**2. Swine slurry: generation and characteristics**

#### **2.1 Origin of swine slurry**

The swine slurry generation is related to the growth phase and its water/food requirements. Thus, lactation and reproduction phases have a great water supply (12.2–41.1 L water/animal d), mainly related to hydration improvement or fertility [4, 5]. Meanwhile, fattening and weaning have a greater food intake (1.9 kg food/ animal d), exclusively given by increased weight or age [5, 6].

The swine diet is based on proteins, carbohydrates and starch concentrates, which exceed 50% of food total composition [7]. Indeed, fattening tends to prioritize the protein intake (>30%) [6]; while, reproduction and weaning consume mainly fiber (10%) to avoid overweight [8]. In both cases, the low food digestibility could generate nitrogen excretion (<30%) and phosphorus (<10%) [9]. This factor can be observed in the swine conversion index, which can vary from 2.0 to 4.3 and 0.9 to 2.3 kg feed/kg weight gained for fattening and previous phases, respectively [6, 10–12]. Indeed, digestibility can vary depending on the food and animal type, being slightly lowers in the final growth phases (fattening ~ 25%) than initial phases (weaning >50%).

Finally, the water/food ratios allow indirectly evaluating the swine slurry quantity and its composition. Thereby, initial phases (weaning) generate the water/feed ratios from 4.4 to 5.1 L water/kg food [8]; while, final phases (fattening) reaches values from 1.6 to 2.5 L water/kg food [11]. This indicator is indirectly related with nitrogen concentrations from urine/feces values. Indeed, greater urine/feces values are obtained by fattening (6.6–9.1) than weaning (5.5–6.3) [13]. At this point, it's important to note that within the swine excreta around 75% of the nitrogen is in urine, so a higher water intake will increase the nitrogen generation in the slurries [14] (**Table 1**).

#### **2.2 Generation and physicochemical characteristics**

The physicochemical composition from swine slurries will be influenced by the low digestibility of nitrogen (<33%), phosphorus (<32%) and micronutrients (<3%) [9, 17], as well as the animal growth phase [18]. Initial phases (maternity and lactation) produce more slurries (10.0–41.1 L/animal d) than weaning-fattening (3.5–9.10 L/animal d) [4–6]. This could be related with dilution by more water intake. **Table 2** summarizes the physicochemical characteristics from swine slurries according to the growth phase. The main differences are related to a higher content of organic matter (1.8–2.4 times), nitrogen (1.3–2.8 times) and phosphorus (2.1–4.6 times) from fattening with respect to maternity and weaning. This condition is related to a higher food intake (1.7 times), which is made up of carbohydrates and proteins [14]. Meanwhile, micronutrients, such as zinc are excreted (2.7–13.0 times) in the initial phases (weaning). In a different proportion, copper is excreted by swine slurries, increasing during fattening (1.5–7.2 times). Differences in the

**83**

**2.3 Ecotoxicological characteristics**

*Physicochemical characteristics from swine slurries.*

*Nutrients Cycle within Swine Production: Generation, Characteristics, Treatment…*

Wheat and soybeans (12–20%) 2.22–2.35 —

**weight gained**

Pellet 2.13–3.33 — [15] With/out phytases 2.00–4.32 — [6]

Intensive/organic 2.70–3.20 — [10] Ad libitum 2.95–3.05 1.99–2.60 [11] Wean/mat/fat food 0.98–2.14 2.00–20.00 [12, 16]

**Parameter Unit Maternity Weaning Fattening Reference** Slurry L/animal d 10.0–16.0 23.5–41.1 3.5–9.1 [4–6] pH 7.5 6.9 7.2–8.4 [6, 18, 20–22] EC mS/cm 12.8–15.5 14.2 15.3–25.3 [18, 21, 22, 24] TS % 1.7 2.7 3.2 [18, 19, 24] BOD5 g/L 9.0 25.0 16.6–21.6 [18, 22, 24, 25] COD g/L 24.0 65.2 45.3–57.7 [6, 18, 22, 24, 25] TN g/L 1.8–2.3 2.3 2.4–4.6 [6, 18–22, 24, 25]

<sup>+</sup> g/L 1.4–1.8 1.5 2.0–3.1 [6, 18–22, 24, 25]

TP g/L 1.4 0.6 0.8–2.8 [18–22] K g/L 2.2 1.8 1.9–3.8 [18–22] Cl<sup>−</sup> g/L 3.6 2.3 5.1 [18, 24] Cu mg/L 11.0 55.0 15.9–80.0 [18, 22, 24, 26] Zn mg/L 75.0 533.0 40.7–191.0 [18, 22, 24, 26]

**Water/food ratio L water/kg feed**

**Growth phase**

**Reference**

**Feed type Conversion index kg feed/kg** 

presence of copper and zinc excreted is related to the use of both metals as growth promoters and specifically copper that is used additionally for therapeutic purposes (fighting diarrhea) in the most vulnerable swine population (weaning) [17]. Chloride, ammonium and potassium salts may also be present within swine slurries. The feeding has influenced a greater salts excretion (1.4–2.3 times) during weaningfattening. These characteristics are related to the fact that the salts in the swine feeding, favor the liquids retention increasing weight during the growth [18]. On the other hand, raw swine slurries show agronomic properties (N:P: K between 1.1:0.6:1.0 and 1.3:0.4:1.0) [18–22]. Indeed, the nutritional requirements of cereal crops (e.g. corn, wheat) can reach values of N:P: K between 1.2:0.2:1.0 and 1.6:0.3:1.0 [23]. However, the presence of pathogenic organisms and microcontaminating (metals, antibiotics) may limit their use prior to treatment.

Swine slurries have ecotoxicological characteristics depending on the bioindicator used. **Tables 3** and **4** summarize the ecotoxicological characteristics (swine slurries and composition) on terrestrial and aquatic bio-indicators. The ecotoxicological

*DOI: http://dx.doi.org/10.5772/intechopen.89733*

*Productive indicators within swine production.*

**Table 1.**

N-NH4

**Table 2.**


*Nutrients Cycle within Swine Production: Generation, Characteristics, Treatment… DOI: http://dx.doi.org/10.5772/intechopen.89733*

#### **Table 1.**

*Livestock Health and Farming*

**2.1 Origin of swine slurry**

phases (weaning >50%).

and demanding lifestyles have promoted a higher swine meat demand (25 kg/per capita year). Meanwhile, developing countries consume only 8 kg/per capita year, condition related mainly with subsistence habits. However, developing countries (75% worldwide population) concentrates 64% (43.3 million ton/year) of the swine meat total consumption; while that, developed countries concentrate 36% (34.4 million ton/year) remaining. However, emergency economies (Brazil and China) are increasing about 21% the swine meat consumption per capita of their popula-

The swine slurry generation is related to the growth phase and its water/food requirements. Thus, lactation and reproduction phases have a great water supply (12.2–41.1 L water/animal d), mainly related to hydration improvement or fertility [4, 5]. Meanwhile, fattening and weaning have a greater food intake (1.9 kg food/

The swine diet is based on proteins, carbohydrates and starch concentrates, which exceed 50% of food total composition [7]. Indeed, fattening tends to prioritize the protein intake (>30%) [6]; while, reproduction and weaning consume mainly fiber (10%) to avoid overweight [8]. In both cases, the low food digestibility could generate nitrogen excretion (<30%) and phosphorus (<10%) [9]. This factor can be observed in the swine conversion index, which can vary from 2.0 to 4.3 and 0.9 to 2.3 kg feed/kg weight gained for fattening and previous phases, respectively [6, 10–12]. Indeed, digestibility can vary depending on the food and animal type, being slightly lowers in the final growth phases (fattening ~ 25%) than initial

Finally, the water/food ratios allow indirectly evaluating the swine slurry quantity and its composition. Thereby, initial phases (weaning) generate the water/feed ratios from 4.4 to 5.1 L water/kg food [8]; while, final phases (fattening) reaches values from 1.6 to 2.5 L water/kg food [11]. This indicator is indirectly related with nitrogen concentrations from urine/feces values. Indeed, greater urine/feces values are obtained by fattening (6.6–9.1) than weaning (5.5–6.3) [13]. At this point, it's important to note that within the swine excreta around 75% of the nitrogen is in urine, so a higher water

The physicochemical composition from swine slurries will be influenced by the low digestibility of nitrogen (<33%), phosphorus (<32%) and micronutrients (<3%) [9, 17], as well as the animal growth phase [18]. Initial phases (maternity and lactation) produce more slurries (10.0–41.1 L/animal d) than weaning-fattening (3.5–9.10 L/animal d) [4–6]. This could be related with dilution by more water intake. **Table 2** summarizes the physicochemical characteristics from swine slurries according to the growth phase. The main differences are related to a higher content of organic matter (1.8–2.4 times), nitrogen (1.3–2.8 times) and phosphorus (2.1–4.6 times) from fattening with respect to maternity and weaning. This condition is related to a higher food intake (1.7 times), which is made up of carbohydrates and proteins [14]. Meanwhile, micronutrients, such as zinc are excreted (2.7–13.0 times) in the initial phases (weaning). In a different proportion, copper is excreted by swine slurries, increasing during fattening (1.5–7.2 times). Differences in the

intake will increase the nitrogen generation in the slurries [14] (**Table 1**).

**2.2 Generation and physicochemical characteristics**

tion, concentrating swine meat consumption in these countries [3].

**2. Swine slurry: generation and characteristics**

animal d), exclusively given by increased weight or age [5, 6].

**82**

*Productive indicators within swine production.*


#### **Table 2.**

*Physicochemical characteristics from swine slurries.*

presence of copper and zinc excreted is related to the use of both metals as growth promoters and specifically copper that is used additionally for therapeutic purposes (fighting diarrhea) in the most vulnerable swine population (weaning) [17]. Chloride, ammonium and potassium salts may also be present within swine slurries. The feeding has influenced a greater salts excretion (1.4–2.3 times) during weaningfattening. These characteristics are related to the fact that the salts in the swine feeding, favor the liquids retention increasing weight during the growth [18].

On the other hand, raw swine slurries show agronomic properties (N:P: K between 1.1:0.6:1.0 and 1.3:0.4:1.0) [18–22]. Indeed, the nutritional requirements of cereal crops (e.g. corn, wheat) can reach values of N:P: K between 1.2:0.2:1.0 and 1.6:0.3:1.0 [23]. However, the presence of pathogenic organisms and microcontaminating (metals, antibiotics) may limit their use prior to treatment.

#### **2.3 Ecotoxicological characteristics**

Swine slurries have ecotoxicological characteristics depending on the bioindicator used. **Tables 3** and **4** summarize the ecotoxicological characteristics (swine slurries and composition) on terrestrial and aquatic bio-indicators. The ecotoxicological

#### *Livestock Health and Farming*


#### **Table 3.**

*Ecotoxicological characteristics on aquatic organisms.*


**85**

*Nutrients Cycle within Swine Production: Generation, Characteristics, Treatment…*

studies have been carried out mainly in *Daphnia magna*, establishing higher acute toxicity at low concentrations (48 h-LC50, 1.8–3.3%) [27, 28]. Meanwhile, chronic ecotoxicity has been observed on *Lepidium sativum* L. (growth inhibited at concentrations from 3 to 10%, v/v) [29]. However, *Eisenia foetida* growth (6000–20,000

salts, metals, antibiotics, among others separately can generate effect at different

Thus, ammonium on cladoceran aquatic organisms (*Ceriodaphnia dubia, Moina macrocopa, Daphnia carinata, Monia australiensis*) generate mortality at values above

+

+

/L [36]. In the soil, toxic effects of NH4

) has also been reported at concentrations less than 25% [30]. Nutrients,

/L [31–33]. Indeed, ammonium causes enzymatic inhibition and cell

(>8) and/or temperature increasing [35]. Indeed, *Daphnia magna* shows acute toxicity at ammonia concentrations above 2.9 mg/L [34]. Meanwhile, organisms of higher trophic levels (*Penaeus semisulcatus*) reports acute toxicity at concentrations from

mainly in vegetable species, generating necrosis, reduction/stimulation of growth and sensitivity to frost [38]. Indeed, *Lactuca sativa* and *Hordeum vulgare* report chronic effects (growth decreasing) at concentrations from 0.002 mg NH3/L [37, 38]. Chlorides can exceed 1 g/L within swine slurries, being reported less acute toxicity of NaCl (1020–3240 mg/L) on *Daphnia magna* than Cl2 (0.1–0.2 mg/L) [18, 31, 34]. However, toxic effect is decreased at high trophic levels (the chlorinated compounds toxicity decreases on higher trophic levels (*Oncorhynchus mykiss*)), reaching concentrations above 20 g/L [39]. In terrestrial environments, chlorides can cause chronic effects on the vegetal germination [40]. Swine slurries are compound also by micronutrients (copper and zinc), which not exceeds 0.5 g/L [26]. However, acute toxicity on aquatic organisms (*Danio rerio*) reaches concentrations about 0.1 mg/L and on terrestrial (*Eisenia foetida*) it is not exceeding at values of

The odoriferous characteristics within swine slurries are evaluated using analytical methods (compounds) and sensory methods (odor) [46]. Olfactometric

odor precursor compounds from the swine production will be given by the protein's presence from food, generating sulfurous, indole, phenolic and long-chain fatty acids [47–49]. Meanwhile, carbohydrates generate short-chain or volatile fatty acids (less than 6 carbons) [40]. Thus, biological and chemical conditions determine the odor compounds formation. It has been possible to establish the presence of some autochthonous microorganisms (*Streptococcus, Peptostreptococcus, Eubacterium, Lactobacilli, Escherichia, Clostridium, Propionibacterium, Bacteroides, Megasphaera*, among others). Incomplete anaerobic digestion from these microorganisms produce and/or reduce macromolecules to odor compounds, so intermediates (e.g. volatile fatty acids) and finals (e.g. sulfides) [50, 51]. However, not only microorganisms can condition the odorant compounds formation, but also environmental conditions (pH and temperature), which active biological and chemical

type/time of slurries storage. [47]. Indeed, fattening phase (2.1–5.6 times) has more odor than maternity/weaning. On the other hand, fresh swine slurries (1.5–5.4 times) generate more odor than stored slurries (2 months). These results have also shown the odor relationship with volatile compounds presence, which from by diet or slurries management. Thereby, sulfur, ammonia, phenolic and volatile fatty acid compounds from swine slurries influence the odor generation, which show differ-

characteristics measured as odor concentration (OC/m3

within swine slurries reaches values above 1 g/L [18].

is instable transforming to NH3 under alkaline pH

/NH3 have been observed

) are influenced by the

+

= 0.66–0.89) with the generated odor [46]. Particularly,

*DOI: http://dx.doi.org/10.5772/intechopen.89733*

worms/m2

7.5 mg NH4

11 to 55 mgNH4

249 mg/L [41–43].

**2.4 Olfatometric characteristics**

ent correlation degree (R<sup>2</sup>

levels. On the one hand, NH4

disruption [34]. Moreover, NH4

+

+

#### **Table 4.**

*Ecotoxicological characteristics terrestrial organisms.*

#### *Nutrients Cycle within Swine Production: Generation, Characteristics, Treatment… DOI: http://dx.doi.org/10.5772/intechopen.89733*

studies have been carried out mainly in *Daphnia magna*, establishing higher acute toxicity at low concentrations (48 h-LC50, 1.8–3.3%) [27, 28]. Meanwhile, chronic ecotoxicity has been observed on *Lepidium sativum* L. (growth inhibited at concentrations from 3 to 10%, v/v) [29]. However, *Eisenia foetida* growth (6000–20,000 worms/m2 ) has also been reported at concentrations less than 25% [30]. Nutrients, salts, metals, antibiotics, among others separately can generate effect at different levels. On the one hand, NH4 + within swine slurries reaches values above 1 g/L [18]. Thus, ammonium on cladoceran aquatic organisms (*Ceriodaphnia dubia, Moina macrocopa, Daphnia carinata, Monia australiensis*) generate mortality at values above 7.5 mg NH4 + /L [31–33]. Indeed, ammonium causes enzymatic inhibition and cell disruption [34]. Moreover, NH4 + is instable transforming to NH3 under alkaline pH (>8) and/or temperature increasing [35]. Indeed, *Daphnia magna* shows acute toxicity at ammonia concentrations above 2.9 mg/L [34]. Meanwhile, organisms of higher trophic levels (*Penaeus semisulcatus*) reports acute toxicity at concentrations from 11 to 55 mgNH4 + /L [36]. In the soil, toxic effects of NH4 + /NH3 have been observed mainly in vegetable species, generating necrosis, reduction/stimulation of growth and sensitivity to frost [38]. Indeed, *Lactuca sativa* and *Hordeum vulgare* report chronic effects (growth decreasing) at concentrations from 0.002 mg NH3/L [37, 38].

Chlorides can exceed 1 g/L within swine slurries, being reported less acute toxicity of NaCl (1020–3240 mg/L) on *Daphnia magna* than Cl2 (0.1–0.2 mg/L) [18, 31, 34]. However, toxic effect is decreased at high trophic levels (the chlorinated compounds toxicity decreases on higher trophic levels (*Oncorhynchus mykiss*)), reaching concentrations above 20 g/L [39]. In terrestrial environments, chlorides can cause chronic effects on the vegetal germination [40]. Swine slurries are compound also by micronutrients (copper and zinc), which not exceeds 0.5 g/L [26]. However, acute toxicity on aquatic organisms (*Danio rerio*) reaches concentrations about 0.1 mg/L and on terrestrial (*Eisenia foetida*) it is not exceeding at values of 249 mg/L [41–43].

## **2.4 Olfatometric characteristics**

The odoriferous characteristics within swine slurries are evaluated using analytical methods (compounds) and sensory methods (odor) [46]. Olfactometric characteristics measured as odor concentration (OC/m3 ) are influenced by the type/time of slurries storage. [47]. Indeed, fattening phase (2.1–5.6 times) has more odor than maternity/weaning. On the other hand, fresh swine slurries (1.5–5.4 times) generate more odor than stored slurries (2 months). These results have also shown the odor relationship with volatile compounds presence, which from by diet or slurries management. Thereby, sulfur, ammonia, phenolic and volatile fatty acid compounds from swine slurries influence the odor generation, which show different correlation degree (R<sup>2</sup> = 0.66–0.89) with the generated odor [46]. Particularly, odor precursor compounds from the swine production will be given by the protein's presence from food, generating sulfurous, indole, phenolic and long-chain fatty acids [47–49]. Meanwhile, carbohydrates generate short-chain or volatile fatty acids (less than 6 carbons) [40]. Thus, biological and chemical conditions determine the odor compounds formation. It has been possible to establish the presence of some autochthonous microorganisms (*Streptococcus, Peptostreptococcus, Eubacterium, Lactobacilli, Escherichia, Clostridium, Propionibacterium, Bacteroides, Megasphaera*, among others). Incomplete anaerobic digestion from these microorganisms produce and/or reduce macromolecules to odor compounds, so intermediates (e.g. volatile fatty acids) and finals (e.g. sulfides) [50, 51]. However, not only microorganisms can condition the odorant compounds formation, but also environmental conditions (pH and temperature), which active biological and chemical

*Livestock Health and Farming*

Swine slurries

Nutrients

Metals

Salts

**Table 3.**

*%\* = percentage concentration.*

Swine purines

Nutrients

Metals

Salts

plants

**Table 4.**

Different kind of

*%\* = percentage concentration.*

*Ecotoxicological characteristics terrestrial organisms.*

*Ecotoxicological characteristics on aquatic organisms.*

*Lepidium sativum* L. Growth 24, 48,

**Organism Test Compound Concentration** 

slurry

*Daphnia magna* 48 h-LC50 NH3 2.9–6.9 [34]

*Daphnia magna* 48 h-LC50 Zn 0.05 [41] *Daphnia magna* 48 h-LC50 Cu 0.56 [41] *Daphnia magna* LOEC 14d Cu, Zn 0.12 [44] *Danio rerio* 96 h-LC50 Cu 0.12–0.13 [41]

*Oncorhynchus mykiss* 6 h-LC40 NaCl 20,000 [39] *Daphnia magna* 24-48 h-LC50 NaCl 1020–3240 [31] *Daphnia magna* 48 h-LC50 Cl2 0.1–0.2 [34] *Daphnia pulex* 48 h-LC50 Cl<sup>−</sup> 2042 [45]

> raw swine slurry

> > purine

Growth NaCl 0–1280 [40]

*Lactuca sativa* Growth 7d NH3 0.002 [38]

*Eisenia foetida* 48 h-LC50 Zn 268–439 [43] *Eisenia foetida* 48 h-LC50 Cu 153–249 [43]

**Organism Test Compound Concentration** 

72 h

*Eisenia foetida* Growth 28d Untreated

*Hordeum vulgare* Growth 8d NH4

*Daphnia magna* 48–24 h-LC50 Raw swine

*Moina macrocopa* 24 h-LC50 NH4

*Penaeus semisulcatus* 96 h-LC50 NH4

*Ceriodaphnia dubia* 48 h-LC50 NH4

*Daphnia carinata* 24–48 h-LC50 NH4

*Monia australiensis* 24–48 h-LC50 NH4

**(mg/L o %\***

<sup>+</sup> 231–492 [31]

<sup>+</sup> 11.4–55.9 [36]

<sup>+</sup> 20 [32]

<sup>+</sup> 2.2–2.8 [33]

<sup>+</sup> 7.5–8.5 [33]

**(mg/L o %\***

<sup>+</sup> 0.18 [37]

**)**

3–10\* [29]

25\* [30]

**Reference**

**)**

1.8–5.0 [27, 28]

**Reference**

**84**


#### **Table 5.**

*Olfactometric characteristics from swine slurries.*

(e.g. ammonium/ammonia) processes [52, 53]. Temperature affects the microbial growth rate; while, pH influences the buffer capacity, favoring volatile fatty acids generation [54] (**Table 5**).
