**4. Experiences in Venezuela**

Experiences in Venezuela with the use of rumen-inert fat enriched with high levels of PUFA are promissory, either dairy and beef cattle, and small ruminants such as goats. Since 2007 the research group in the area of Nutrition - Reproduction interaction, in conjunction with researchers from the area of Animal Production at the College of Veterinary Sciences, Universidad Central de Venezuela, have been working on the effect of the rumen-inert fat enriched with high levels of polyunsaturated fatty acids on the productive and reproductive response in ruminants.

The research has been carried out in different ecological areas, with different types of production, levels of intensification, both in experimental stations and commercial farms, using the supplementation with rumen-inert fat given in different ways: multinutritional blocks (MNB); top-dress supplementation (fat placed on the concentrate supplement), in addition to the use of calcium soaps and mixed with mineral or concentrated supplement.

Regarding the effect of rumen-inert fat enriched with high levels of PUFA on the production of milk in a commercial trial, conducted with multiparous Carora breed cows, we evaluated the milk production during six months, obtaining a higher production per day and per lactation (20% more) in cows supplemented with 400 g of rumen-inert fat enriched with high levels of PUFA (Energras ®) compared to cows in the control group. Results are shown in Table 3.

In crossbred Canary goats under tropical conditions, Salvador *et al*. (2009) evaluated the effect of by-pass fat supplementation (80 g Energras ® / day) on milk production and composition. They reported a beneficial effect on the duration of lactation (+44 d), the milk production (+29.4%) and the content of milk components (41% more fat, and 31.2% more protein), without altering the physical characteristic (WMT, acidity, pH, cryoscopy) of the milk the supplemented goats (Table 4).

#### Effect of Rumen-Inert Fat Enriched with High Levels of Poly-Unsaturated Fatty Acids on the Productive and Reproductive Response in Ruminants 93


Otero (2007; unpublished data)

92 Milk Production – An Up-to-Date Overview of Animal Nutrition, Management and Health

service or by increasing in the overall conception or pregnancy rates.

fat, would be a nutraceutical food.

**4. Experiences in Venezuela** 

milk the supplemented goats (Table 4).

response in ruminants.

in Table 3.

The impact of this type of fat is associated with the energy balance of the animal, particularly in the cow during early lactation, decreasing the deleterious effects of the NEB and improving the reproductive activity during the early postpartum. On this regard, Staples *et al*. (1998) mentioned that 11 out of 18 studies reviewing the effect of fat in cow's reproduction, reported an increase in reproductive performance, either because it improves the conception rate at first

In addition, the supplementation with high levels of PUFA can generate a favorable response in milk production and composition, and an improvement in the fatty acid profile of the milk, particularly the levels of conjugated linoleic acid (CLA). Angulo *et al*. (2005) have described that some anticancer and antidiabetogenic properties of the CLA as well as the prevention of atheroma formation, the potentiation of the immune response and the improvement of bone mineralization. It may also increase levels of essential fatty acids (ω-6 and ω-3) in milk, which can cause the milk produced by cows or goats fed with this type of

Experiences in Venezuela with the use of rumen-inert fat enriched with high levels of PUFA are promissory, either dairy and beef cattle, and small ruminants such as goats. Since 2007 the research group in the area of Nutrition - Reproduction interaction, in conjunction with researchers from the area of Animal Production at the College of Veterinary Sciences, Universidad Central de Venezuela, have been working on the effect of the rumen-inert fat enriched with high levels of polyunsaturated fatty acids on the productive and reproductive

The research has been carried out in different ecological areas, with different types of production, levels of intensification, both in experimental stations and commercial farms, using the supplementation with rumen-inert fat given in different ways: multinutritional blocks (MNB); top-dress supplementation (fat placed on the concentrate supplement), in addition to the use of calcium soaps and mixed with mineral or concentrated supplement.

Regarding the effect of rumen-inert fat enriched with high levels of PUFA on the production of milk in a commercial trial, conducted with multiparous Carora breed cows, we evaluated the milk production during six months, obtaining a higher production per day and per lactation (20% more) in cows supplemented with 400 g of rumen-inert fat enriched with high levels of PUFA (Energras ®) compared to cows in the control group. Results are shown

In crossbred Canary goats under tropical conditions, Salvador *et al*. (2009) evaluated the effect of by-pass fat supplementation (80 g Energras ® / day) on milk production and composition. They reported a beneficial effect on the duration of lactation (+44 d), the milk production (+29.4%) and the content of milk components (41% more fat, and 31.2% more protein), without altering the physical characteristic (WMT, acidity, pH, cryoscopy) of the



\*\* P < 0.01; NS= not significant

(Adapted from Salvador *et al.*, 2009)

**Table 4.** Effect of rumen-inert fat on milk production, days on lactation and composition of crossbred Canary goats

On the other hand, the milk lipid profile can be manipulated when supplementation with rumen-inert fat is given. Milk tends to have low levels of unsaturated fatty acids, being oleic acid (C18:1), a monounsaturated fatty acid, the most abundant (20% approx.). The proportion of unsaturated fatty acids is less than the saturated ones. The formation of the milk fat may come from the *novo* synthesis fatty acids in the mammary gland or from the incorporation of fatty acids from the diet or body reserves. Regarding the long chain fatty acids (including ω-6 and ω-3 fatty acids) which are incorporated in the milk, about 40-45% come from the diet (Palmquist, 1996). Therefore, manipulating the diet by the incorporation of higher levels of fatty acids from rumen-inert fat, could be an strategy to change the milk fat composition in ruminants.

In recent years, the manipulation of milk fat content has taken great importance, with the aim of increasing the concentration of CLA in dairy products, which may contribute significantly to generate milk with nutraceutical properties of essential fatty acids that would contribute to the human health. In this regard, Zamora (2010), supplementing crossbred Canary goats with rumen-inert fat enriched with high levels of fatty acids (45 g/day ENERGRAS®), found significant differences (P<0.01) on oleic and linolenic acids

concentrations between cheeses from treated and control goats: (331.34 ± 63.25 vs. 28.02 ±67.29 mg/g and 9.78 ±1, 22 vs. 5.41 ±1.30 mg/g respectively), when compared to the cheeses made from milk of goats supplemented (treatment vs. control) respectively. In addition, there was a trend in linoleic acid concentrations to be higher in chese from treated goats: (30.26 ±9.74 vs. 19.26 ±10.37 mg/g), not affecting the quality and organoleptic properties of fresh cheeses (Table 5).


NS: No significant; \*: P<0.05; \*\*: P<0.01 (Adapted from Zamora, 2010).

**Table 5.** Effect of rumen-inert fat on performance, characteristics and composition of fresh pasteurized goat's cheese.

In addition, the performance of milk in terms of kilograms of cheese showed no significant differences (P>0.05) between cheese made from milk of goats supplemented with rumeninert fat and cheese made from milk of goats without fat supplementation, (at 0 h and 48 h), after the removal from the mould. Nevertheless, the cheeses made from milk of the treatment group needed less milk to produce 1 kg of fresh cheese (140g and 400g less at 0 and 48 hours after the removal from the mould, respectively). At the moment of curd preparation there was not difference in terms of content of water retained (48.1% and 48.4% for treatment and control groups respectively). This could be due to, the protein content of the serum that could affect the production of cheese (cheese making performance and the drainage of whey, especially when milk from treated goats was heated; Raynal-Ljutovac *et al.,* 2008). However, it is important to mention there were not statistical differences in terms of kg of cheese obtained from treated and control goats, the performance improved for processed cheese made from milk of goats that consumed rumen-inert fat, although they had a higher milk production, there were 47.95 kg of fresh cheese from the treated group and 25.37 kg of fresh cheese in the control group, with a difference of 47.09% for the treatment group.

94 Milk Production – An Up-to-Date Overview of Animal Nutrition, Management and Health

VARIABLE Treatment group

NS: No significant; \*: P<0.05; \*\*: P<0.01 (Adapted from Zamora, 2010).

fresh cheeses (Table 5).

**Performance** 

**Characteristic:** 

**Components:** 

goat's cheese.

concentrations between cheeses from treated and control goats: (331.34 ± 63.25 vs. 28.02 ±67.29 mg/g and 9.78 ±1, 22 vs. 5.41 ±1.30 mg/g respectively), when compared to the cheeses made from milk of goats supplemented (treatment vs. control) respectively. In addition, there was a trend in linoleic acid concentrations to be higher in chese from treated goats: (30.26 ±9.74 vs. 19.26 ±10.37 mg/g), not affecting the quality and organoleptic properties of

Performance to 0 H 3.9 ± 0.1 4.0 ± 0.1 NS Performance to 48 H 4.8 ± 0.1 5.2 ± 0.1 NS

Acidity 13.1 ± 1.7 13.5 ± 1.7 NS Clorures 2.9 ± 0.3 2.9 ± 0.3 NS pH 5.6 ± 0.1 5.4 ± 0.1 NS

fat (%) 24.5 ± 1.2 21.9 ± 1.2 NS Protein (%) 10.2 ± 0.4 10.7 ± 0.4 NS Humidity (%) 48.1 ± 0.9 48.4 ± 0.9 NS Ash (%) 4.3 ± 0.2 4.1 ± 0.2 NS Solids (%) 51.8 ± 0.9 51.5 ± 0.9 NS Solids no fat (%) 27.3 ± 1.3 29.6 ± 1.3 NS Lactose (%) 12.7 ± 1.0 14.6 ± 1.0 NS Oleic C18:1 (mg/g) 331.3 ± 63.2 28.0 ± 67.2 \*\* Linoleic C18:2 (ω-3) (mg/g) 30.2 ± 9.7 19.2 ± 10.3 NS Linolenic C18:3 (ω-6) (mg/g) 9.7 ±1.2 5.4 ± 1.3 \*

**Table 5.** Effect of rumen-inert fat on performance, characteristics and composition of fresh pasteurized

In addition, the performance of milk in terms of kilograms of cheese showed no significant differences (P>0.05) between cheese made from milk of goats supplemented with rumeninert fat and cheese made from milk of goats without fat supplementation, (at 0 h and 48 h), after the removal from the mould. Nevertheless, the cheeses made from milk of the treatment group needed less milk to produce 1 kg of fresh cheese (140g and 400g less at 0 and 48 hours after the removal from the mould, respectively). At the moment of curd preparation there was not difference in terms of content of water retained (48.1% and 48.4% for treatment and control groups respectively). This could be due to, the protein content of

(80 g Energras®/day) Control group Probability

It is important to mention that the rumen-inert fat did not affect the characteristics of the cheese, nor the chemical composition neither of its components, except FA, concentrations and minerals in the treatment group, which had a trend to be higher. Some additional results showed that the effect of the consumption of rumen-inert fat on the proportion of *cis* and *trans* FA found in fresh goat cheese, was not significant (P>0.05). However, the proportion was higher in milk from treated goats than in milk from control goats (95.97 ± 4.31 and 85.73 ± 4.31 respectively) which aggregates a value to the cheese, having a product with unsaturated *cis* FA, which has benefits to human health, because *trans* FA from of partially hydrogenated oils have been linked to deaths due to cardiovascular diseases (Giacopini, 2008).

Regarding to reproductive responses, the use of rumen-inert fat enriched with high levels of PUFA has been evaluated with promising results, particularly in first-calf Brahman cows in areas of well drained savannas in Cojedes States (Farms A and B) and Guárico States (Farm C) with acidic soils, in conditions of limited range and forage quality. In these studies Diaz *et al*. (2008; 2009) used multinutritional blocks that were formulated with the aim of providing non protein nitrogen, rumen-inert protein, minerals (macro and microelements) and rumen-inert fat (with 17% of linoleic acid [ω-6]). In the case of Farm A, the breeding season was during the rainy season, while for the two other farms (B and C) breeding seasons ware during the dry period. Data of pregnancy rate are shown in Figure 2. Results showed higher pregnancy rates than those reported for the same type of animals under tropical conditions (30%). Pregnancy rate for first calf Brahman cows in Farm A during the previous year was 46% much lower than the present results.

Diaz *et al*. (2009) and Hernandez (2010) also reported a beneficial effect of the supplementation with rumen-inert fat enriched with high levels of PUFA, during the postpartum period on ovarian activity of first-calf Brahman cows. Their results showed that supplementation with 150 g of fat/cow/d increased the accumulated number of Class 3 follicles (≥ 10 mm) during the first 90 d post-partum (P<0.06; Figure 3). In this regard Diaz (2009) suggested that a greater accumulated number of Class 3 follicles could be an indicator of a greater likelihood of having preovulatory follicles, so cows would have a greater chance of ovulation during the first 90 d postpartum. On the other hand, it is an indirect indicator of the onset of LH secretion after parturition, as this hormone is responsible for the final maturation of preovulatory follicles and subsequent ovulation.

**Figure 2.** Pregnancy rate for first calf Brahman cows supplemented with multinutritional blocks enriched with rumen-inert fat. The line represents the pregnancy rate for first calf Brahman cows in Venezuela (Adapted from Diaz *et al*., 2008; 2009).

**Figure 3.** Accumulated number of Class 3 follicles (≥ 10 mm) between 30 and 90 d postpartum in firstcalf Brahman cows supplemented or non with-rumen-inert fat.

Also, Hernandez (2010) reported that independent of significant difference in reproductive efficiency parameters between cows supplemented with rumen-inert fat and cows in the control group, there were numeric differences of 14 percentage points in conception rate, in favor of the supplemented cows (91% vs. 77%) and 12 d shorter interval from calving to conception (days open: 90 vs. 102 d in treatment and control group respectively). Those numbers would translate into an increase in reproductive efficiency and therefore the profitability herd.

96 Milk Production – An Up-to-Date Overview of Animal Nutrition, Management and Health

90

**Figure 2.** Pregnancy rate for first calf Brahman cows supplemented with multinutritional blocks enriched with rumen-inert fat. The line represents the pregnancy rate for first calf Brahman cows in

79

Farm A Farm B Farm C

50

Control Tratament

**Figure 3.** Accumulated number of Class 3 follicles (≥ 10 mm) between 30 and 90 d postpartum in first-

Days pospartum

30 33 36 39 42 45 48 51 54 57 60 64 67 70 73 76 79 82 85 88 90

calf Brahman cows supplemented or non with-rumen-inert fat.

Venezuela (Adapted from Diaz *et al*., 2008; 2009).

0

5

10

15

Accumulated Nomber of Class 3 follicles

20

25

30

35

**Pregnancy rate (%)** 

In another experiment (cows received 250 g of rumen-inert fat/cow/d) we found a 20% reduction in the interval between calving and first estrus (control cows: 98 d *vs*. 78 d in supplemented cows). In this case the fat used as a supplement contained 5% ω-3 and 17% ω-6, (Unpublished data). It is important to note that the cows supplemented with ω-6 presented problems of consumption at the beginning of the trial.

Diaz *et al*. (2009) considered that the ω-6 fatty acids should be provided to stimulate cyclic ovarian activity early in the post-partum, while the ω-3 fatty acid (linolenic acid, DHA and EPA) should be supplied during early pregnancy. In this regard, several authors (Petit *et al.,* 2002;) Mattos *et al*., 2003) indicate that ω-6 fatty acids stimulate synthesis of PGF2α, as well as ω-3 stimulates the synthesis of series 3 prostaglandins, which can block the synthesis of the former, specifically the PGF2α by competitive inhibition of enzymes that regulate their synthesis.

However, there are contrasting evidences regarding the role of the ω-6 fatty acids and the synthesis of PGF2α. To this respect, Staples *et al*. (2002), indicate that linoleic acid has inhibitory effects both *in vitro* and *in vivo*, probably dose related, as the excess of this fatty acid might reduce the synthesis of prostaglandins in series 1 and 2 (i.e., PGF2α). These same authors point out, that the inhibition may be due to a competitive effect with arachidonic acid by the prostaglandin endoperoxide synthase enzyme (PGSH). Therefore, a rich source of ω-6 fatty acids could reduce the synthesis of PGF*2α*, prolonging the lifespan of the corpus luteum, allowing the implantation of the embryo and decreasing the early embryonic mortality.

On the other hand, Diaz *et al.* (2009) argue that both the maintenance of pregnancy, and the onset of postpartum ovarian activity may occur with the single supply of linoleic acid. Therefore, the use of rumen-inert fat enriched with high levels of ω-6 and/or ω-3 could contribute positively on uterine involution, the resumption of postpartum ovarian activity and reduction of days open in beef and dairy cows.
