ARTIFICIAL INSEMINATION IN FARM ANIMALS - Phenix-Vet

230Artificial Insemination in Farm Animalsembryos (6.72±1.78 vs 3.09±1.36) in the PUFAs treatment than in the control treatment,respectively.On the contrary, Childs et al. (2008b) fed cows with a ration enriched with n-3 PUFAs anddid not observe any effect on the number of normal embryos nor in the amount of goodquality embryos (grade 1 and 2); however, these cows showed a lower number ofdegenerated embryos. Similarly, Bilby et al. (2006d) did not find an effect of fatty acids inthe ration of dairy cows on the quality of embryos after maturation and in vitro fertilization.In a similar way, Thangavelu et al. (2007) did not establish a difference in the total numberof transferable embryos of dairy cows supplemented with either PUFAs or saturated fat.Marques et al. (2007) did not observe any effect of the addition of arachidonic oreicosapentaenoic acids to the culture media for the in vitro maturation of ovocytes on thesubsequent embryo development. This agrees with observations by Lawson et al. (2007)who added increasing amounts of eicosapentaenoic acid to the culture media for thematuration of ovocytes in vitro. In a recent study, Wakefield et al. (2007) suggested thatcontrary to the possible beneficial effects, supplementing a ration with n-3 PUFAs duringthe period just before or immediately after conception, may reduce normal development ofthe embryo, since this seems to disturb mitochondrial metabolism. Leroy et al. (2010)cultivated bovine zygotes in media supplemented with serum from heifers fed rations witha high content of lipids protected from rumen biohydrogenation and observed a lowerproduction of blastocysts compared to a control treatment, noting that in the first there wasa greater expression of genes related to apoptosis.Even when in vivo and in vitro studies have shown a better embryo development withrations supplemented with lipids, results are not consistent and it is important to ascertainin particular, which fatty acids are the most beneficial for embryo survival (Santos et al.,2008). Oocytes of all mammals contain an endogenous lipid reserve. This feature reflectstheir common ancestral origin, the yolk-rich amniote egg. However, lipids are speciesspecificin terms of their apparent abundance and utilization. Despite the significant role ofthe lipid reserves in cell structure and function, very few studies have provided detaileddescriptions of its nature and composition in mammalian oocytes. Table 5 gives the fattyacid composition of total lipid extracted from zone-intact oocytes of cattle and sheep.6. ConclusionData reviewed shows that supplementation with different sources of lipids and fatty acidsimprove reproductive performance of the female ruminant. However, it is important toconsider that the optimum response will be achieved when undernutrition status of thefemale is not extremely sever. A nutrient balance (protein:energy) in the ration consumed bythe animal is fundamental to obtain maximum benefit from supplementation with fat, sincefatty acids do not supply nitrogen for amino acid synthesis and consequently for the correctfunctioning of the hypothalamus-hypophysis axis. Improvements in reproductiveperformance may be a result of increased energy density of the ration or of the direct effectsof specific fatty acids on reproductive processes. As is the case for any technology ormanagement strategy that improves specific aspects of ovarian physiology and cyclicactivity, actual improvements in pregnancy rate or total weight of calf weaned aredependent on a variety of management practices and environmental conditions. Until theseinterrelationships are better understood, livestock producers are recommended to attemptto formulate low cost/balanced rations. If a source of supplemental fat is available locally