing and storing an energy-lipid-rich milk while foraging at sea, and store excess nutrients as body lipids and protein to be used to secrete milk while nursing the pup ashore [31]. While ashore, the rate of nutrient transfer to the pup is maximized by increasing the milk production and the concentration of milk solids. Within otariid species two distinctive strategies of energy transfer to the pup can be identified, one that makes long foraging trips and maximized their energy transfer to the pup by secreting nutrient-rich milk and those species that makes shorter foraging trips and produce a low nutrient-rich milk (Figure 4).

There is a strong relationship between milk composition and attendance pattern in otariids in particular for species making long foraging trip at sea; however, for otariid species making short foraging trips, this relationship is unclear. Location of breeding site (latitude), distance between breeding site and foraging ground, and availability of food source may influence the attendance pattern of lactating females. The fact that lactating otariids are absent for the longest inter-suckling period of any of the mammals makes otariids an interesting group of mammals for testing the central place foraging theory [170].

#### 4.3 Milk composition and stage of lactation

The general effect of stage of lactation on milk composition seems to be consistent across species [117, 184–188]; however, there are differences between species in the degree of change in the milk composition as lactation progresses.

#### 4.3.1 Seals (phocids)

females depend upon their dietary intake to sustain lactation [135], and by regulation the duration of their foraging trips to food availability they are able to withstand a long lactation period. This strategy does not necessary occur at high

latitudes in which the marine environment has dramatic rise in primary productivity during the short summer season and otariids are able forage successfully and

Subantarctic and Juan Fernandez fur seals inhabit lower latitudes, but contrary to other low-latitude otariids species, they conduct very long foraging trips (mean of 15.9 and 12.3 days, respectively) (Figure 4, Table 6). As would be expected for long forager trip species, they secrete milk with high lipid contents (38.6 and 41.4%, respectively). Moreover, these two species have one of the longest inter-suckling intervals and highest milk lipid concentration during the first month of early lactation among otariids [10, 29]. Both species leave their local low productive waters and travel long distances to waters of higher productivity [10, 35]. The similarity of the attendance patterns of Antarctic and subantarctic fur seals breeding at Macquarie island indicated that prey availability might be playing a major role influencing pattern of foraging and attendance cycles [9]. This was also shown to be true for Juan Fernandez fur seals that had a correlation between foraging trip, visit

complete lactation in a short period of time.

\*Attendance pattern were recorder at early lactation.

Temporal parameters of attendance pattern in otariids.

Species Time to first

South American fur seal [175]

Subantarctic fur seal [27]

California sea lion [19, 177]

Antarctic fur seal [20, 23, 31]

New Zealand sea lion\*

New Zealand fur seal

Australian seal lion [1, 28, 183]

Juan Fernandez fur

[180–182]

[40, 41]

seal [35]

Table 6.

20

departure (days)

Australian fur seal [30] — 5.0 0.1 — —

Lactation in Farm Animals - Biology, Physiological Basis, Nutritional Requirements…

Guadalupe fur seal [176] — 11.5 0.1 5.0 0.1 70

Cape fur seal [43] 4.3 3.3 3.0 2.5 2.4 1.4 56

Steller sea lion [37, 178] 5.8 0.6 1.5 0.1 0.86 0.05 64 Galapagos sea lion [175] 6.8 2.1 0.5 0.1 0.6 0.1 47

Galapagos fur seal [175] 7.4 1.2 1.3 0.1 1.0 0.1 57 Northern fur seal [179] 7.4 0.1 5.9 0.1 2.2 0.1 73

Time absent (days)

— 4.6 0.1 1.3 0.1 78

— 15.9 4.6 3.8 1.1 81

5–8 4.3 0.5 1.4 0.1 75

6.9 0.1 4.2 0.8 1.8 0.5 67

8.6 0.2 1.7–2.7 1.2 0.1 57–69

9.7 0.1 4.2 0.1 1.8 0.1 70

9.8 1.8 2.0 0.5 1.4 0.3 59

11.3 3.4 12.3 0.1 5.3 0.1 70

Time presence (days)

Time absent (%)

> The fat content of the milk of phocids increases as lactation progresses, and pup growth rate reflects the extent of this increase (Table 3) [189]. Phocid offspring are not different from other mammalian species, and the demands for energy by the pup increase as lactation progresses [189], but how the increase in energy demand could influence the increase in milk lipid concentration has not yet been explained. Some phocid species secrete low-fat milk in early lactation, but protein concentration remains unchanged throughout lactation (Table 3). The low protein content in phocid milk is a consequence relatively small to the proportion of the gain in the young's lean body mass (Table 3). To give an example, hooded seals and bearded seals produce the lowest protein concentration of any mammalian milk [7, 97], and in hooded seal pups, the low protein content was associated with a low gain in lean body mass [74].

> In phocids the concentration of water in milk decreases, and lipid concentration increases as lactation progresses [51, 61, 94, 96, 99–101]. Similarly, in harp seal milk, the protein content remained constant, and milk fat content increased

throughout lactation [94, 95, 106]. An explanation for the relatively high concentration of water in milk in early lactation is to provide the pup with water since the newborn cannot catabolize water from lipid reserves as an adequate body lipid layer (blubber) has not yet been formed. In consequence, milk provides free water to the pup when it is needed most, and the decline in water concentration in milk will coincide with the time the young is less dependent on free water [94].

composition [3, 28]. Kretzman et al. [28] and Gales et al. [2] found high variability in milk lipid concentration between and within individual Australian sea lions. However, they were unable to identify which factors contributed most to the variation in milk composition. In Antarctic fur seals, days postpartum and maternal mass contributed to the variation in milk lipid, and it was suggested that foraging trip duration also explained some of the variation [3]. These authors have recognized that extensive and systematic sampling is needed in order to describe milk composition in otariids and control for intraspecific variation in milk

Lactation Strategies and Milk Composition in Pinnipeds DOI: http://dx.doi.org/10.5772/intechopen.85386

The trend in changes in otariid milk composition during lactation is as follows: milk lipid and gross energy concentration increases during the first stages of lactation and peaks at mid-lactation and then decreases in the course of later stages of lactation (Table 4). Water content in milk changes inversely with milk lipid concentration, while milk protein concentration stays somewhat unchanged throughout the lactation period [10]. Although not all otariid species follow these trends, Galapagos fur seals, for example, produce milk that decreases in fat concentration with pup age in early lactation [21], and hence in the course of the perinatal period, they use their body fat storage to secrete lipid-rich milk. This has some advantages as the mother can conserve body water and the neonate is able to build up the layer of blubber that will act as insulation layer and energy reserve for the approaching period of fasting. The mother's water balance enhances at the start of the foraging trip, and on her return, she nurses the pup with a diluted milk that meliorate the pup's capacity to deal with the high temperatures at the Galapagos

Protein concentration in milk of Antarctic fur seals declined in 1 year but heightened in the following 2 years [3] but did not changed in Australian fur seals [30]. The increase of milk protein concentration during lactation may respond to the need to incorporate essential nutrient for pup growth. The proportions of the total protein in milk of whey and casein changed in the milk are produced by Galapagos fur seals at early and mid-lactation (40–25%, 60–75%, respectively) [83]. The reason and connotation for the changes in the proportions of whey and casein

of the total protein in milk of Galapagos fur seals remain to be elucidated.

related with increment in the duration of foraging trips and/or the stage of

possible that other mechanisms may be acting. After the long and energydemanding perinatal period, the mother must replenish energy reserves and enhance body condition, in order to produce a higher-lipid concentrated milk at early lactation [18, 140]. Maternal body condition had a significant effect on milk lipid in subantarctic fur seals [10] and New Zealand sea lions [82], but it is not known whether this applies to other otariid species. The increasing demands of the growing pup may affect the maternal response and increase milk fat

Increment in fat and energy concentration of milk at early lactation has been

lactation in some species of otariids [2, 3, 9, 30, 191]. However, in some species the foraging trip duration was not related to changes in milk composition; hence, it is

By the last month of the lactation period, milk lipid content tends to decrease as shown in Australian sea lions and Australian fur seals and subantarctic fur seals [2, 10, 30]. In subantarctic fur seals, the data suggested that the relationship between milk lipid concentration and at the end of the lactation stage was best described by an asymptotic relationship, i.e., decrease in lipid content. The decrease in milk lipid concentration, i.e., lower rate of energy transfer to the pup, at the end of lactation could be associated with the proximity to the pup's weaning process and higher-energy demands of gestation [10, 30]. This argument was supported by a

composition [3, 28].

Islands [21].

concentration [10].

23

Despite the short lactation duration in phocid, the pup is weaned with large weaning mass, and this is possible because the pup is nursed with very energy-rich milk and lipids are deposited rapidly in the blubber. Furthermore, in comparison with terrestrial non-fasting mammals, phocids have greater milk energy output rates [117]. Phocids are able to do so, due to the large maternal body mass that can store large quantities of energy in the form of lipids (blubber) which allow them to withstand the high cost of lactation by mobilization stored energy reserves [72]. However, some small body size phocid species such as harp seals, Weddell seals, bearded seals, and harbor seals feed at some stage during the lactation period [72, 74]. Harbor seals are known to feed from mid-lactation onward [73], most likely because energy reserves are depleted, and hence, they are unable to sustain lactation while fasting [72]. It appears that maternal size in harbor seals constrains the proportion of body fat that can be stored [73]. Furthermore, lactating harbor seals depleted 33% of their body mass during the first 80% of the nursing period and depleted their body reserves faster than other phocids [72]. A limited amount of energy stored coupled with rapid energy depletion during lactation cannot be sustained without feeding [69]. It has been suggested that it is likely that half of the phocid species may feed during lactation [6]; however, whether this occurs only in the smaller phocid species is still to be investigated.

In conclusion, lactating phocid produces great amount of energy in the form of very rich lipid milk that is transferred to the pup in a short time, and this energy is deposited as body reserves to be mobilized during the postweaning period. In addition, the pup is able to rapidly assimilate the lipid-rich milk and deposit the lipid in the blubber which is crucial for insulation and for postweaning energy reserves. The needs of the neonate seem to parallel the milk composition, and most phocids appear to follow the same trends. Some evidence has shown that not all phocid species are fast for the entire lactation period. Small body size phocids are unable to endure the cost of lactation and maternal metabolism solely with her body energy reserves and must forage to regain energy. These species of phocid have adopted an "otariid-like foraging strategy."

#### 4.3.2 Sea lion and fur seals (otariids)

Data on changes in milk composition throughout the whole lactation period for 6 out of 16 otariid species have been investigated [2, 3, 5, 10, 30, 190]. The general trend in these species is that milk fat concentration increases progressively, whereas protein content remains fairly constant throughout the lactation period. Less complete, but otherwise useful, data are available from northern fur seals [191], New Zealand sea lions [82], Galapagos fur seals, and Galapagos sea lions [21].

Increase in foraging trip duration related to stage of lactation and/or change in food availability [1, 163, 164] may influence variation in milk composition during lactation. It is possible that there is a combination between the effect of stage of lactation and foraging trip duration on the composition of milk. Stage of lactation was responsible for most of the changes observed in milk composition of subantarctic fur seals [10]; however, in Antarctic fur seals and Australian sea lions, stage of lactation was responsible for only a small proportion of the changes in milk

throughout lactation [94, 95, 106]. An explanation for the relatively high concentration of water in milk in early lactation is to provide the pup with water since the newborn cannot catabolize water from lipid reserves as an adequate body lipid layer (blubber) has not yet been formed. In consequence, milk provides free water to the pup when it is needed most, and the decline in water concentration in milk will

Despite the short lactation duration in phocid, the pup is weaned with large weaning mass, and this is possible because the pup is nursed with very energy-rich milk and lipids are deposited rapidly in the blubber. Furthermore, in comparison with terrestrial non-fasting mammals, phocids have greater milk energy output rates [117]. Phocids are able to do so, due to the large maternal body mass that can store large quantities of energy in the form of lipids (blubber) which allow them to withstand the high cost of lactation by mobilization stored energy reserves [72]. However, some small body size phocid species such as harp seals, Weddell seals, bearded seals, and harbor seals feed at some stage during the lactation period [72, 74]. Harbor seals are known to feed from mid-lactation onward [73], most likely because energy reserves are depleted, and hence, they are unable to sustain lactation while fasting [72]. It appears that maternal size in harbor seals constrains the proportion of body fat that can be stored [73]. Furthermore, lactating harbor seals depleted 33% of their body mass during the first 80% of the nursing period and depleted their body reserves faster than other phocids [72]. A limited amount of energy stored coupled with rapid energy depletion during lactation cannot be sustained without feeding [69]. It has been suggested that it is likely that half of the phocid species may feed during lactation [6]; however, whether this occurs only in

In conclusion, lactating phocid produces great amount of energy in the form of very rich lipid milk that is transferred to the pup in a short time, and this energy is deposited as body reserves to be mobilized during the postweaning period. In addition, the pup is able to rapidly assimilate the lipid-rich milk and deposit the lipid in the blubber which is crucial for insulation and for postweaning energy reserves. The needs of the neonate seem to parallel the milk composition, and most phocids appear to follow the same trends. Some evidence has shown that not all phocid species are fast for the entire lactation period. Small body size phocids are unable to endure the cost of lactation and maternal metabolism solely with her body energy reserves and must forage to regain energy. These species of phocid have

Data on changes in milk composition throughout the whole lactation period for 6 out of 16 otariid species have been investigated [2, 3, 5, 10, 30, 190]. The general trend in these species is that milk fat concentration increases progressively, whereas protein content remains fairly constant throughout the lactation period. Less complete, but otherwise useful, data are available from northern fur seals [191], New

Increase in foraging trip duration related to stage of lactation and/or change in food availability [1, 163, 164] may influence variation in milk composition during lactation. It is possible that there is a combination between the effect of stage of lactation and foraging trip duration on the composition of milk. Stage of lactation was responsible for most of the changes observed in milk composition of subantarctic fur seals [10]; however, in Antarctic fur seals and Australian sea lions, stage of lactation was responsible for only a small proportion of the changes in milk

Zealand sea lions [82], Galapagos fur seals, and Galapagos sea lions [21].

coincide with the time the young is less dependent on free water [94].

Lactation in Farm Animals - Biology, Physiological Basis, Nutritional Requirements…

the smaller phocid species is still to be investigated.

adopted an "otariid-like foraging strategy."

4.3.2 Sea lion and fur seals (otariids)

22

composition [3, 28]. Kretzman et al. [28] and Gales et al. [2] found high variability in milk lipid concentration between and within individual Australian sea lions. However, they were unable to identify which factors contributed most to the variation in milk composition. In Antarctic fur seals, days postpartum and maternal mass contributed to the variation in milk lipid, and it was suggested that foraging trip duration also explained some of the variation [3]. These authors have recognized that extensive and systematic sampling is needed in order to describe milk composition in otariids and control for intraspecific variation in milk composition [3, 28].

The trend in changes in otariid milk composition during lactation is as follows: milk lipid and gross energy concentration increases during the first stages of lactation and peaks at mid-lactation and then decreases in the course of later stages of lactation (Table 4). Water content in milk changes inversely with milk lipid concentration, while milk protein concentration stays somewhat unchanged throughout the lactation period [10]. Although not all otariid species follow these trends, Galapagos fur seals, for example, produce milk that decreases in fat concentration with pup age in early lactation [21], and hence in the course of the perinatal period, they use their body fat storage to secrete lipid-rich milk. This has some advantages as the mother can conserve body water and the neonate is able to build up the layer of blubber that will act as insulation layer and energy reserve for the approaching period of fasting. The mother's water balance enhances at the start of the foraging trip, and on her return, she nurses the pup with a diluted milk that meliorate the pup's capacity to deal with the high temperatures at the Galapagos Islands [21].

Protein concentration in milk of Antarctic fur seals declined in 1 year but heightened in the following 2 years [3] but did not changed in Australian fur seals [30]. The increase of milk protein concentration during lactation may respond to the need to incorporate essential nutrient for pup growth. The proportions of the total protein in milk of whey and casein changed in the milk are produced by Galapagos fur seals at early and mid-lactation (40–25%, 60–75%, respectively) [83]. The reason and connotation for the changes in the proportions of whey and casein of the total protein in milk of Galapagos fur seals remain to be elucidated.

Increment in fat and energy concentration of milk at early lactation has been related with increment in the duration of foraging trips and/or the stage of lactation in some species of otariids [2, 3, 9, 30, 191]. However, in some species the foraging trip duration was not related to changes in milk composition; hence, it is possible that other mechanisms may be acting. After the long and energydemanding perinatal period, the mother must replenish energy reserves and enhance body condition, in order to produce a higher-lipid concentrated milk at early lactation [18, 140]. Maternal body condition had a significant effect on milk lipid in subantarctic fur seals [10] and New Zealand sea lions [82], but it is not known whether this applies to other otariid species. The increasing demands of the growing pup may affect the maternal response and increase milk fat concentration [10].

By the last month of the lactation period, milk lipid content tends to decrease as shown in Australian sea lions and Australian fur seals and subantarctic fur seals [2, 10, 30]. In subantarctic fur seals, the data suggested that the relationship between milk lipid concentration and at the end of the lactation stage was best described by an asymptotic relationship, i.e., decrease in lipid content. The decrease in milk lipid concentration, i.e., lower rate of energy transfer to the pup, at the end of lactation could be associated with the proximity to the pup's weaning process and higher-energy demands of gestation [10, 30]. This argument was supported by a

study on subantarctic fur seals that showed that the mother directed their body reserves toward gestation and not to milk production [27].

The stage of lactation influences the milk composition in pinnipeds [117], but there are factors that may also affect its composition. Maternal reproductive success in pinniped, i.e., success in rearing her pup, is directly influenced by her performance during lactation, and the survival of the offspring depends on the quality

(energy content) and quantity of milk produced by the mother.

Lactation Strategies and Milk Composition in Pinnipeds DOI: http://dx.doi.org/10.5772/intechopen.85386

Author details

25

Federico German Riet Sapriza

Proyecto Franca Austral, Montevideo, Uruguay

provided the original work is properly cited.

\*Address all correspondence to: frietsapriza@gmail.com

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

For the Antarctic fur seals, the rate of milk production decreased by the end of lactation [192, 193]; however, a concurrent decrease in milk lipid concentration has not been reported in late lactation [3]. The short lactation period (4 months) in this species and mothers not actively gestating an offspring (delayed implantation) during this period put less pressure to meet the energy demands of lactation and gestation [194]. In this context the mother is able to allocate energy resources to milk production, and the quality of milk lipid remains unaltered [30].

#### 5. General conclusion

There are three lactation strategies adopted by pinnipeds: a fasting strategy, foraging strategy, and aquatic strategy. Phocids have shortened the duration of lactation remarkably and reduced the time the pup and mother are exposed to the conditions of the terrestrial environments. Due to the shortage of lactation duration in phocids, the daily energy output is greater than in otariids, and phocids secrete very rich energy-dense milk. Producing milk high in solid content attenuates the impact of water stress in phocids' mother that is fasting during lactation. However, some phocid species with small maternal body size have adopted a strategy similar to that seen in otariids and feed during lactation probably due to the high-energy cost to sustain the short lactation period. Walruses have evolved to nurse and feed without separating the mother from the pup in the so-called aquatic lactation strategy. The lactation duration in walruses is very prolonged (up to 3 years) which increments the chances of pup survival. Otariids also have long lactation periods, and the rate of pup growth is slower than in phocids. The concentration of milk lipid ranges greatly among pinniped species, and the absence or presence of traces of lactose in their milk may be associated with the evolution of lactation strategy in pinnipeds.

The stage of lactation, attendance pattern, and maternal body condition are factors that influence the milk composition throughout the lactation in otariids.

In order to make interspecies comparison, the milk composition values at midlactation should be used, since they represent the peak maximum production [117] and be limited to species for which similar data are available [2]. Researches that have collected milk samples from lactating otariids throughout the lactation period are limited. Attempting to compare the milk composition among pinnipeds is a difficult task due to the lack and poor quality of the data, small sample size, and being unrepresentative of the whole lactation period.

Lactation is a crucial part of the life history of mammals and is of particular interest in pinniped as they have adopted unique lactation strategies among mammals. In order to study lactation, the milk composition and amount of milk secreted are important parameters that need to be measured adequately.

The data reviewed in this chapter has demonstrated that data on the milk composition of pinnipeds is limited but nevertheless valuable. And that there are logistical constraints working in remote field sites, and with wild animals such as pinnipeds making the collection of milk samples difficult. In addition different analytical methods have been used, and the effect of stage of lactation among other factors is often not considered or mentioned in the literature [5, 195]. In lactation studies of pinnipeds, the lack of extensive sampling has made interspecific comparisons difficult. For otariid species, milk composition has been analyzed throughout the entire lactation period (in only three species) [2, 10, 30] and for interannual variation [3, 82, 196].

Lactation Strategies and Milk Composition in Pinnipeds DOI: http://dx.doi.org/10.5772/intechopen.85386

study on subantarctic fur seals that showed that the mother directed their body

Lactation in Farm Animals - Biology, Physiological Basis, Nutritional Requirements…

milk production, and the quality of milk lipid remains unaltered [30].

For the Antarctic fur seals, the rate of milk production decreased by the end of lactation [192, 193]; however, a concurrent decrease in milk lipid concentration has not been reported in late lactation [3]. The short lactation period (4 months) in this species and mothers not actively gestating an offspring (delayed implantation) during this period put less pressure to meet the energy demands of lactation and gestation [194]. In this context the mother is able to allocate energy resources to

There are three lactation strategies adopted by pinnipeds: a fasting strategy, foraging strategy, and aquatic strategy. Phocids have shortened the duration of lactation remarkably and reduced the time the pup and mother are exposed to the conditions of the terrestrial environments. Due to the shortage of lactation duration in phocids, the daily energy output is greater than in otariids, and phocids secrete very rich energy-dense milk. Producing milk high in solid content attenuates the impact of water stress in phocids' mother that is fasting during lactation. However, some phocid species with small maternal body size have adopted a strategy similar to that seen in otariids and feed during lactation probably due to the high-energy cost to sustain the short lactation period. Walruses have evolved to nurse and feed without separating the mother from the pup in the so-called aquatic lactation strategy. The lactation duration in walruses is very prolonged (up to 3 years) which increments the chances of pup survival. Otariids also have long lactation periods, and the rate of pup growth is slower than in phocids. The concentration of milk lipid ranges greatly among pinniped species, and the absence or presence of traces of lactose in their milk may be associated with the evolution of lactation strategy

The stage of lactation, attendance pattern, and maternal body condition are factors that influence the milk composition throughout the lactation in otariids. In order to make interspecies comparison, the milk composition values at midlactation should be used, since they represent the peak maximum production [117] and be limited to species for which similar data are available [2]. Researches that have collected milk samples from lactating otariids throughout the lactation period are limited. Attempting to compare the milk composition among pinnipeds is a difficult task due to the lack and poor quality of the data, small sample size, and

Lactation is a crucial part of the life history of mammals and is of particular interest in pinniped as they have adopted unique lactation strategies among mammals. In order to study lactation, the milk composition and amount of milk secreted

The data reviewed in this chapter has demonstrated that data on the milk composition of pinnipeds is limited but nevertheless valuable. And that there are logistical constraints working in remote field sites, and with wild animals such as pinnipeds making the collection of milk samples difficult. In addition different analytical methods have been used, and the effect of stage of lactation among other factors is often not considered or mentioned in the literature [5, 195]. In lactation studies of pinnipeds, the lack of extensive sampling has made interspecific comparisons difficult. For otariid species, milk composition has been analyzed throughout the entire lactation period (in only three species) [2, 10, 30] and for interannual

being unrepresentative of the whole lactation period.

are important parameters that need to be measured adequately.

reserves toward gestation and not to milk production [27].

5. General conclusion

in pinnipeds.

variation [3, 82, 196].

24

The stage of lactation influences the milk composition in pinnipeds [117], but there are factors that may also affect its composition. Maternal reproductive success in pinniped, i.e., success in rearing her pup, is directly influenced by her performance during lactation, and the survival of the offspring depends on the quality (energy content) and quantity of milk produced by the mother.

#### Author details

Federico German Riet Sapriza Proyecto Franca Austral, Montevideo, Uruguay

\*Address all correspondence to: frietsapriza@gmail.com

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Lactation in Farm Animals - Biology, Physiological Basis, Nutritional Requirements…

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[9] Goldsworthy SD, Crowley HM. The composition of the milk of antarctic (Arctocephalus gazella) and subantarctic (A. tropicalis) fur seals at Macquarie Island. Australian Journal of Zoology. 1999;47(6):593-603

[17] Oftedal OT, Iverson SJ, Boness DJ. Milk and energy intakes of suckling

Lactation Strategies and Milk Composition in Pinnipeds DOI: http://dx.doi.org/10.5772/intechopen.85386

> [25] Donohue MJ, Costa DP, Goebel E, Antonelis GA, Baker JD. Milk intake and energy expenditure of free-ranging northern fur seal, Callorhinus ursinus, pups. Physiological and Biochemical

Zoology. 2002;75(1):3-18

316-325

295-308

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attendance behaviour of sympatrically breeding Antarctic and subantarctic fur seals, Arctocephalus spp., at Macquarie Island. Polar Biology. 1999;21(5):

[27] Georges J-Y, Guinet C. Maternal care in the subantarctic fur seals on Amsterdam Island. Ecology. 2000;81(2):

[28] Kretzmann MB, Costa DP, Higgins LV, Needham DJ. Milk composition of Australian sea lions, Neophoca cinerea: Variability in lipid content. Canadian Journal of Zoology. 1991;69(10):

[29] Ochoa-Acuna H, Francis JM, Oftedal OT. Influence of long

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[31] Arnould JPY, Boyd IL. Temporal patterns of milk production in Antarctic fur seals (Arctocephalus gazella). Journal of Zoology (London). 1995;237(1):1-12

[32] Wickens P, York AE. Comparative population dynamics of fur seals. Marine Mammal Science. 1997;13(2):

[33] Stewart BS, Yochem PK. Seasonal abundance of pinnipeds at san-Nicolas

intersuckling interval on composition of milk in the Juan Fernandez fur seal, Arctocephalus philippii. Journal of Mammalogy. 1999;80(3):758-767

californianus pups in relation to sex growth and predicted maintenance requirements. Physiological Zoology.

[18] Trillmich F. Attendance and diving behavior of South American fur seal during El Niño in 1983. In: L R G, L G K, editors. Fur Seals: Maternal Strategies on Land and at Sea. Princeton: Princeton University Press; 1986. pp. 153-167

[19] Melin SR, DeLong RL, Thomason JR, VanBlaricom GR. Attendance patterns of California Sea lion (Zalophus californianus) females and pups during the non-breeding season at San Miguel Island. Marine Mammal Science. 2000;

[20] Costa DP, Croxall JP, Duck CD. Foraging energetics of Antarctic fur seals in relation to changes in prey availability. Ecology. 1989;70(3):

[21] Trillmich F, Lechner E. Milk of the Galapagos fur seal and sea lion, with a comparison of the milk of eared seals (Otariidae). Journal of Zoology. 1986;

[22] Kooyman GL, Trillmich F. Diving behavior of galapagos sea lions. In: Gentry RL, Kooyman GL, editors. Fur Seals: Maternal Strategies on Land and at Sea. Princeton; 1986. pp. 1209-1219

[23] Doidge DW, McCann TS, Croxall JP. Attendance behavior of Antarctic fur seals. In: Gentry RL, Kooyman GL, editors. Fur Seals: Maternal Strategies on Land and at Sea. Princeton: Princeton University Press; 1986. pp. 102-114

[24] Boyd IL. Foraging and provisioning in Antarctic fur seals: Interannual variability in time-energy budgets. Behavioral Ecology. 1999;10(2):198-208

California Sea lion Zalophus

1987;60(5):560-575

16(1):169-185

596-606

209:271-277

27

[10] Georges J-Y, Guinet C, Robin JP, Groscolas R. Milking strategy in subantarctic fur seals Arctocephalus tropicalis breeding on Amsterdam Island: Evidence from changes in milk composition. Physiological and Biochemical Zoology. 2001;74(4): 548-559

[11] Schulz TM, Bowen DW. The evolution of lactation strategies in pinnipeds: A phylogenetic analysis. Ecological Monographs. 2005;75(2): 159-177

[12] Boyd IL. State-dependent fertility in pinnipeds: Contrasting capital and income breeders. Functional Ecology. 2000;14(5):623-630

[13] Gentry RL, Costa DP, Croxall DP, David JP, Davis HM, Kooyman GL, et al. Synthesis and conclusion. In: Gentry RL, Kooyman GL, editors. Fur Seals: Maternal Strategies on Land and at Sea. Princeton, NJ: Princeton University Press; 1986. pp. 220-278

[14] Cane MA. Oceanographic events during El Niño. Science. 1983; 222(4629):1189-1195

[15] Barber RT, Chavez FP. Biological consequences of El Niño. Science. 1983; 222(4629):1203-1210

[16] Trillmich F, Kooyman GL, Majluf P, et al. Attendance and diving behavior of South America fur seals during El Nino in 1983. In: Gentry LR, Kooyman LG, editors. Fur Seals: Maternal Strategies on Land and at Sea. Princeton; 1986. pp. 153-167

Lactation Strategies and Milk Composition in Pinnipeds DOI: http://dx.doi.org/10.5772/intechopen.85386

[17] Oftedal OT, Iverson SJ, Boness DJ. Milk and energy intakes of suckling California Sea lion Zalophus californianus pups in relation to sex growth and predicted maintenance requirements. Physiological Zoology. 1987;60(5):560-575

References

44(6):651-657

[1] Higgins LV, Gass L. Birth to weaning: Parturition, duration of lactation, and attendance cycles of Australian sea lions (Neophoca cinerea). Canadian Journal of

Lactation in Farm Animals - Biology, Physiological Basis, Nutritional Requirements…

[9] Goldsworthy SD, Crowley HM. The composition of the milk of antarctic (Arctocephalus gazella) and subantarctic (A. tropicalis) fur seals at Macquarie Island. Australian Journal of Zoology.

[10] Georges J-Y, Guinet C, Robin JP, Groscolas R. Milking strategy in subantarctic fur seals Arctocephalus tropicalis breeding on Amsterdam Island: Evidence from changes in milk composition. Physiological and Biochemical Zoology. 2001;74(4):

[11] Schulz TM, Bowen DW. The evolution of lactation strategies in pinnipeds: A phylogenetic analysis. Ecological Monographs. 2005;75(2):

[12] Boyd IL. State-dependent fertility in pinnipeds: Contrasting capital and income breeders. Functional Ecology.

[13] Gentry RL, Costa DP, Croxall DP, David JP, Davis HM, Kooyman GL, et al. Synthesis and conclusion. In: Gentry RL,

[14] Cane MA. Oceanographic events during El Niño. Science. 1983;

[15] Barber RT, Chavez FP. Biological consequences of El Niño. Science. 1983;

[16] Trillmich F, Kooyman GL, Majluf P, et al. Attendance and diving behavior of South America fur seals during El Nino in 1983. In: Gentry LR, Kooyman LG, editors. Fur Seals: Maternal Strategies on Land and at Sea. Princeton; 1986.

Kooyman GL, editors. Fur Seals: Maternal Strategies on Land and at Sea. Princeton, NJ: Princeton University

Press; 1986. pp. 220-278

222(4629):1189-1195

222(4629):1203-1210

pp. 153-167

1999;47(6):593-603

548-559

159-177

2000;14(5):623-630

[2] Gales NJ, Costa DP, Kretzmann M. Proximate composition of Australian sea

[3] Arnould JPY, Boyd IL. Inter- and intra-annual variation in milk composition in Antarctic fur seals (Arctocephalus gazella). Physiological Zoology. 1995;68(6):1164-1180

[4] Lunn NJ, Boyd IL, Barton T, Croxall JP. Factors affecting the growth rate and mass at weaning of Antarctic fur seals at Bird Island, South Georgia. Journal of Mammalogy. 1993;74(4):908-919

[5] Oftedal OT, Boness DJ, Tedman RA. The behavior, physiology, and anatomy of lactation in the pinnipedia. In: Genoways HH, editor. Current

Mammalogy. New York: Plenum Press;

evolution of maternal care in pinnipeds new findings raise questions about the evolution of maternal feeding strategies.

[7] Bonner WN. Lactation strategies in pinnipeds: Problems for a marine mammalian group. Symposia of the Zoological Society of London. 1984;51:

[8] Ferguson SH. The influences of environment, mating habitat, and predation on evolution of pinniped lactation strategies. Journal of Mammalian Evolution. 2006;13(1):

[6] Boness DJ, Bowen WD. The

Bioscience. 1996;46(9):645-654

1987. pp. 175-221

253-272

63-82

26

Zoology. 1993;71:2047-2055

lion milk throughout the entire supra-annual lactation period. Australian Journal of Zoology. 1996; [18] Trillmich F. Attendance and diving behavior of South American fur seal during El Niño in 1983. In: L R G, L G K, editors. Fur Seals: Maternal Strategies on Land and at Sea. Princeton: Princeton University Press; 1986. pp. 153-167

[19] Melin SR, DeLong RL, Thomason JR, VanBlaricom GR. Attendance patterns of California Sea lion (Zalophus californianus) females and pups during the non-breeding season at San Miguel Island. Marine Mammal Science. 2000; 16(1):169-185

[20] Costa DP, Croxall JP, Duck CD. Foraging energetics of Antarctic fur seals in relation to changes in prey availability. Ecology. 1989;70(3): 596-606

[21] Trillmich F, Lechner E. Milk of the Galapagos fur seal and sea lion, with a comparison of the milk of eared seals (Otariidae). Journal of Zoology. 1986; 209:271-277

[22] Kooyman GL, Trillmich F. Diving behavior of galapagos sea lions. In: Gentry RL, Kooyman GL, editors. Fur Seals: Maternal Strategies on Land and at Sea. Princeton; 1986. pp. 1209-1219

[23] Doidge DW, McCann TS, Croxall JP. Attendance behavior of Antarctic fur seals. In: Gentry RL, Kooyman GL, editors. Fur Seals: Maternal Strategies on Land and at Sea. Princeton: Princeton University Press; 1986. pp. 102-114

[24] Boyd IL. Foraging and provisioning in Antarctic fur seals: Interannual variability in time-energy budgets. Behavioral Ecology. 1999;10(2):198-208 [25] Donohue MJ, Costa DP, Goebel E, Antonelis GA, Baker JD. Milk intake and energy expenditure of free-ranging northern fur seal, Callorhinus ursinus, pups. Physiological and Biochemical Zoology. 2002;75(1):3-18

[26] Goldsworthy SD. Maternal attendance behaviour of sympatrically breeding Antarctic and subantarctic fur seals, Arctocephalus spp., at Macquarie Island. Polar Biology. 1999;21(5): 316-325

[27] Georges J-Y, Guinet C. Maternal care in the subantarctic fur seals on Amsterdam Island. Ecology. 2000;81(2): 295-308

[28] Kretzmann MB, Costa DP, Higgins LV, Needham DJ. Milk composition of Australian sea lions, Neophoca cinerea: Variability in lipid content. Canadian Journal of Zoology. 1991;69(10): 2556-2561

[29] Ochoa-Acuna H, Francis JM, Oftedal OT. Influence of long intersuckling interval on composition of milk in the Juan Fernandez fur seal, Arctocephalus philippii. Journal of Mammalogy. 1999;80(3):758-767

[30] Arnould JPY, Hindell MA. The composition of Australian fur seal (Arctocephalus pusillus doriferus) milk throughout lactation. Physiological and Biochemical Zoology. 1999;72(5): 605-612

[31] Arnould JPY, Boyd IL. Temporal patterns of milk production in Antarctic fur seals (Arctocephalus gazella). Journal of Zoology (London). 1995;237(1):1-12

[32] Wickens P, York AE. Comparative population dynamics of fur seals. Marine Mammal Science. 1997;13(2): 241-292

[33] Stewart BS, Yochem PK. Seasonal abundance of pinnipeds at san-Nicolas Island California USA 1980–1982. Bulletin of the Southern California Academy of Sciences. 1984;83(3): 121-132

[34] Trillmich F, Majluf P. First observations on the colony structure behavior and vocal repertoire of the South American fur seal Arctocephalus australis in Peru. Zeitschrift Für Säugetierkunde. 1981;46(5):310-322

[35] Francis J, Boness D, Ochoa-Acuna H. A protracted foraging and attendance cycle in female Juan Fernandez fur seals. Marine Mammal Science. 1998;14(3): 552-574

[36] Georges J-Y, Sevot X, Guinet C. Fostering in a subantarctic fur seal. Mammalia. 1999;63(3):384-388

[37] Higgins LV, Costa DP, Huntley AC, Le Boeuf BJ. Behavioral and physiological measurements of maternal investment in the Steller Sea lion Eumetopias jubatus. Marine Mammal Science. 1988;4(1):44-58

[38] Pitcher KW, Burkanov VN, Calkins DG, Le BBJ, Mamaev EG, Merrick RL, et al. Spatial and temporal variation in the timing of births of Steller Sea lions. Journal of Mammalogy. 2001;82(4): 1047-1053

[39] Pitcher KW, Calkins DG. Reproductive biology of Steller Sea lions Eumetopias jubatus in the Gulf of Alaska USA. Journal of Mammalogy. 1981; 62(3):599-605

[40] Mattlin RH, Gales NJ, Costa DP. Seasonal dive behaviour of lactating New Zealand fur seals (Arctocephalus forsteri). Canadian Journal of Zoology. 1998;76(2):350-360

[41] Goldsworthy SD, Shaughnessy PD. Breeding biology and haul-out pattern of the New Zealand fur seal, Arctocephalus forsteri, at Cape

Gantheaume, South Australia. Wildlife Research. 1994;21(3):365-376

[50] Shaughnessy PD, Kerry KR. Crabeater seals Lobodon-Carcinophagus during the breeding season observations on five groups near Enderby Land Antarctica. Marine Mammal Science.

Lactation Strategies and Milk Composition in Pinnipeds DOI: http://dx.doi.org/10.5772/intechopen.85386

> No 5. Rome: Food and Agriculture Organization of the United Nations;

[59] Hindell MA, Bryden MM, Burton HR. Early growth and milk composition in southern elephant seals (Mirounga leonina). Australian Journal of Zoology.

[60] Laws RM. Southern elephant seal. In: Mammals in the Sea Pinnipeds Species Summaries and Report on Sirenians. Rome: Food and Agriculture Organization of the United Nations;

[61] Riedman M, Ortiz CL. Changes in milk composition during lactation in the northern elephant seal. Physiological

Zoology. 1979;52(2):240-249

[62] Puppione DL, Kuehlthau CM, Jandacek RJ, Costa DP. Chylomicron triacylglycerol fatty acids in suckling northern elephant seals (Mirounga angustirostris) resemble the composition and the distribution of fatty acids in milk fat. Comparative Biochemistry and

Physiology Part B: Comparative Biochemistry. 1996;114(1):53-57

1979. pp. 58-63

1979. pp. 104-105

Press; 1981. pp. 195-220

[63] Bonner WN. Harbour (common) seal. In: Mammals in the Sea FAO Fish Series No 5. Rome: Food and Agriculture Organization of the United Nations;

[64] Brenton C. Hawaiian monk seal. In: Mammals in the Sea FAO Fish Series No

[65] Kenyon KW. Monk seals. In: Ridway SH, Harrison RJ, editors. Handbook of Marine Mammals. London: Academic

[66] Boulva J. Mediterranean monk seal. In: Mammals in the Sea FAO Fish Series No 5. Rome: Food and Agriculture

5. Rome: Food and Agriculture Organization of the United Nations;

1979. pp. 72-73

1994;42(6):723-732

1979. pp. 106-109

[51] Iverson SJ, Bowen WD, Boness DJ, Oftedal OT. The effect of maternal size and milk energy output on pup growth in grey seals (Halichoerus grypus). Physiological Zoology. 1993;

[52] Burns JJ. Ribbon seal-phoca fasciata. In: Ridways HH, Harrison RJ, editors. Handbook of Marine Mammals. New York: Academic Press; 1981. pp. 89-109

[53] Bonner W, Largha seal N. Mammals in the Sea FAO Fish Series No 5. Rome: Food and Agriculture Organization of the United Nations; 1979. pp. 63-65

[54] Gjertz I, Kovacs KM, Lydersen C, Wiig O. Movements and diving of bearded seal (Erignathus barbatus) mothers and pups during lactation and post-weaning. Polar Biology. 2000

[55] Hofman RJ. Leopard seal. In: Mammals in the Sea Pinnipeds Species Summaries and Report on Sirenians.

Organization of the United Nations;

[56] De Master DP. Weddell seal. In: Mammals in the Sea FAO Fish Series No.

[57] Hammill MO, Lydersen C, Ryg M, Smith TG. Lactation in the ringed seal Phoca-Hispida. Canadian Journal of Fisheries and Aquatic Sciences. 1991;

Mammals in the Sea FAO Fish Series

5. Rome: Food and Agriculture Organization of the United Nations;

Rome: Food and Agriculture

August;23(8):559-566

1979. pp. 125-129

1979. pp. 130-134

48(12):2471-2476

29

[58] Popov L. Baikal seal. In:

1989;5(1):68-77

66(1):61-88

[42] Cawthorn MW. Part II species accounts. In: King CM, editor. The Handbook of New Zealand Mammals. 1st ed. Auckland: Oxford University Press; 1990. pp. 256-262

[43] David JHM, Rand RW. Attendance behavior of South African fur seals. In: Gentry RL, Kooyman GL, editors. Fur Seals: Maternal Strategies on Land and at Sea. Princeton: Princeton University Press; 1986. pp. 126-141

[44] Kovacs KM, Lavigne DM. Maternal investment in otariid seals and walruses. Canadian Journal of Zoology. 1992; 70(10):1953-1964

[45] Hammill MO, Smith TG. The role of predation in the ecology of the ringed real in Barrow Strait Northwest Territories Canada. Marine Mammal Science. 1991;1(2):123-135

[46] Bowen WD. Behavioural ecology of pinnipeds neonates. In: Renouf D, editor. The Behaviour of Pinnipeds. London: Chapman and Hall; 1991. pp. 66-127

[47] Bowen WD, Oftedal OT, Boness DJ. Birth to weaning in 4 days: Remarkable growth in the hooded seal, Cystophora cristata. Canadian Journal of Zoology. 1985;63(12):2841-2846

[48] Oftedal OT, Bowen WD, Boness D, et al. Energy transfer by lactating hooded seals and nutrient deposition in their pups during the four days from birth to weaning. Physiological Zoology. 1993;66(3):412-436

[49] Kovacs KM, Lavigne DM. Neonatal growth and organ allometry of Northwest Atlantic harp seals (Phoca groenlandica). Canadian Journal of Zoology. 1985;63:2793-2799

Lactation Strategies and Milk Composition in Pinnipeds DOI: http://dx.doi.org/10.5772/intechopen.85386

[50] Shaughnessy PD, Kerry KR. Crabeater seals Lobodon-Carcinophagus during the breeding season observations on five groups near Enderby Land Antarctica. Marine Mammal Science. 1989;5(1):68-77

Island California USA 1980–1982. Bulletin of the Southern California Academy of Sciences. 1984;83(3):

Lactation in Farm Animals - Biology, Physiological Basis, Nutritional Requirements…

Gantheaume, South Australia. Wildlife

[43] David JHM, Rand RW. Attendance behavior of South African fur seals. In: Gentry RL, Kooyman GL, editors. Fur Seals: Maternal Strategies on Land and at Sea. Princeton: Princeton University

[44] Kovacs KM, Lavigne DM. Maternal investment in otariid seals and walruses. Canadian Journal of Zoology. 1992;

[45] Hammill MO, Smith TG. The role of predation in the ecology of the ringed real in Barrow Strait Northwest Territories Canada. Marine Mammal

[46] Bowen WD. Behavioural ecology of pinnipeds neonates. In: Renouf D, editor. The Behaviour of Pinnipeds. London: Chapman and Hall; 1991.

[47] Bowen WD, Oftedal OT, Boness DJ. Birth to weaning in 4 days: Remarkable growth in the hooded seal, Cystophora cristata. Canadian Journal of Zoology.

[48] Oftedal OT, Bowen WD, Boness D, et al. Energy transfer by lactating hooded seals and nutrient deposition in their pups during the four days from birth to weaning. Physiological Zoology.

[49] Kovacs KM, Lavigne DM. Neonatal

growth and organ allometry of Northwest Atlantic harp seals (Phoca groenlandica). Canadian Journal of Zoology. 1985;63:2793-2799

Research. 1994;21(3):365-376

Press; 1990. pp. 256-262

Press; 1986. pp. 126-141

Science. 1991;1(2):123-135

1985;63(12):2841-2846

1993;66(3):412-436

70(10):1953-1964

pp. 66-127

[42] Cawthorn MW. Part II species accounts. In: King CM, editor. The Handbook of New Zealand Mammals. 1st ed. Auckland: Oxford University

[34] Trillmich F, Majluf P. First observations on the colony structure behavior and vocal repertoire of the South American fur seal Arctocephalus australis in Peru. Zeitschrift Für Säugetierkunde. 1981;46(5):310-322

[35] Francis J, Boness D, Ochoa-Acuna H. A protracted foraging and attendance cycle in female Juan Fernandez fur seals. Marine Mammal Science. 1998;14(3):

[36] Georges J-Y, Sevot X, Guinet C. Fostering in a subantarctic fur seal. Mammalia. 1999;63(3):384-388

[37] Higgins LV, Costa DP, Huntley AC,

physiological measurements of maternal investment in the Steller Sea lion Eumetopias jubatus. Marine Mammal

[38] Pitcher KW, Burkanov VN, Calkins DG, Le BBJ, Mamaev EG, Merrick RL, et al. Spatial and temporal variation in the timing of births of Steller Sea lions. Journal of Mammalogy. 2001;82(4):

Reproductive biology of Steller Sea lions Eumetopias jubatus in the Gulf of Alaska USA. Journal of Mammalogy. 1981;

[40] Mattlin RH, Gales NJ, Costa DP. Seasonal dive behaviour of lactating New Zealand fur seals (Arctocephalus forsteri). Canadian Journal of Zoology.

[41] Goldsworthy SD, Shaughnessy PD. Breeding biology and haul-out pattern

of the New Zealand fur seal, Arctocephalus forsteri, at Cape

Le Boeuf BJ. Behavioral and

Science. 1988;4(1):44-58

[39] Pitcher KW, Calkins DG.

1047-1053

62(3):599-605

1998;76(2):350-360

28

121-132

552-574

[51] Iverson SJ, Bowen WD, Boness DJ, Oftedal OT. The effect of maternal size and milk energy output on pup growth in grey seals (Halichoerus grypus). Physiological Zoology. 1993; 66(1):61-88

[52] Burns JJ. Ribbon seal-phoca fasciata. In: Ridways HH, Harrison RJ, editors. Handbook of Marine Mammals. New York: Academic Press; 1981. pp. 89-109

[53] Bonner W, Largha seal N. Mammals in the Sea FAO Fish Series No 5. Rome: Food and Agriculture Organization of the United Nations; 1979. pp. 63-65

[54] Gjertz I, Kovacs KM, Lydersen C, Wiig O. Movements and diving of bearded seal (Erignathus barbatus) mothers and pups during lactation and post-weaning. Polar Biology. 2000 August;23(8):559-566

[55] Hofman RJ. Leopard seal. In: Mammals in the Sea Pinnipeds Species Summaries and Report on Sirenians. Rome: Food and Agriculture Organization of the United Nations; 1979. pp. 125-129

[56] De Master DP. Weddell seal. In: Mammals in the Sea FAO Fish Series No. 5. Rome: Food and Agriculture Organization of the United Nations; 1979. pp. 130-134

[57] Hammill MO, Lydersen C, Ryg M, Smith TG. Lactation in the ringed seal Phoca-Hispida. Canadian Journal of Fisheries and Aquatic Sciences. 1991; 48(12):2471-2476

[58] Popov L. Baikal seal. In: Mammals in the Sea FAO Fish Series No 5. Rome: Food and Agriculture Organization of the United Nations; 1979. pp. 72-73

[59] Hindell MA, Bryden MM, Burton HR. Early growth and milk composition in southern elephant seals (Mirounga leonina). Australian Journal of Zoology. 1994;42(6):723-732

[60] Laws RM. Southern elephant seal. In: Mammals in the Sea Pinnipeds Species Summaries and Report on Sirenians. Rome: Food and Agriculture Organization of the United Nations; 1979. pp. 106-109

[61] Riedman M, Ortiz CL. Changes in milk composition during lactation in the northern elephant seal. Physiological Zoology. 1979;52(2):240-249

[62] Puppione DL, Kuehlthau CM, Jandacek RJ, Costa DP. Chylomicron triacylglycerol fatty acids in suckling northern elephant seals (Mirounga angustirostris) resemble the composition and the distribution of fatty acids in milk fat. Comparative Biochemistry and Physiology Part B: Comparative Biochemistry. 1996;114(1):53-57

[63] Bonner WN. Harbour (common) seal. In: Mammals in the Sea FAO Fish Series No 5. Rome: Food and Agriculture Organization of the United Nations; 1979. pp. 58-63

[64] Brenton C. Hawaiian monk seal. In: Mammals in the Sea FAO Fish Series No 5. Rome: Food and Agriculture Organization of the United Nations; 1979. pp. 104-105

[65] Kenyon KW. Monk seals. In: Ridway SH, Harrison RJ, editors. Handbook of Marine Mammals. London: Academic Press; 1981. pp. 195-220

[66] Boulva J. Mediterranean monk seal. In: Mammals in the Sea FAO Fish Series No 5. Rome: Food and Agriculture

Organization of the United Nations; 1979. pp. 95-100

[67] Kovacs KM, Lavigne DM, Innes S. Mass transfer efficiency between harp seal Phoca groenlandica mothers and their pups during lactation. Journal of Zoology. 1991;223(2):213-222

[68] Lydersen C, Kovacs KM. Behaviour and energetics of ice-breeding, North Atlantic phocid seals during the lactation period. Marine Ecology Progress Series. 1999;187:265-281

[69] Bowen WD, Iverson SJ, Boness DJ, Oftedal OT. Foraging effort, food intake and lactation performance depend on maternal mass in a small phocid seal. Functional Ecology. 2001 June;15(3): 325-334

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1978;185:469-476

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[96] Oftedal OT, Bowen WD, Boness DJ. Lactation performance and nutrient deposition in pups of the harp

seal, Phoca groenlandica, on ice floes off Southeast Labrador. Physiological Zoology. 1996;69(3):635-657

[97] Oftedal OT, Boness DJ, Bowen WD.

The composition of hooded seal (Cystophora cristata) milk: An adaptation for postnatal fattening. Canadian Journal of Zoology. 1988;

[98] Baker JR. Grey seal (Halichoerus grypus) milk composition and its variation over lactation. The

British Veterinary Journal. 1990;146:

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Composition. Storrs: Academic Press;

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Organization of the United Nations;

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Science. 1996;12(2):313-317

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166-178

74:1-279

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Comparative Physiology B: Biochemical,

[71] Kelley BP, Wartzok D. Ringed seal diving behavior in the breeding season. Canadian Journal of Zoology. 1996;

[72] Bowen WD, Oftedal OT, Boness DJ.

[73] Boness DJ, Bowen WD, Oftedal OT. Evidence of a maternal foraging cycle resembling that of otariid seals in a small phocid, the harbor seal. Behavioral Ecology and Sociobiology. 1994;34(2):

Mass and energy transfer during lactation in a small phocid the harbor seal Phoca vitulina. Physiological Zoology. 1992;65(4):844-866

[74] Oftedal OT. Use of maternal reserves as a lactation strategy in large mammals. The Proceedings of the Nutrition Society. 2000;59(1):99-106

Systemic, and Environmental Physiology. 1996;166(7):405-411

74(8):1547-1555

95-104

30

Zoology. 1991;223(2):213-222

1979. pp. 95-100

325-334

[84] Peaker M, Goode JA. The milk of the fur-seal, Arctocephalus tropicalis gazella; in particular the composition of the aqueous phase. Journal of Zoology. 1978;185:469-476

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[86] Dosako S, Taneya S, Kimura T, Ohmori T, Daikoku H, Suzuki N, et al. Milk of northern fur seal: Composition, especially carbohydrate and protein. Journal of Dairy Science. 1983;66: 2076-2083

[87] Jenness R. The composition of milk. In: L B L, R V S, editors. Lactation: A Comprehensive Treatise. New York: Academic Press; 1974. pp. 3-107

[88] Ling ER, Kon SK, Porter JWG. The composition of milk and the nutritive value of its components. In: Kon SK, Cowie AT, editors. Milk: The Mammary Gland and its Secretion. New York: Academic Press; 1961

[89] Johnson AH. The composition of milk. In: Webb BE, Johnson AH, Alford JA, editors. Fundamentals of Dairy Chemistry. Westport, Connecticut: AVI Publishing; 1974. pp. 1-57

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[91] Jenness R, Sloan RE. The composition of milks of various species: A review. Dairy Science Abstracts. 1970; 32(10):599-612

[92] Linzell JL. Milk yield, energy loss in milk, and mammary gland weight in different species. Dairy Science Abstracts. 1972;34(5):351-360

[93] Cook HW, Baker BE. Seal milk. I. Harp seal (Pagophilus groenlandica) composition and pesticide residue content. Canadian Journal of Zoology. 1969;47:1129-1132

[94] Lavigne DM, Stewart REA, Fletcher F. Changes in composition and energy content of harp seal milk during lactation. Physiological Zoology. 1982; 55(1):1-9

[95] Webb BE, Stewart REA, Lavigne DM. Mineral constituents of harp seal milk. Canadian Journal of Zoology. 1984;62(5):831-833

[96] Oftedal OT, Bowen WD, Boness DJ. Lactation performance and nutrient deposition in pups of the harp seal, Phoca groenlandica, on ice floes off Southeast Labrador. Physiological Zoology. 1996;69(3):635-657

[97] Oftedal OT, Boness DJ, Bowen WD. The composition of hooded seal (Cystophora cristata) milk: An adaptation for postnatal fattening. Canadian Journal of Zoology. 1988; 66(2):318-322

[98] Baker JR. Grey seal (Halichoerus grypus) milk composition and its variation over lactation. The British Veterinary Journal. 1990;146: 233-238

[99] Oftedal OT, Iverson SJ. Comparative analysis of nonhuman milks: A phylogenetic variation in the gross composition of milk. In: Jensen RG, editor. Handbook of Milk Composition. Storrs: Academic Press; 1995. pp. 749-780

[100] Tedman R, Green B. Water and sodium fluxes and lactational energetics in suckling pups of Weddell seals

(Leptonychotes weddellii). Journal of Zoology. 1987;212:29-42

[101] Carlini AR, Marquez MEI, Soave G, Vergani DF, Ronayne DFPA. Southern elephant seal, Mirounga leonina: Composition of milk during lactation. Polar Biology. 1994;14(1):37-42

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[103] Green B, Fogerty A, Libke J, Newgrain K, Shaughnessy P. Aspects of lactation in the crabeater seal (Lobodon carcinophagus). Australian Journal of Zoology. 1993;41:203-213

[104] Jenness R. Comparative aspects of milk proteins. The Journal of Dairy Research. 1979;46:197-210

[105] Pilson MEQ , Kelly AL. Composition of the milk from Zalophus californianus, the California Sea lion. Science. 1962;135:104-105

[106] Stewart REA, Webb BE, Lavigne DM, Fletcher F. Determining lactose content of harp seal milk. Canadian Journal of Zoology. 1983;61:1094-1100

[107] Shaughnessy PD. An electrophoretic study of blood and milk proteins of the southern elephant seal, Mirounga leonina. Journal of Mammalogy. 1974;55:796-808

[108] Ashworth US, Ramaiah GD, Keyes MC. Species differences in the composition of milk with special reference to the northern fur seal. Journal of Dairy Science. 1966;49: 1206-1211

[109] Davis TA, Nguyen HV, Costa DP, Reeds PJ. Amino acid composition of pinniped milk. Comparative

Biochemistry and Physiology. Part B, Biochemistry & Molecular Biology. 1995;110(3):633-639

Physiology. Part A, Molecular & Integrative Physiology. 2003;135A(4):

yield and energy output at peak lactation: A comparative review. Symposia of the Zoological Society of

[118] Pilson MEQ. Absence of lactose from the milk of the Otariodea, a superfamily of marine mammals. American Zoologist. 1965;5:120

[119] Schmidt DV, Walker LE, Ebner KE. Lactose synthetase activity in northern fur seal milk. Biochimica et Biophysica

[120] Johnson JF, Christiansen RO, Kretchmer N. Lactose synthetase in mammary gland of the California Sea lion. Biochemical and Biophysical Research Communications. 1972;47:

[121] Peaker M. The aqueous phase of milk: Ion and water transport. Symposia of the Zoological Society of London.

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144(3620):850-851

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[128] Jenness R, Williams TD, Mullin RJ. Composition of milk of the sea otter

[130] Gregory ME, Kon SK, Rowland SJ, Thompson SY. The composition of the milk of the blue whale. The Journal of Dairy Research. 1955;22:108-112

[131] Jenness R, Odell DK. Composition of milk of the pygmy sperm whale (Kogia breviceps). Comparative

Biochemistry and Physiology. 1978;61A:

[132] Oftedal OT. Interspecies variation in milk composition among horses, zebras and asses (Perissodactyla: Equidae). The Journal of Dairy Research. 1988;55(1):57-66

[133] Trillmich F. Parental investment in pinnipeds. Advances in the Study of

[134] Oftedal O. Lactation strategies with emphasis on pinnipeds. Journal of Dairy

Behaviour. 1996;25:533-577

Science. 1992;75(1):169

Zoology. 1998;76(5):978-983

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Physiology. Part A, Molecular & Integrative Physiology. 2003;135A(4): 549-563

(Leptonychotes weddellii). Journal of

[101] Carlini AR, Marquez MEI, Soave G, Vergani DF, Ronayne DFPA. Southern elephant seal, Mirounga leonina: Composition of milk during lactation. Polar Biology. 1994;14(1):37-42

Biochemistry and Physiology. Part B, Biochemistry & Molecular Biology.

[110] Davis TA, Nguyen HV, Garcia-Bravo R, Fiorotto ML, Jackson EM, Reeds PJ. Amino acid composition of the milk of some mammalian species changes with stage of lactation. The British Journal of Nutrition. 1994;72(6):

[111] Urashima T, Saito T, Nakamura T, Messer M. Oligosaccharides of milk and colostrum in non-human mammals. Glycoconjugate Journal. 2001;18(5):

[112] Jenness R, Regehr EA, Sloan RE. Comparative biochemical studies of milks-II. Dialyzable carbohydrates. Comparative Biochemistry and Physiology. 1964;13(4):339-352

[113] Newburg DS, Neubauer SH. Handbook of Milk Composition. New

[114] Urashima T, Arita M, Yoshida M, Nakamura T, Arai I, Saito T, et al. Chemical characterisation of the oligosaccharides in hooded seal

(Cystophora cristata) and Australian fur seal (Arctocephalus pusillus doriferus) milk. Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology. 2001;128(2):307-323

[115] Urashima T, Hiramatsu Y, Murata

milk of the crabeater seal (Lobodon carcinophagus). Comparative

Biochemistry and Physiology Part B: Biochemistry and Molecular Biology.

Yamaguchi K, Munakata J, Arai I, Saito T, et al. Chemical characterization of the oligosaccharides in milk of high Arctic harbour seal (Phoca vitulina vitulina). Comparative Biochemistry and

[116] Urashima T, Nakamura T,


S, Nakamura T, Messer M.

Identification of 2<sup>0</sup>

1997;116(3):311-314

York: Academic Press; 1995

1995;110(3):633-639

845-853

Lactation in Farm Animals - Biology, Physiological Basis, Nutritional Requirements…

357-371

[102] Messer M, Crisp EA, Newgrain K. Studies on the carbohydrate content of milk of the crabeater seal (Lobodon carcinophagus). Comparative

Biochemistry and Physiology Part B: Comparative Biochemistry. 1988;90B

[103] Green B, Fogerty A, Libke J, Newgrain K, Shaughnessy P. Aspects of lactation in the crabeater seal (Lobodon carcinophagus). Australian Journal of

[104] Jenness R. Comparative aspects of milk proteins. The Journal of Dairy

Composition of the milk from Zalophus californianus, the California Sea lion.

[106] Stewart REA, Webb BE, Lavigne DM, Fletcher F. Determining lactose content of harp seal milk. Canadian Journal of Zoology. 1983;61:1094-1100

electrophoretic study of blood and milk proteins of the southern elephant seal,

[108] Ashworth US, Ramaiah GD, Keyes

[109] Davis TA, Nguyen HV, Costa DP, Reeds PJ. Amino acid composition of

Zoology. 1993;41:203-213

Research. 1979;46:197-210

[105] Pilson MEQ , Kelly AL.

Science. 1962;135:104-105

[107] Shaughnessy PD. An

Mirounga leonina. Journal of Mammalogy. 1974;55:796-808

MC. Species differences in the composition of milk with special reference to the northern fur seal. Journal of Dairy Science. 1966;49:

pinniped milk. Comparative

1206-1211

32

(2):367-370

Zoology. 1987;212:29-42

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[120] Johnson JF, Christiansen RO, Kretchmer N. Lactose synthetase in mammary gland of the California Sea lion. Biochemical and Biophysical Research Communications. 1972;47: 393-397

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[122] Crisp EA, Messer M, Shaughnessy P. Intestinal lactase and other disaccharidase activities of a suckling crabeater seal (Lobodon carcinophagus). Comparative Biochemistry and Physiology. 1988;90B(2):371-374

[123] Kretchmer N, Sunshine P. Intestinal disaccharidase deficiency in the sea lion. Gastroenterology. 1967;53: 123-129

[124] Sunshine P, Kretchmer N. Intestinal disaccharidases: Absence in two species of sea lions. Science. 1964; 144(3620):850-851

[125] Nakamura T, Urashima T, Mizukami T, Fukushima M, Arai I, Senshu T, et al. Composition and oligosaccharides of a milk sample of the giant panda, Ailuropoda melanoleuca. Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology. 2003;135B(3): 439-448

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[128] Jenness R, Williams TD, Mullin RJ. Composition of milk of the sea otter Enhydra lutris. Comparative Biochemistry and Physiology. A, Comparative Physiology. 1981;70(3): 375-380

[129] Pilson MEQ , Waller DW. Composition of the milk from spotted and spinner porpoises. Journal of Mammalogy. 1970;51:74-79

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[131] Jenness R, Odell DK. Composition of milk of the pygmy sperm whale (Kogia breviceps). Comparative Biochemistry and Physiology. 1978;61A: 383-386

[132] Oftedal OT. Interspecies variation in milk composition among horses, zebras and asses (Perissodactyla: Equidae). The Journal of Dairy Research. 1988;55(1):57-66

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> [160] Cabiddu A, Branca A, Decandia M, Pes A, Santucci PM, Masoero F, et al. Relationship between body condition score, metabolic profile, milk yield and milk composition in goats browsing a Mediterranean shrubland. Livestock Production Science. 1999;61(2-3):

> [161] Garnsworthy PC, Huggett CD. The influence of the fat concentration of the diet on the response by dairy cows to body condition at calving. Animal Production. 1992;54(1):7-13

> [162] Boltnev AI, York AE. Maternal investment in northern fur seals (Callorhinus ursinus): Interrelationships among mothers' age, size, parturition date, offspring size and sex ratios. Journal of Zoology. 2001;254(2):219-228

> [163] Lunn NJ, Boyd IL, Croxall JP. Reproductive performance of female Antarctic fur seals: The influence of age, breeding experience, environmental variation and individual quality. The Journal of Animal Ecology. 1994;63(4):

> [164] Boyd IL, Lunn NL, Barton T. Time budgets and foraging characteristics of lactating Antarctic fur seals. The Journal of Animal Ecology. 1991;60(2):

[165] Boyd IL, Arnould JPY, Barton T, Croxall JP. Foraging behaviour of Antarctic fur seals during periods of contrasting prey abundance. The Journal of Animal Ecology. 1994;63(3):

[166] Rosas FCW, Haimovici M, Pinedo MC. Age and growth of the south American sea lion, Otaria flavescens (Shaw, 1800), in southern Brazil. Journal of Mammalogy. 1993;75(1):

[167] Trites AW, Bigg MA. Physical growth of northern fur seals (Callorhinus ursinus): Seasonal

267-273

827-840

577-592

703-713

141-147

[152] Trillmich F, Limberger D. Drastic effects of El Niño on Galapagos Ecuador pinnipeds. Oecologia. 1985;67(1):19-22

[153] Purushottam S, Kiran S. Milk yield and milk composition of crossbred cows under various shelter systems. Indian Journal of Dairy Science. 2003;56(1):

[154] Martin JA, Walsh BJ, Thompson NA. Seasonal and lactational influences on bovine milk composition in New Zealand. The Journal of Dairy Research.

[155] Oftedal OT. Lactation in the dog: Milk composition and intake by

puppies. The Journal of Nutrition. 1984;

[156] Wilson LL, Gillooly JE, Rugh MC, Thompson CE, Purdy HR. Effects of energy intake, cow body size and calf sex on composition and yield of milk by Angus-Holstein cows and preweaning growth rate of progeny. Journal of Animal Science. 1969;28:789-795

[157] Agenäs S, Burstedt E, Holtenius K. Effects of feeding intensity during the dry period. 1. Feed intake, body weight, and milk production. Journal of Dairy

[158] Iverson SJ. Milk secretion in marine mammals in relation to foraging: Can milk fatty acids predict diet? Symposia of the Zoological Society of London.

[159] Brown KH, Akhtar NA, Robertson AD, Ahmed MG. Lactational capacity of

marginally nourished mothers relationships between maternal nutritional status and quantity and proximate composition of milk. Pediatrics. 1986;78(5):909-919

Science. 2003;86:870-882

1993;66:263-291

35

1987;21(2):109-118

46-50

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114:803-812

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[146] Winship AJ, Trites AW, Calkins DG. Growth in body size of the Steller Sea lion (Eumetopias jubatus). Journal of Mammalogy. 2001;82(2):500-519

[147] Boltnev AI, York AE, Antonelis GA. Northern fur seal young: Interrelationships among birth size, growth, and survival. Canadian Journal of Zoology. 1998;76(5):843-854

[148] Trites AW. Fetal growth and the condition of pregnant northern fur seal off western North America. Canadian Journal of Zoology. 1992;70:2125-2131

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26(2):151-157

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Mammals; Boston, Massachusetts. 1983.

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[139] Arnould JPY. Indices of body condition and body composition in

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female South African fur seals (Arctocephalus pusillus) in Namibia. Canadian Journal of Zoology. 1998;

76(8):1418-1424

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34

1996;239:769-782

[152] Trillmich F, Limberger D. Drastic effects of El Niño on Galapagos Ecuador pinnipeds. Oecologia. 1985;67(1):19-22

[153] Purushottam S, Kiran S. Milk yield and milk composition of crossbred cows under various shelter systems. Indian Journal of Dairy Science. 2003;56(1): 46-50

[154] Martin JA, Walsh BJ, Thompson NA. Seasonal and lactational influences on bovine milk composition in New Zealand. The Journal of Dairy Research. 1998;65:401-411

[155] Oftedal OT. Lactation in the dog: Milk composition and intake by puppies. The Journal of Nutrition. 1984; 114:803-812

[156] Wilson LL, Gillooly JE, Rugh MC, Thompson CE, Purdy HR. Effects of energy intake, cow body size and calf sex on composition and yield of milk by Angus-Holstein cows and preweaning growth rate of progeny. Journal of Animal Science. 1969;28:789-795

[157] Agenäs S, Burstedt E, Holtenius K. Effects of feeding intensity during the dry period. 1. Feed intake, body weight, and milk production. Journal of Dairy Science. 2003;86:870-882

[158] Iverson SJ. Milk secretion in marine mammals in relation to foraging: Can milk fatty acids predict diet? Symposia of the Zoological Society of London. 1993;66:263-291

[159] Brown KH, Akhtar NA, Robertson AD, Ahmed MG. Lactational capacity of marginally nourished mothers relationships between maternal nutritional status and quantity and proximate composition of milk. Pediatrics. 1986;78(5):909-919

[160] Cabiddu A, Branca A, Decandia M, Pes A, Santucci PM, Masoero F, et al. Relationship between body condition score, metabolic profile, milk yield and milk composition in goats browsing a Mediterranean shrubland. Livestock Production Science. 1999;61(2-3): 267-273

[161] Garnsworthy PC, Huggett CD. The influence of the fat concentration of the diet on the response by dairy cows to body condition at calving. Animal Production. 1992;54(1):7-13

[162] Boltnev AI, York AE. Maternal investment in northern fur seals (Callorhinus ursinus): Interrelationships among mothers' age, size, parturition date, offspring size and sex ratios. Journal of Zoology. 2001;254(2):219-228

[163] Lunn NJ, Boyd IL, Croxall JP. Reproductive performance of female Antarctic fur seals: The influence of age, breeding experience, environmental variation and individual quality. The Journal of Animal Ecology. 1994;63(4): 827-840

[164] Boyd IL, Lunn NL, Barton T. Time budgets and foraging characteristics of lactating Antarctic fur seals. The Journal of Animal Ecology. 1991;60(2): 577-592

[165] Boyd IL, Arnould JPY, Barton T, Croxall JP. Foraging behaviour of Antarctic fur seals during periods of contrasting prey abundance. The Journal of Animal Ecology. 1994;63(3): 703-713

[166] Rosas FCW, Haimovici M, Pinedo MC. Age and growth of the south American sea lion, Otaria flavescens (Shaw, 1800), in southern Brazil. Journal of Mammalogy. 1993;75(1): 141-147

[167] Trites AW, Bigg MA. Physical growth of northern fur seals (Callorhinus ursinus): Seasonal

fluctuations and migratory influences. Journal of Zoology. 1996;238(3):459-482

[168] Bengston JL, Siniff DB. Reproductive aspects of female crabeater seals (Lobodon carcinophagus) along the Antarctic peninsula. Canadian Journal of Fisheries and Aquatic Sciences. 1981;59:92-102

[169] Bryden MM. Body size and composition of elephant seals (Mirounga leonina): Absolute measurements and estimates from bone dimensions. Journal of Zoology. 1972;167:265-276

[170] Stephens DW, Krebs JR. Foraging Theory. Princeton: Princeton University Press; 1986

[171] Costa DP. Reproductive and foraging energetics of high latitude penguins, albatrosses and pinnipeds: Implications for life history patterns. American Zoologist. 1991;31:111-130

[172] Staniland IJ, Boyd IL, Reid K. An energy-distance trade-off in a centralplace forager, the Antarctic fur seal (Arctocephalus gazella). Marine Biology. 2007;152(2):233-241

[173] Peaker M, Wilde JC. Milk secretion: Autocrine control. News in Physiological Sciences. 1987;2:124-126

[174] Knight CH, Peaker M, Wilde JC. Local control of mammary development and function. Reviews of Reproduction. 1998;3:104-112

[175] Trillmich F. Attendance behavior of galapagos sea lions. In: L R G, L G K, editors. Fur Seals: Maternal Strategies on Land and at Sea. Princeton: Princeton University Press; 1986. pp. 196-208

[176] Figueroa-Carranza A. Early lactation and attendance behavior of the Guadalupe fur seal females (Arctocephalus townsendi) [MSc thesis]. Santa Cruz: University of California; 1994

[177] Antonelis GA, Stewart BS, Perryman WF. Foraging characteristics of female northern fur seals Callorhinus ursinus and California Sea lions Zalophus californianus. Canadian Journal of Zoology. 1990; 68(1):150-158

Journal of Zoology. 2007;273(2):

[185] Cook HW, Pearson AM, Simmons NM, Baker BE. Dall sheep (Ovis dalli dalli) milk. I. Effects of stage of

Lactation Strategies and Milk Composition in Pinnipeds DOI: http://dx.doi.org/10.5772/intechopen.85386

Marine Mammal Science. 1997;13(3):

[193] Arnould JPY, Boyd IL, Socha DG.

(Arctocephalus gazella) pups. Canadian Journal of Zoology. 1996;74(2):254-266

[195] Schulz TM, Bowen WD. Pinniped lactation strategies: Evaluation of data on maternal and offspring life history traits. Marine Mammal Science. 2004;

[196] Lea MA, Cherel Y, Guinet C, Nichols PD. Antarctic fur seals foraging in the polar frontal zone: Inter-annual shifts in diet as shown from fecal and fatty acid analyses. Marine Ecology Progress Series. 2002;245:281-297

[194] Boyd IL. Environmental and physiological factors controlling the reproductive cycles of pinnipeds. Canadian Journal of Fisheries and Aquatic Sciences. 1991;69:1135-1148

Milk consumption and growth efficiency in Antarctic fur seal

516-526

20(1):86-114

lactation on the composition of the milk. Canadian Journal of Zoology. 1970;48:

[186] El-Sayiad GA, Habeeb AAM, El-Maghawry AM. A note on the effects of breed, stage of lactation and pregnancy status on milk composition of rabbits. Animal Production. 1994;58(1):153-157

[187] Tsiplakou E, Mountzouris KC, Zervas G. The effect of breed, stage of lactation and parity on sheep milk fat CLA content under the same feeding practices. Livestock Science. 2006,

[188] Jacobsen KL, DePeters EJ, Rogers QR, Taylor SJ. Influences of stage of lactation, teat position and sequential milk sampling on the composition of domestic cat milk (Felis catus). Journal of Animal Physiology and Animal Nutrition. 2004;88(1-2):46-58

[189] Kovacs KM, Lavigne DM. Maternal investment and neonatal growth in phocid seals. The Journal of Animal

Ecology. 1986;55:1035-1051

1(3):43-58

37

Press; 1986. pp. 79-101

[190] Ponce de León A. Lactancia y composición cuantitativa de la leche del lobo fino sudamericano Arctocephalus australis (Zimmermann, 1783).

Industria Lobera y Pesquera del Estado, Montevideo, Uruguay. Annales. 1984;

[191] Costa DP, Gentry RL. Free-ranging energetics of northern fur seal. In: Gentry RL, Kooyman GL, editors. Fur Seals: Maternal Strategies on Land and at Sea. Princeton: Princeton University

[192] Arnould JPY. Lactation and the cost of pup rearing in Antarctic fur seals.

2006;105(1-3):162-167

148-160

629-633

[178] Hood WR, Ono KA. Variation in maternal attendance patterns and pup behavior in a declining population of Steller Sea lions (Eumetopias jubatus). Canadian Journal of Zoology. 1997; 75(8):1241-1246

[179] Gentry RL, Holt JR. Attendance behavior of northern fur seals. In: Gentry RL, Kooyman GL, editors. Fur Seals: Maternal Strategies on Land and at Sea. Princeton: Princeton University Press; 1986. pp. 41-60

[180] Gales NJ, Mattlin RH. Summer diving behaviour of lactating New Zealand Sea lions, Phocarctos hookeri. Canadian Journal of Zoology. 1997; 75(10):1695-1706

[181] Chilvers BL, Wilkinson IS, Duignan PJ, Gemmell NJ. Summer foraging areas for lactating New Zealand Sea lions Phocarctos hookeri. Marine Ecology Progress Series. 2005;304: 235-247

[182] Chilvers BL, Wilkinson IS, Duignan PJ, Gemmell NJ. Diving to extremes: Are New Zealand Sea lions (Phocarctos hookeri) pushing their limits in a marginal habitat. Journal of Zoology (London). 2006;269:233-241

[183] Walker GE, Ling JK. Australian sea lion Neophoca cinerea. In: Ridway SH, Harrison RJ, editors. Handbook of Marine Mammals. London: Academic Press; 1981. pp. 99-118

[184] West KL, Oftedal OT, Carpenter JR, Krames BJ, Campbell M, Sweeney JC. Effect of lactation stage and concurrent pregnancy on milk composition in the bottlenose dolphin. Lactation Strategies and Milk Composition in Pinnipeds DOI: http://dx.doi.org/10.5772/intechopen.85386

Journal of Zoology. 2007;273(2): 148-160

fluctuations and migratory influences. Journal of Zoology. 1996;238(3):459-482 [177] Antonelis GA, Stewart BS,

of female northern fur seals

lions Zalophus californianus.

68(1):150-158

Lactation in Farm Animals - Biology, Physiological Basis, Nutritional Requirements…

75(8):1241-1246

Press; 1986. pp. 41-60

75(10):1695-1706

235-247

Perryman WF. Foraging characteristics

Callorhinus ursinus and California Sea

Canadian Journal of Zoology. 1990;

[178] Hood WR, Ono KA. Variation in maternal attendance patterns and pup behavior in a declining population of Steller Sea lions (Eumetopias jubatus). Canadian Journal of Zoology. 1997;

[179] Gentry RL, Holt JR. Attendance behavior of northern fur seals. In: Gentry RL, Kooyman GL, editors. Fur Seals: Maternal Strategies on Land and at Sea. Princeton: Princeton University

[180] Gales NJ, Mattlin RH. Summer diving behaviour of lactating New Zealand Sea lions, Phocarctos hookeri. Canadian Journal of Zoology. 1997;

[181] Chilvers BL, Wilkinson IS, Duignan PJ, Gemmell NJ. Summer foraging areas for lactating New Zealand Sea lions Phocarctos hookeri. Marine Ecology Progress Series. 2005;304:

[182] Chilvers BL, Wilkinson IS, Duignan PJ, Gemmell NJ. Diving to extremes: Are New Zealand Sea lions (Phocarctos hookeri) pushing their limits in a marginal habitat. Journal of Zoology

(London). 2006;269:233-241

Press; 1981. pp. 99-118

[183] Walker GE, Ling JK. Australian sea lion Neophoca cinerea. In: Ridway SH, Harrison RJ, editors. Handbook of Marine Mammals. London: Academic

[184] West KL, Oftedal OT, Carpenter JR, Krames BJ, Campbell M, Sweeney JC. Effect of lactation stage and concurrent pregnancy on milk

composition in the bottlenose dolphin.

crabeater seals (Lobodon carcinophagus) along the Antarctic peninsula. Canadian

composition of elephant seals (Mirounga leonina): Absolute measurements and estimates from bone dimensions. Journal of Zoology. 1972;167:265-276

[170] Stephens DW, Krebs JR. Foraging Theory. Princeton: Princeton University

[171] Costa DP. Reproductive and foraging energetics of high latitude penguins, albatrosses and pinnipeds: Implications for life history patterns. American Zoologist. 1991;31:111-130

[172] Staniland IJ, Boyd IL, Reid K. An energy-distance trade-off in a centralplace forager, the Antarctic fur seal (Arctocephalus gazella). Marine Biology.

[173] Peaker M, Wilde JC. Milk secretion:

Physiological Sciences. 1987;2:124-126

[174] Knight CH, Peaker M, Wilde JC. Local control of mammary development and function. Reviews of Reproduction.

[175] Trillmich F. Attendance behavior of galapagos sea lions. In: L R G, L G K, editors. Fur Seals: Maternal Strategies on Land and at Sea. Princeton: Princeton University Press; 1986. pp. 196-208

[176] Figueroa-Carranza A. Early

Guadalupe fur seal females

lactation and attendance behavior of the

(Arctocephalus townsendi) [MSc thesis]. Santa Cruz: University of California;

2007;152(2):233-241

1998;3:104-112

1994

36

Autocrine control. News in

[168] Bengston JL, Siniff DB. Reproductive aspects of female

Journal of Fisheries and Aquatic

[169] Bryden MM. Body size and

Sciences. 1981;59:92-102

Press; 1986

[185] Cook HW, Pearson AM, Simmons NM, Baker BE. Dall sheep (Ovis dalli dalli) milk. I. Effects of stage of lactation on the composition of the milk. Canadian Journal of Zoology. 1970;48: 629-633

[186] El-Sayiad GA, Habeeb AAM, El-Maghawry AM. A note on the effects of breed, stage of lactation and pregnancy status on milk composition of rabbits. Animal Production. 1994;58(1):153-157

[187] Tsiplakou E, Mountzouris KC, Zervas G. The effect of breed, stage of lactation and parity on sheep milk fat CLA content under the same feeding practices. Livestock Science. 2006, 2006;105(1-3):162-167

[188] Jacobsen KL, DePeters EJ, Rogers QR, Taylor SJ. Influences of stage of lactation, teat position and sequential milk sampling on the composition of domestic cat milk (Felis catus). Journal of Animal Physiology and Animal Nutrition. 2004;88(1-2):46-58

[189] Kovacs KM, Lavigne DM. Maternal investment and neonatal growth in phocid seals. The Journal of Animal Ecology. 1986;55:1035-1051

[190] Ponce de León A. Lactancia y composición cuantitativa de la leche del lobo fino sudamericano Arctocephalus australis (Zimmermann, 1783). Industria Lobera y Pesquera del Estado, Montevideo, Uruguay. Annales. 1984; 1(3):43-58

[191] Costa DP, Gentry RL. Free-ranging energetics of northern fur seal. In: Gentry RL, Kooyman GL, editors. Fur Seals: Maternal Strategies on Land and at Sea. Princeton: Princeton University Press; 1986. pp. 79-101

[192] Arnould JPY. Lactation and the cost of pup rearing in Antarctic fur seals.

Marine Mammal Science. 1997;13(3): 516-526

[193] Arnould JPY, Boyd IL, Socha DG. Milk consumption and growth efficiency in Antarctic fur seal (Arctocephalus gazella) pups. Canadian Journal of Zoology. 1996;74(2):254-266

[194] Boyd IL. Environmental and physiological factors controlling the reproductive cycles of pinnipeds. Canadian Journal of Fisheries and Aquatic Sciences. 1991;69:1135-1148

[195] Schulz TM, Bowen WD. Pinniped lactation strategies: Evaluation of data on maternal and offspring life history traits. Marine Mammal Science. 2004; 20(1):86-114

[196] Lea MA, Cherel Y, Guinet C, Nichols PD. Antarctic fur seals foraging in the polar frontal zone: Inter-annual shifts in diet as shown from fecal and fatty acid analyses. Marine Ecology Progress Series. 2002;245:281-297

**39**

**Chapter 2**

**Abstract**

**1. Introduction**

*and Wiem Chouchene*

Lactation Performance of Small

*Mohamed Chniter, Cyrine Darej, Imen Belhadj Slimen* 

potentialities of the main breeds of goats and sheep raised in Maghreb.

the production chain and the specific environment and breed [1].

Nowadays, dairy foods represent one of the most dietary dense food, being considerable sources of numerous nutrients, mainly calcium, riboflavin, phosphorus, protein, magnesium, vitamin B12, niacin equivalents, vitamin B6, and when fortified, vitamins A and D. Milk and dairy products are also one of the major sources of nutritional calcium which is essential both in bone development, and the

In the Mediterranean zones, dairy sheep and goats rural managements diverge from pastoral (showed irregular milk production, dual-purpose breeds, insignificant feed supplementation, transhumance, hand milking, absence of farm facilities, farm-made cheese) to intensive management (continuous milk production, enhanced local breeds, valorization of forage crops, feed supplementation, machine milking and farm facilities, profitable cheeses) according to the profitable impact of

The Mediterranean small ruminant dairy sector is original and very diverse. More than 46% of the dairy ewes in the world originates from the Mediterranean region. The major countries, in terms of the flock of dairy ewes and goats, are Greece, Italy, Spain, France and Turkey in Europe, and Algeria, Tunisia, Egypt and Libya in North Africa [2]. In North Africa, where there is no strong dairy tradition,

**Keywords:** sheep—goats—milk, Maghreb areas

maintenance of healthy teeth [73].

Ruminants in the Maghreb Region

Maghreb areas are characterized by rainfall seasonality and scarcity resulting in a low fodder potential. In these arid and semiarid regions areas, small ruminant production is the main source of income of farmers living where sheep (*Ovis aries*) and goats (*Capra hircus*) are generally confronted with severe nutritional deficits during feed scarcity period which exacerbate disease and health troubles and consequently low performances. Interestingly and despite the importance of the milk performance to the dairy industry, very few works studied the potentialities of the mammary gland through the lactation period both in sheep and goats elevated in the Maghreb areas. Nevertheless, understanding the different mammary gland patterns throughout lactation is essential to improve dairy production and to reduce poverty and vulnerability in rural farming systems in these developing areas. The main objective of this review is to analyse the lactate processes as well as to underline the mammary gland morphological patterns, health and physiology traits and to evaluate milk

#### **Chapter 2**

## Lactation Performance of Small Ruminants in the Maghreb Region

*Mohamed Chniter, Cyrine Darej, Imen Belhadj Slimen and Wiem Chouchene*

#### **Abstract**

Maghreb areas are characterized by rainfall seasonality and scarcity resulting in a low fodder potential. In these arid and semiarid regions areas, small ruminant production is the main source of income of farmers living where sheep (*Ovis aries*) and goats (*Capra hircus*) are generally confronted with severe nutritional deficits during feed scarcity period which exacerbate disease and health troubles and consequently low performances. Interestingly and despite the importance of the milk performance to the dairy industry, very few works studied the potentialities of the mammary gland through the lactation period both in sheep and goats elevated in the Maghreb areas. Nevertheless, understanding the different mammary gland patterns throughout lactation is essential to improve dairy production and to reduce poverty and vulnerability in rural farming systems in these developing areas. The main objective of this review is to analyse the lactate processes as well as to underline the mammary gland morphological patterns, health and physiology traits and to evaluate milk potentialities of the main breeds of goats and sheep raised in Maghreb.

**Keywords:** sheep—goats—milk, Maghreb areas

#### **1. Introduction**

Nowadays, dairy foods represent one of the most dietary dense food, being considerable sources of numerous nutrients, mainly calcium, riboflavin, phosphorus, protein, magnesium, vitamin B12, niacin equivalents, vitamin B6, and when fortified, vitamins A and D. Milk and dairy products are also one of the major sources of nutritional calcium which is essential both in bone development, and the maintenance of healthy teeth [73].

In the Mediterranean zones, dairy sheep and goats rural managements diverge from pastoral (showed irregular milk production, dual-purpose breeds, insignificant feed supplementation, transhumance, hand milking, absence of farm facilities, farm-made cheese) to intensive management (continuous milk production, enhanced local breeds, valorization of forage crops, feed supplementation, machine milking and farm facilities, profitable cheeses) according to the profitable impact of the production chain and the specific environment and breed [1].

The Mediterranean small ruminant dairy sector is original and very diverse. More than 46% of the dairy ewes in the world originates from the Mediterranean region. The major countries, in terms of the flock of dairy ewes and goats, are Greece, Italy, Spain, France and Turkey in Europe, and Algeria, Tunisia, Egypt and Libya in North Africa [2]. In North Africa, where there is no strong dairy tradition,

ewe and above all goat milk is used mainly for family consumption likes as milk or white fresh cheese the 'Jben Arbi'. It has been considered that milk has a symbolic value of life and fertility in the Maghreb regions, as it is often used, with dates, in ceremonies to welcome guests according to the Berber and the Arabic traditions [3]. In these regions, small ruminant and camel constitute the most valuable activities in arid areas based on their resistance to dry or hot conditions. This resistance to harsh conditions evaluated in terms on adaptive traits or rusticity, is based on different abilities: mobility, physiology, feeding pattern, etc. Furthermore, sheep and goats need low investment resources and fast rate of reproduction covers short term expenditures.

In such developing countries of Maghreb, dairy production is an essential tool to overcome social and economic issues like as poverty and human malnutrition [4]. However, despite its potential contribution to sustainable economic growth and poverty drop, dairy sheep and goats sector has received restricted attention from Maghreb Nations in recent decades. Furthermore, little is known about dairy sheep and goats reared in Maghreb Nations [28, 52] and a better knowledge of these genetic resources can help promote their conservation and efficiency benefits. Therefore it is critical to understand the modifications associated with lactation in the mammary gland in order to develop strategies to improve milk yield or reduce the constraints that decrease milk production and milk quality in dairy Maghreb sheep and goats. Considering the current significance of sheep and goat milk production, this review draws a study to analyse the lactate processes as well as to underline the mammary gland morphological patterns and physiology traits and to evaluate milk potentialities of the main breeds of sheep and goats raised in the Maghreb areas. Overall, such data will be important in supporting further studies aimed at improving lactation potentialities, among other factors, with benefits for this emerging dairy sector for both the industry and the consumer.

#### **2. Overview on Maghreb areas**

Located in the Northern fringes of Africa, the Maghreb areas (Lybia, Tunisia, Algeria and Morocco) have a long tradition with dairy products' consumption. The Maghreb countries are distinguished by their typical Mediterranean climate; a long summer (May to September) with an intense drought and excessive heat and often an irregular rainfall from autumn to spring [5].

Another trait which distinguishes the Maghreb climate, the marine effect which reduces the amplitude of temperatures in zones near to the landfall: the Mediterranean in Morocco, Algeria and Tunisia and the Atlantic Ocean in Morocco. The normal annual precipitation is less than 300 mm in wide regions of the Maghreb countries, engendering arid to semi-arid climates [6].

Therefore water scarcity constitutes the main limiting factor to agriculture. Hence, the agricultural output in the Maghreb remains largely related to the level of annual rainfall in rain fed areas [9], with no opportunities of irrigation. The hydrological water stress index is respectively 29, 11 and 3 in Algeria, Morocco and Tunisia. Such index implies that at the regional level, Algeria and Tunisia face the highest level of water stress, while in Morocco water is less scarce [7]. This situation will certainly widen with the expected demographic growth and climate change, and consequently, have negative repercussions [8].

The photoperiod is another significant factor that affects sheep and goats productivity especially in breeds that originate from geographical areas at high latitudes. Thus, appropriate supervisory policies must be developed to allow milk production out of season in small ruminants [1].

**41**

*Lactation Performance of Small Ruminants in the Maghreb Region*

**3. Review on lactogenesis and mammary gland traits**

Lactogenesis may be defined as the beginning of milk secretion [12]. This physiological mechanism can group two stages. The first stage occurs during pregnancy when the gland is adequately differentiated to produce little amounts of specific milk components like lactose and caseins [13]. The second stage can be defined as the start of copious milk liberation depended to parturition. Nutrition during pregnancy is the most factor that affects both colostrum yield and composition [14]. When small ruminants are kept under poor grazing conditions, there is a general mobilisation of their body reserves during the last 6 weeks of gestation owing to

The structure and the function of the mammary gland are coordinated by the neuroendocrine control from the development of the gland via the milk ejection. The main role of the endocrine mechanism is to synchronise mammary function and development with the reproductive stage, while the main role of the nervous mechanism is to stimulate the process of milk removal. These two mechanisms are joined in the hypothalamic-pituitary axis, and manage the entire process of milk production through the release of several crops (lactose, prolactin, oxytocin, growth hormone, etc.) as well as the coordination of other hormone-releasing organs, i.e., mammary gland, placenta, ovaries [17]. The proliferation of mammary tissue may be activated by the prolactin secreted in response to the gland stimulus. However, other factors of the normal mammogenic complex are either entirely absent during lactation (e.g., placental lactogen) or just present in small amounts or

Suppression of prolactin secretion in goats and sheep [19, 20] had only partially in sheep lactation. This hormone is at least as important as growth factor in main-

When it was administrated to pre-pubertal young ewe, the bromocriptine (prolactin inhibitor) had no effect on the mammary development [22]. However, a treatment with progesterone in post-pubertal ewes suppressed the epithelial

The completion of tubuloalveolar development in ewes ultimately requires oestrogen and progesterone in the presence of endogenous prolactin [24]. One of the classical roles assigned to oxytocin is milk ejection from the mammary gland. Although it is mainly associated with milk ejection, treatment with exogenous oxytocin was associated with increased milk production in sheep [25]. The major amount of the milk is accumulated in voluminous cisterns of the goat gland thus it can be remote through by suction applied to the nipples. Hence, a milk discharge reflex is not necessary for the nourishing of the young, though it could help the process [25, 26]. In fact it is possible to identify goats with very high milk yield and either strong milk flow rate that have no appreciable increases in plasma oxytocin concentrations during milking [27]. Perhaps this finding is indicative of a lower

In small ruminant mammary gland, the glandular parenchyma is responsible for milk production and is constituted by tubule-alveolar glands relative to its anatomical organization; it has two main components, (1) the parenchyma which includes the epithelial and myoepithelial cells, (2) the stroma involving the non-cellular components, as collagen and elastin, smooth muscle cells and vessels and the ductal system [29]. However, it is important to note that anatomy and histology of the mammary gland are changed during the lactation stage, mostly led by the neuroendocrine mechanism. There are three stages of mammary biology characterising the pregnancy/lactation periods: proliferation, secretion and involution. While the most proliferation happens throughout gestation and most of the involution occurs

*DOI: http://dx.doi.org/10.5772/intechopen.85778*

rapid fetal growth and colostrum yield [15, 16].

at specific moments (e.g., oestrogen) [18].

dependency on oxytocin for milk removal in goats.

taining goat milk yield [21].

proliferation [23].

*Lactation in Farm Animals - Biology, Physiological Basis, Nutritional Requirements…*

ewe and above all goat milk is used mainly for family consumption likes as milk or white fresh cheese the 'Jben Arbi'. It has been considered that milk has a symbolic value of life and fertility in the Maghreb regions, as it is often used, with dates, in ceremonies to welcome guests according to the Berber and the Arabic traditions [3]. In these regions, small ruminant and camel constitute the most valuable activities in arid areas based on their resistance to dry or hot conditions. This resistance to harsh conditions evaluated in terms on adaptive traits or rusticity, is based on different abilities: mobility, physiology, feeding pattern, etc. Furthermore, sheep and goats need low investment resources and fast rate of reproduction covers short term

In such developing countries of Maghreb, dairy production is an essential tool to overcome social and economic issues like as poverty and human malnutrition [4]. However, despite its potential contribution to sustainable economic growth and poverty drop, dairy sheep and goats sector has received restricted attention from Maghreb Nations in recent decades. Furthermore, little is known about dairy sheep and goats reared in Maghreb Nations [28, 52] and a better knowledge of these genetic resources can help promote their conservation and efficiency benefits. Therefore it is critical to understand the modifications associated with lactation in the mammary gland in order to develop strategies to improve milk yield or reduce the constraints that decrease milk production and milk quality in dairy Maghreb sheep and goats. Considering the current significance of sheep and goat milk production, this review draws a study to analyse the lactate processes as well as to underline the mammary gland morphological patterns and physiology traits and to evaluate milk potentialities of the main breeds of sheep and goats raised in the Maghreb areas. Overall, such data will be important in supporting further studies aimed at improving lactation potentialities, among other factors, with benefits for

this emerging dairy sector for both the industry and the consumer.

Located in the Northern fringes of Africa, the Maghreb areas (Lybia, Tunisia, Algeria and Morocco) have a long tradition with dairy products' consumption. The Maghreb countries are distinguished by their typical Mediterranean climate; a long summer (May to September) with an intense drought and excessive heat and often

Another trait which distinguishes the Maghreb climate, the marine effect which reduces the amplitude of temperatures in zones near to the landfall: the Mediterranean in Morocco, Algeria and Tunisia and the Atlantic Ocean in Morocco.

Therefore water scarcity constitutes the main limiting factor to agriculture. Hence, the agricultural output in the Maghreb remains largely related to the level of annual rainfall in rain fed areas [9], with no opportunities of irrigation. The hydrological water stress index is respectively 29, 11 and 3 in Algeria, Morocco and Tunisia. Such index implies that at the regional level, Algeria and Tunisia face the highest level of water stress, while in Morocco water is less scarce [7]. This situation will certainly widen with the expected demographic growth and climate change,

The photoperiod is another significant factor that affects sheep and goats productivity especially in breeds that originate from geographical areas at high latitudes. Thus, appropriate supervisory policies must be developed to allow milk

The normal annual precipitation is less than 300 mm in wide regions of the

Maghreb countries, engendering arid to semi-arid climates [6].

**2. Overview on Maghreb areas**

an irregular rainfall from autumn to spring [5].

and consequently, have negative repercussions [8].

production out of season in small ruminants [1].

**40**

expenditures.

#### **3. Review on lactogenesis and mammary gland traits**

Lactogenesis may be defined as the beginning of milk secretion [12]. This physiological mechanism can group two stages. The first stage occurs during pregnancy when the gland is adequately differentiated to produce little amounts of specific milk components like lactose and caseins [13]. The second stage can be defined as the start of copious milk liberation depended to parturition. Nutrition during pregnancy is the most factor that affects both colostrum yield and composition [14]. When small ruminants are kept under poor grazing conditions, there is a general mobilisation of their body reserves during the last 6 weeks of gestation owing to rapid fetal growth and colostrum yield [15, 16].

The structure and the function of the mammary gland are coordinated by the neuroendocrine control from the development of the gland via the milk ejection. The main role of the endocrine mechanism is to synchronise mammary function and development with the reproductive stage, while the main role of the nervous mechanism is to stimulate the process of milk removal. These two mechanisms are joined in the hypothalamic-pituitary axis, and manage the entire process of milk production through the release of several crops (lactose, prolactin, oxytocin, growth hormone, etc.) as well as the coordination of other hormone-releasing organs, i.e., mammary gland, placenta, ovaries [17]. The proliferation of mammary tissue may be activated by the prolactin secreted in response to the gland stimulus.

However, other factors of the normal mammogenic complex are either entirely absent during lactation (e.g., placental lactogen) or just present in small amounts or at specific moments (e.g., oestrogen) [18].

Suppression of prolactin secretion in goats and sheep [19, 20] had only partially in sheep lactation. This hormone is at least as important as growth factor in maintaining goat milk yield [21].

When it was administrated to pre-pubertal young ewe, the bromocriptine (prolactin inhibitor) had no effect on the mammary development [22]. However, a treatment with progesterone in post-pubertal ewes suppressed the epithelial proliferation [23].

The completion of tubuloalveolar development in ewes ultimately requires oestrogen and progesterone in the presence of endogenous prolactin [24]. One of the classical roles assigned to oxytocin is milk ejection from the mammary gland. Although it is mainly associated with milk ejection, treatment with exogenous oxytocin was associated with increased milk production in sheep [25]. The major amount of the milk is accumulated in voluminous cisterns of the goat gland thus it can be remote through by suction applied to the nipples. Hence, a milk discharge reflex is not necessary for the nourishing of the young, though it could help the process [25, 26]. In fact it is possible to identify goats with very high milk yield and either strong milk flow rate that have no appreciable increases in plasma oxytocin concentrations during milking [27]. Perhaps this finding is indicative of a lower dependency on oxytocin for milk removal in goats.

In small ruminant mammary gland, the glandular parenchyma is responsible for milk production and is constituted by tubule-alveolar glands relative to its anatomical organization; it has two main components, (1) the parenchyma which includes the epithelial and myoepithelial cells, (2) the stroma involving the non-cellular components, as collagen and elastin, smooth muscle cells and vessels and the ductal system [29]. However, it is important to note that anatomy and histology of the mammary gland are changed during the lactation stage, mostly led by the neuroendocrine mechanism. There are three stages of mammary biology characterising the pregnancy/lactation periods: proliferation, secretion and involution. While the most proliferation happens throughout gestation and most of the involution occurs

after lactation has finished, such processes coincide: proliferation of secretory tissue persists during early lactation and involution initiates during late lactation, simultaneously with milk secretion [30].

Concerning the lactation period, it differs between small ruminant species. In sheep lactation, it lasts for 5 months with a peak between the weeks 3 and 4 [23, 31]. In contrast, the lactation period in goats lasts for 10 months with a peak between weeks 5 and 10 [32]. These values are highly dependent on breed and nutritional status, among other factors [33].

By studying the mammary gland volume changes in goat breeds (Toggenburg, Nubian, Saanen and French Alpine) during various physiological stages [34, 35], no differences were detected in udder weights during pregnancy until day 120, when values started to increase significantly. The majority of udder growth occurred between the last 30 days of pregnancy and the first 10 days of lactation.

During gestation and lactation, an alteration of mammary gland tissue composition occurs, as well as for the first 15 days of gestation, where parenchyma fatty tissue proportion decreases and fluid-rich tissue increases [35]. Such alterations in parenchyma composition can be directly related to the increment of milk secretion and fluid accumulation in the gland [35]. Thereafter, mammary gland composition remains constant throughout late gestation and the entire lactation period. As the majority of udder growth occurs during early lactation, a reduction of mammary gland volume was detected during mid-lactation [37]. Reduction of the udder volume during the stage of lactation was reported as correlated both to parities and the mammary gland volume at the onset of lactation [37]. For example, goats with twins had more voluminous udder (+40%) than those with simples [38].

#### **4. Review on the milk potentialities of goats and sheep raised in Maghreb and Mediterranean areas**

Sheep and goats are mainly elevated for meat production in many regions of the Maghreb areas because of the harsh environments prevailing. The most of breeds have not been selected for milk yield, at the exception of the Sicilo-Sarde, where its nucleus was in Tunisia [10]. Thus, the official statistics reveal that the integrated dairy chains rely mainly on cattle milk, given that milk from non-cattle species (small ruminants and camel) represents respectively 21.3, 5.1 and 3.7% of the overall output in Algeria, Morocco and Tunisia [11] and its industrial processing remains rather weak.

After an increase by 18.7% (1997–2007), the goat population reached more than 1.5 million heads in Tunisia [66]. Such growth has been followed by the increase of production. Almost 60% of the Tunisian goats are located in the centre and in the south, reared in semi-intensive oasis systems, in small herds [70, 71]. Noting that the native goat from Tunisia is named Arbi to distinguish it from imported breeds, and it is well adapted to the natural environment of country [67]. Meat remains the major production of Arbi goats from Tunisia but also milk is produced only for home consumption. Under semi-arid conditions in the South, milk potential of the Arbi goat ranged from 1.14 to 0.69 kg/goat/day in the first 6 weeks of lactation, for females suckling singles, while those suckling twins produced 0.86–1.64 kg/goat/ day [36]. Similarly, milk production ranged from 1.2 to 0.75 kg/goat/day [74] in the north where goats are reared in extensive mixed farming systems [69], together with sheep and cows. Genetic improvement schemes and biodiversity conservation strategies are currently studied in Tunisia for the native goat [68]. In some cases, the genetic capacities represent a serious restriction to improve goat production, especially for milk [72]. Failures in livestock improvement programs (national and international projects) did happen and animal productivity has remained poor.

**43**

*Lactation Performance of Small Ruminants in the Maghreb Region*

cost and maintain such peak yield for as long as possible [78, 79].

When considering breed sheep, the only African dairy one is the Sicilo-Sarde as its milk is mostly used for cheese manufacturing. The population of Sicilo-Sarde is estimated at approximately 20,000 animals concentrated in northern Tunisia [62]. This breed was originated in the early twentieth century by crossing the Sarda and the Comisana dairy breeds, from Sardinia and Sicily (Italy), respectively, to produce

The lactation curves have wide possibilities of applications, especially in genetic evaluation [75], ratio formulation and economic evaluation of different breeding practices [76, 77]. The prediction of yield peak is indispensable for the arrangement of feed orientation permitting and to cover the requirement of animal, reduce the

A recent study taken in the Sicilo-Sarde breed [80] showed an average of daily milk production of 0.46 L with a high variation between 0.10 and 2.40 L and a milk period of 132.8 days. This study shows also a similar milking-only length (139 ± 47 days) and suckling length (104 ± 22 days) to previous reports [81]. Sicilo-Sarde ewes have a low production performances comparatively to Lacaune breed (on average 290 L of milk during 165 days) [82] and Sarda breed (on average 203 L and 162 days for milk yield and milking period) [82]. Such difference can be explained by a random crossing with other breeds which could threaten the genetic integrity and partly explains the low milking performances of Sicilo-

Rural management farm of the Tunisian Sicilo-Sarde sheep marked a long suckling interval (3–4 months) and long lambing period (August to October) [63]. Therefore, the weaning practice applied depends on the selling price of milk. If prices are high, early weaning is practiced; if not milk is reserved only for lamb suckling. Several attempts have been undertaken during recent years in order to rehabilitate the dairy sheep sector in Tunisia [62], as well as to increase the combined member's herd size from 10,000 to 30,000 Female Units and to improve the milk yield/ewe/year from 90 to 150 L [64]. Several considerations were taken to encourage the association of breeders, control the performance and to enhance the pasture productivity throughout many programs managed by the OEP (Office of Livestock and Pastures) like as via the training and information days [65].

Udder volume evaluated for Sicilo-Sarde [52] is similar to that of Manchega dairy ewes, but smaller than that of Lacaune and Istrian dairy crossbreed ewes [50, 56]. Positive correlations were observed between estimated daily milk yield and both udder depth and udder volume in Sicilo-Sarde [45, 52]. Cisternal area also positively correlated with total milk yield, indicating that ultrasonography could be used for predicting milk yield in Sicilo-Sarde ewes. Milking lag time and total milking time reported in Sicilo-Sarde [52] were shorter than those reported in Manchega dairy ewes [61], probably due to differences between breeds in milk yield. Similarly, positive correlations were also observed between daily milk yield and both udder depth and udder volume [45, 52]. Sicilo-Sarde ewes showed adequate udder morphology for machine milking. The percentage of cisternal milk in this breed (54%) is similar to values reported in Manchega ewes [53, 54] and East Friesian crossbred dairy ewes [60], but lower than in Lacaune (74–77%) [53, 54] and Sarda ewes (82%) [58]. A medium correlation (r = 0.69) was reported between cisternal area and cisternal milk at 8 h after milking in Sicilo-Sarde, as a consequence of a multilocular structure, being lower than correlations reported in Manchega ewes [53, 54], dairy goats [57], and dairy cows [59]. According to previous observations on Mediterranean dairy sheep [46], Sicilo-Sarde dairy ewes are characterized by medium size udders and favourable teat position. This breed showed adequate udder morphology for machine milking [52]. Sicilo-Sarde dairy ewes are also characterized by favourable

teat position [46, 52], and can be grouped as medium-cisterned ewes [52].

*DOI: http://dx.doi.org/10.5772/intechopen.85778*

sheep cheese for the Italian community.

Sarde breed [36].

*Lactation in Farm Animals - Biology, Physiological Basis, Nutritional Requirements…*

between the last 30 days of pregnancy and the first 10 days of lactation.

twins had more voluminous udder (+40%) than those with simples [38].

**4. Review on the milk potentialities of goats and sheep raised in** 

Morocco and Tunisia [11] and its industrial processing remains rather weak.

Sheep and goats are mainly elevated for meat production in many regions of the Maghreb areas because of the harsh environments prevailing. The most of breeds have not been selected for milk yield, at the exception of the Sicilo-Sarde, where its nucleus was in Tunisia [10]. Thus, the official statistics reveal that the integrated dairy chains rely mainly on cattle milk, given that milk from non-cattle species (small ruminants and camel) represents respectively 21.3, 5.1 and 3.7% of the overall output in Algeria,

After an increase by 18.7% (1997–2007), the goat population reached more than 1.5 million heads in Tunisia [66]. Such growth has been followed by the increase of production. Almost 60% of the Tunisian goats are located in the centre and in the south, reared in semi-intensive oasis systems, in small herds [70, 71]. Noting that the native goat from Tunisia is named Arbi to distinguish it from imported breeds, and it is well adapted to the natural environment of country [67]. Meat remains the major production of Arbi goats from Tunisia but also milk is produced only for home consumption. Under semi-arid conditions in the South, milk potential of the Arbi goat ranged from 1.14 to 0.69 kg/goat/day in the first 6 weeks of lactation, for females suckling singles, while those suckling twins produced 0.86–1.64 kg/goat/ day [36]. Similarly, milk production ranged from 1.2 to 0.75 kg/goat/day [74] in the north where goats are reared in extensive mixed farming systems [69], together with sheep and cows. Genetic improvement schemes and biodiversity conservation strategies are currently studied in Tunisia for the native goat [68]. In some cases, the genetic capacities represent a serious restriction to improve goat production, especially for milk [72]. Failures in livestock improvement programs (national and international projects) did happen and animal productivity has remained poor.

**Maghreb and Mediterranean areas**

neously with milk secretion [30].

status, among other factors [33].

after lactation has finished, such processes coincide: proliferation of secretory tissue persists during early lactation and involution initiates during late lactation, simulta-

Concerning the lactation period, it differs between small ruminant species. In sheep lactation, it lasts for 5 months with a peak between the weeks 3 and 4 [23, 31]. In contrast, the lactation period in goats lasts for 10 months with a peak between weeks 5 and 10 [32]. These values are highly dependent on breed and nutritional

By studying the mammary gland volume changes in goat breeds (Toggenburg, Nubian, Saanen and French Alpine) during various physiological stages [34, 35], no differences were detected in udder weights during pregnancy until day 120, when values started to increase significantly. The majority of udder growth occurred

During gestation and lactation, an alteration of mammary gland tissue composition occurs, as well as for the first 15 days of gestation, where parenchyma fatty tissue proportion decreases and fluid-rich tissue increases [35]. Such alterations in parenchyma composition can be directly related to the increment of milk secretion and fluid accumulation in the gland [35]. Thereafter, mammary gland composition remains constant throughout late gestation and the entire lactation period. As the majority of udder growth occurs during early lactation, a reduction of mammary gland volume was detected during mid-lactation [37]. Reduction of the udder volume during the stage of lactation was reported as correlated both to parities and the mammary gland volume at the onset of lactation [37]. For example, goats with

**42**

When considering breed sheep, the only African dairy one is the Sicilo-Sarde as its milk is mostly used for cheese manufacturing. The population of Sicilo-Sarde is estimated at approximately 20,000 animals concentrated in northern Tunisia [62]. This breed was originated in the early twentieth century by crossing the Sarda and the Comisana dairy breeds, from Sardinia and Sicily (Italy), respectively, to produce sheep cheese for the Italian community.

The lactation curves have wide possibilities of applications, especially in genetic evaluation [75], ratio formulation and economic evaluation of different breeding practices [76, 77]. The prediction of yield peak is indispensable for the arrangement of feed orientation permitting and to cover the requirement of animal, reduce the cost and maintain such peak yield for as long as possible [78, 79].

A recent study taken in the Sicilo-Sarde breed [80] showed an average of daily milk production of 0.46 L with a high variation between 0.10 and 2.40 L and a milk period of 132.8 days. This study shows also a similar milking-only length (139 ± 47 days) and suckling length (104 ± 22 days) to previous reports [81]. Sicilo-Sarde ewes have a low production performances comparatively to Lacaune breed (on average 290 L of milk during 165 days) [82] and Sarda breed (on average 203 L and 162 days for milk yield and milking period) [82]. Such difference can be explained by a random crossing with other breeds which could threaten the genetic integrity and partly explains the low milking performances of Sicilo-Sarde breed [36].

Rural management farm of the Tunisian Sicilo-Sarde sheep marked a long suckling interval (3–4 months) and long lambing period (August to October) [63]. Therefore, the weaning practice applied depends on the selling price of milk. If prices are high, early weaning is practiced; if not milk is reserved only for lamb suckling. Several attempts have been undertaken during recent years in order to rehabilitate the dairy sheep sector in Tunisia [62], as well as to increase the combined member's herd size from 10,000 to 30,000 Female Units and to improve the milk yield/ewe/year from 90 to 150 L [64]. Several considerations were taken to encourage the association of breeders, control the performance and to enhance the pasture productivity throughout many programs managed by the OEP (Office of Livestock and Pastures) like as via the training and information days [65].

Udder volume evaluated for Sicilo-Sarde [52] is similar to that of Manchega dairy ewes, but smaller than that of Lacaune and Istrian dairy crossbreed ewes [50, 56]. Positive correlations were observed between estimated daily milk yield and both udder depth and udder volume in Sicilo-Sarde [45, 52]. Cisternal area also positively correlated with total milk yield, indicating that ultrasonography could be used for predicting milk yield in Sicilo-Sarde ewes. Milking lag time and total milking time reported in Sicilo-Sarde [52] were shorter than those reported in Manchega dairy ewes [61], probably due to differences between breeds in milk yield. Similarly, positive correlations were also observed between daily milk yield and both udder depth and udder volume [45, 52]. Sicilo-Sarde ewes showed adequate udder morphology for machine milking. The percentage of cisternal milk in this breed (54%) is similar to values reported in Manchega ewes [53, 54] and East Friesian crossbred dairy ewes [60], but lower than in Lacaune (74–77%) [53, 54] and Sarda ewes (82%) [58]. A medium correlation (r = 0.69) was reported between cisternal area and cisternal milk at 8 h after milking in Sicilo-Sarde, as a consequence of a multilocular structure, being lower than correlations reported in Manchega ewes [53, 54], dairy goats [57], and dairy cows [59]. According to previous observations on Mediterranean dairy sheep [46], Sicilo-Sarde dairy ewes are characterized by medium size udders and favourable teat position. This breed showed adequate udder morphology for machine milking [52]. Sicilo-Sarde dairy ewes are also characterized by favourable teat position [46, 52], and can be grouped as medium-cisterned ewes [52].

The seasonality of milk production characterizes the major dairy sheep industry. Nevertheless, an intensive breeding system of dairy ewes has practiced in some countries of the Mediterranean basin, for examples, those in Israel and Spain, where two breeds are mainly elevated: the Assaf and Awassi [39, 40]. In such managements based on the keeping indoors of ewes during the year and an accelerated lambing rhythm is applied with several mating/insemination season. Milking practice starts from the first day of the lactation's ewe and lambs are immediately adapted to an artificial rearing unit after their birth. Such practice of milking regime is exclusive for dairy ewe. For the Assaf ewes, few conceptions occur in early spring (February and March), which is considered an "out of season" period as it commonly results in a low conception rate and few lambs being born in summer (July and August) [41, 42].

In Italy, production of ewe milk is strongly seasonal and this seasonal production system involves most of the dairy breeds. However, under certain environmental conditions, certain breeds are able to mate during different periods. A weaning drop of milk potential is generally detected in dairy breeds [43, 44] and can be explained by the partial disappearance of the stimulus produced by the lamb when suckling. The decrease of milk production after weaning varied from 30 to 40% in the Lacaune, Préalpes du Sud, and Awassi breeds [45]. Likewise, it was observed [47] that the decrease of milk production at weaning (23–35%) may be explicated by a drop of emptying frequency (20–25%) and probably by a separation of mother-kid (3–7%). Sicilo-Sarde ewes are characterized by reduced teats in comparison with Manchega, Lacaune, Istrian dairy crossbreed and Bergamasca ewes [48–50, 55]. No significant correlations exist between teat length and milk production [48, 50]. The teat diameter of Sicilo-Sarde, measured at the medium point of the teat, was smaller than values reported in French Rouge de l'Ouest ewes [51]. Teat angle exists in of Sicilo-Sarde similarly to those in Manchega and Istrian dairy crossbreed ewes [50, 56], but with great values than those observed in French Rouge de l'Ouest ewes (26.5°) [51]. Udder volume calculated for Sicilo-Sarde is similar to that of Manchega dairy ewes, but smaller than that of Lacaune and Istrian dairy crossbreed ewes [50, 56].

#### **5. Conclusions**

The productive potential of Maghreb goats and sheep has to be considered taking into account the environmental factors and other genetic and epigenetic factors which may affect milk and lipid content.

Programs reserved to smallholder units must be urgently developed, considering their intervention as the main actors in dairy farming, and this to promote the overall farm performances, to adopt an efficiency strategy of irrigation, fodder biomass yield and its conversion to animal protein (milk and meat) and orient such farms towards dairy specialized producers.

In addition, further efforts are desirable for the promotion and diversification of income sources in dairy production chains. This will have a direct result with the development of good governance to anticipate and overcome future collective challenges: transparent appreciation and remuneration of milk quality, regular negotiations between stakeholders (smallholders, collection cooperatives and milk processors). Considering the increasing price of animal feed products on the world markets, the promotion of self-sustaining milk production chains will be indispensable.

Otherwise, preserving some small ruminant breeds of Maghreb again degradation or extinction requires an urgent establishment of breeding program simultaneously with an awareness of farmers through the action of associations that should

**45**

**Author details**

Tunisia

provided the original work is properly cited.

\*Address all correspondence to: mchniter@gmail.com

*Lactation Performance of Small Ruminants in the Maghreb Region*

production system in the Maghreb areas; milk and meat.

be supported over some subsidies especially livestock feed, programming technical training for farmers, milk collectors and the creation of other industrial processing

Understanding the lactate processes as well as to underline the mammary gland morphological patterns and physiology traits as well as milk potentialities of the sheep and goats may improve dairy production efficiency and would be basis to better define selection indices for dairy sheep and goats breeds under a dual purpose

We declare that we did not have any "conflict of interest" declaration.

*DOI: http://dx.doi.org/10.5772/intechopen.85778*

units.

**Conflict of interest**

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

Mohamed Chniter\*, Cyrine Darej, Imen Belhadj Slimen and Wiem Chouchene Department of Animal Sciences, National Institute of Agronomy of Tunisia, Tunis, *Lactation Performance of Small Ruminants in the Maghreb Region DOI: http://dx.doi.org/10.5772/intechopen.85778*

be supported over some subsidies especially livestock feed, programming technical training for farmers, milk collectors and the creation of other industrial processing units.

Understanding the lactate processes as well as to underline the mammary gland morphological patterns and physiology traits as well as milk potentialities of the sheep and goats may improve dairy production efficiency and would be basis to better define selection indices for dairy sheep and goats breeds under a dual purpose production system in the Maghreb areas; milk and meat.

### **Conflict of interest**

*Lactation in Farm Animals - Biology, Physiological Basis, Nutritional Requirements…*

(July and August) [41, 42].

**5. Conclusions**

which may affect milk and lipid content.

farms towards dairy specialized producers.

The seasonality of milk production characterizes the major dairy sheep industry.

In Italy, production of ewe milk is strongly seasonal and this seasonal production system involves most of the dairy breeds. However, under certain environmental conditions, certain breeds are able to mate during different periods. A weaning drop of milk potential is generally detected in dairy breeds [43, 44] and can be explained by the partial disappearance of the stimulus produced by the lamb when suckling. The decrease of milk production after weaning varied from 30 to 40% in the Lacaune, Préalpes du Sud, and Awassi breeds [45]. Likewise, it was observed [47] that the decrease of milk production at weaning (23–35%) may be explicated by a drop of emptying frequency (20–25%) and probably by a separation of mother-kid (3–7%). Sicilo-Sarde ewes are characterized by reduced teats in comparison with Manchega, Lacaune, Istrian dairy crossbreed and Bergamasca ewes [48–50, 55]. No significant correlations exist between teat length and milk production [48, 50]. The teat diameter of Sicilo-Sarde, measured at the medium point of the teat, was smaller than values reported in French Rouge de l'Ouest ewes [51]. Teat angle exists in of Sicilo-Sarde similarly to those in Manchega and Istrian dairy crossbreed ewes [50, 56], but with great values than those observed in French Rouge de l'Ouest ewes (26.5°) [51]. Udder volume calculated for Sicilo-Sarde is similar to that of Manchega dairy ewes, but

smaller than that of Lacaune and Istrian dairy crossbreed ewes [50, 56].

The productive potential of Maghreb goats and sheep has to be considered taking into account the environmental factors and other genetic and epigenetic factors

Programs reserved to smallholder units must be urgently developed, considering their intervention as the main actors in dairy farming, and this to promote the overall farm performances, to adopt an efficiency strategy of irrigation, fodder biomass yield and its conversion to animal protein (milk and meat) and orient such

In addition, further efforts are desirable for the promotion and diversification of income sources in dairy production chains. This will have a direct result with the development of good governance to anticipate and overcome future collective challenges: transparent appreciation and remuneration of milk quality, regular negotiations between stakeholders (smallholders, collection cooperatives and milk processors). Considering the increasing price of animal feed products on the world markets, the promotion of self-sustaining milk production chains will be

Otherwise, preserving some small ruminant breeds of Maghreb again degradation or extinction requires an urgent establishment of breeding program simultaneously with an awareness of farmers through the action of associations that should

Nevertheless, an intensive breeding system of dairy ewes has practiced in some countries of the Mediterranean basin, for examples, those in Israel and Spain, where two breeds are mainly elevated: the Assaf and Awassi [39, 40]. In such managements based on the keeping indoors of ewes during the year and an accelerated lambing rhythm is applied with several mating/insemination season. Milking practice starts from the first day of the lactation's ewe and lambs are immediately adapted to an artificial rearing unit after their birth. Such practice of milking regime is exclusive for dairy ewe. For the Assaf ewes, few conceptions occur in early spring (February and March), which is considered an "out of season" period as it commonly results in a low conception rate and few lambs being born in summer

**44**

indispensable.

We declare that we did not have any "conflict of interest" declaration.

#### **Author details**

Mohamed Chniter\*, Cyrine Darej, Imen Belhadj Slimen and Wiem Chouchene Department of Animal Sciences, National Institute of Agronomy of Tunisia, Tunis, Tunisia

\*Address all correspondence to: mchniter@gmail.com

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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9783540096801

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agee.2008.01.011

[1] Todaroa M, Dattenab M, Acciaiolic A, Bonannoa A, Brunid G, Caropresee M, et al. A seasonal sheep and goat milk production in the Mediterranean area: Physiological and technical insights. Small Ruminant Research.

[2] FAOSTAT. 2013. Available from: http://faostat3.fao.org/home/index.html

[Accessed: 22-Auguest-2013]

10.1007/s10298-008-0296-0

Science. 2010;**130**:95-109

9780444521705

[3] Benchelah AC, Maka A. The nutritional value of dates.

Phytothérapie. 2008;**6**:117-121. DOI:

[4] McDermott JJ, Staal SJ, Freeman HA, Herrero M, Van De Steeg JA. Sustaining intensification of smallholder livestock systems in the tropics. Livestock

[5] Lionello P, Malanotte P, Boscolo R, editors. Mediterranean Climate Variability. 1st ed. Amsterdam:

Elsevier; 2006. 438 p. Hardcover. ISBN:

[6] Patricola C, Cook K. Northern African climate at the end of the twenty first century: An integrated application of regional and global climate models. Climate Dynamics. 2010;**35**:193-212. DOI: 10.1007/s00382-009-0623-7

[7] World Resources Institute. World Resources: Roots of Resilience— Growing theWealth of the Poor. Washington. DC: WRI; 2008

[8] Rijsberman FR. Water scarcity: Fact or fiction? Agricultural Water Management. 2006;**80**:5-22. DOI: 10.1016/j.agwat.2005.07.001

[9] Thomas RJ. Opportunities to reduce the vulnerability of dryland farmers in central and West Asia and North Africa to climate change. Agriculture,

Ecosystems & Environment.

2015;**126**:59-66

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*Lactation Performance of Small Ruminants in the Maghreb Region*

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Animal Science. 2005;**35**:238-243

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*Lactation in Farm Animals - Biology, Physiological Basis, Nutritional Requirements…*

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Lands (ACSAD); 1990

www.faostat.fao.org

2006. pp. 1307-1311

2007;**10**:2314-2319

2008;**79**:435-438

[70] Gaddour A, Najari S, Abdennebi M, Ouni M. Reproductive performances and kid's mortality of pure breeds and crossed caprine genotypes in the coastal oases of southern Tunisia. Pakistan Journal of Biological Sciences: PJBS.

[71] Gaddour A, Najari S, Abdennabi M, Ouni M. Dairy performances of the goat genetic groups in the southern Tunisia. Agricultural Journal. 2007;**2**:248-253

[72] Gaddour A, Najari S, Ouni M. Productive performance of pure breeds and cross-bred goat genotypes in southern Tunisia. Options Méditerranéennes, Series A.

[73] Dunne J, di Lernia S, Chodnicki M, Kherbouche F, Evershed RP. Timing and pace of dairying inception and animal husbandry practices across Holocene North Africa. Quaternary International. 2018;**471**:147-159. https:// doi.org/10.1016/j.quaint.2017.06.062

[69] Ammar H, Ben Younes M, López S, Hochlef H. Characterization of goat breeding systems in semi arid regions of northern Tunisia. Revue des Régions Arides-Numéro spécial-Actes du séminaire international: Gestion des ressources et applications biotechnologiques en aridoculture et cultures oasiennes: Perspectives pour la valorisation des potentialités du Sahara.

[60] McKusick BC, Thomas DL, Berger YM, Marnet PG. Effect of milking intervals on alveolar versus cisternal milk accumulation and milk production and composition in dairy ewes. Journal of Dairy Science. 2002;**85**:2197-2206. DOI: 10.3168/jds.

S0022-0302(02)74299-9

pp. 227-232

2008;**5**(2):144-148

Sousse, Tunisia

2007:79

2009. pp. 255-263

faostat.fao.org

[61] Such X, Caja G, Fernandez N, Molina MP, Torres A. The effects of type of pulsator on their evolution of emission kinetics during machine milking in Manchega ewes. In: Barillet F, Zervas NP, editors. Milking and Milk Production of Dairy Sheep and Goats. Wageningen: EAAP Publication, Wageningen Academic Publishers; 1999.

[62] Mohamed A, Khaldi B, Rekik B, Khaldi G. Normal and residual milk yields in Sicilo-Sarde ewes: Effect of litter size and the weaning age of lambs. Research Journal of Animal Sciences.

[63] Saâdoun L, Romdhani SB, Darej C, Djemali M. Performance recording of animals: State of the art 2004. In: Proceedings of the 34th Biennial Session of ICAR; 28th May-3rd June 2004;

[64] Sâadoun L. Simplification du contrôle laitier chez la brebis Sicilo-Sarde et injection de nouveaux gènes par insémination artificielle intra-utérine. Mémoire de Mastère de l'Institut National Agronomique de Tunisie.

[65] Mohamed AR, Khaldi G. The adoption of technical and organizational

innovations and their impacts on dairy sheep breeding in Tunisia. In: New Trends for Innovation in the Mediterranean Animal Production.

[66] FAOSTAT. FAOSTAT. Rome: FAO; 2009. Available from: http://www.

**50**

[75] Schaeffer LR. Applications of random regression models in animal breeding. Livestock Production Science. 2004;**86**:35-45. DOI: 10.1016/ S0301-6226(03)00151-9

[76] Dag B, Keskin I, Mikailsoy F. Application of different models to the lactation curves of unimproved Awassi ewes in Turkey. South African Journal of Animal Science. 2005;**35**:238-243

[77] Keskin I, Dag B. Comparison of different mathematical models for describing the complete lactation of Akkaraman ewes in Turkey. Asian-Australasian Journal of Animal Sciences. 2006;**19**:1551-1555

[78] Amin AA. Test-day model of daily milk yield prediction across stages of lactation in Egyptian buffaloes. Archiv Tierzucht. 2003;**46**:35-45. DOI: 10.5194/ aab-46-35-2003

[79] Grzesiak W, Wojcik J, Binerowska B. Prediction of 305-day first lactation milk yield in cows with selected regression models. Archiv Tierzucht. 2003;**46**:215-226. DOI: 10.5194/ aab-46-213-2003

[80] Meraï A, Gengler N, Hammami H, Rekik M, Bastin C. Non-genetic sources of variation of milk production and reproduction and interactions between both classes of traits in Sicilo-Sarde dairy sheep. Animal. 2014;**8-9**:1534-1539. DOI: 10.1017/ S1751731114001347

[81] Djemali M, Bedhiaf-Romdhani S, Iniguez L, Inounou I. Saving threatened native breeds by autonomous production, involvement of farmers' organization, research and policy makers: The case of the Sicilo-Sarde

breed in Tunisia, North Africa. Livestock Science. 2009;**120**:213-217. DOI: 10.1016/j.livsci.2008.07.011

[82] Carta A, Casu S, Salaris S. Invited review: Current state of genetic improvement in dairy sheep. Journal of Dairy Science. 2009;**92**:5814-5833. DOI: 10.3168/jds.2009-2479

**53**

after a water is cut to prevent diarrhea.

**1. Introduction**

**Keywords:** nutritional disorders, deficiency, dairy sheep, gestation

The development of ruminant livestock farming in the Mediterranean area involves different sciences (nutrition, reproduction, genetics, health) which must be conducted in parallel and in an integrated way in a breeding system. The conditions of the rearing environment (temperatures, humidity, pathologies, forage quality, etc.) are difficult and limit individual performance (production of milk and meat). Ruminant feeding in the tropics has been the subject of much work, and several approaches have been developed. The first approach focused on improving the quality of the basic ration. The low nutritional value of tropical forage is one of the main factors limiting animal performance [1]. Various works were carried

**Chapter 3**

Sheep

**Abstract**

Nutrition for Lactation of Dairy

The feeding of dairy sheep has to start exactly at the beginning of the last 2 months of gestation (the last third of gestation) and not after lambing. Indeed, during this critical physiological stage, the rumen is compressed by the uterus. Therefore, the ewe can no longer ingest the amount of food that can satisfy its ingestion capacity (2–2.5 kg DM/100Kg of weight/speed) which leads to a controversial situation therein the fact that on the one hand the needs are high (maintenance and gestation) and on the other hand the ingestion capacity is decreasing. To solve this issue, we should give the ewe a supplement based on good quality food that is not heavy and that favors rapid digestive transit. Thus, this supplement must be a concentrated feed distributed at a rate of 0.3 FU/ewe/day), during the last 2 months of gestation. This feeding technique makes it possible to have vigorous lambs at birth, a satisfactory colostrum production which makes it possible to give the lambs the antibodies, necessary for their passive immunity, and therefore reduce the perinatal mortality rate as well as allow for a good triggering of milk production which will be increased in the quantity produced and the peak of lactation. In general, the ration must always be balanced in energy and protein. Indeed, if the ration is surplus in energy, it can cause the infertility of ewes. If it is the other way around, the urea will be stored in the liver and transformed into the urine. However, if the excess is intolerable, it will persist in the liver and cause mortality of the animals and diseases, such as alkalosis. In addition to proteins and energy, ewes must receive the necessary minerals, mainly Ca and P, during pregnancy and lactation. A deficiency of Ca at the end of gestation will cause milk fever (hypocalcemia) which will not be recoverable later. Finally, excessive watering should be avoided

*Houcine Selmi, Amani Bahri and Hamadi Rouissi*

#### **Chapter 3**
