Abstract
The transition period is considered of great importance in the production cycle of dairy cows due to the occurrence of various changes in animal metabolism and physiology. These alterations, mediated by hormonal and metabolic responses, result from the modification of the prevailing physiological condition, when the animal goes from a pregnant and non-lactating condition to a non-pregnant and lactating one, in which alterations in animal feeding and management can result in marked changes in the metabolism by the modification of these animals productive and reproductive performance during the production cycle. Recent studies show that dietary supplementation with polyunsaturated fatty acids as an energy source, in addition to increasing the energy density of the diet, may be potent metabolism regulators and may positively influence the hepatic, adipose, mammary, reproductive and immune functions (nutraceutical function). Despite efforts in some research centers in conducting projects in this area, these studies revealed the need to expand the number of projects conducted because of the complexity of the theme. Since most research on lipids for ruminants are concentrated in nutritional outcomes, results that correlate the influence of fatty acids supplementation and reproductive and immune parameters of dairy cows during the transition period are scarce. This scenario highlights the importance and necessity of further research to clearly elucidate the effects of supplementation time with polyunsaturated fatty acids on animal metabolism, with consequent alteration of productive, reproductive and immune responses. In Brazil, research in this area is scarce, and the techniques of laboratory analysis are very outdated compared to developed countries (USA, Canada, Germany and others). Moreover, it is of great importance to estabilish partnerships for improving and learning laboratory analysis techniques related to reproductive and immune system and blood parameters that are more accurate. The objective of the present study is to evaluate the effect of prolonged dietary supplementation with whole soybean grains as a source of unsaturated fatty acids for dairy cows, starting at the prepartum period and continuing through the postpartum period, and the effects on productive performance, oocyte and embryo quality, immune function an plasma concentrations of metabolites at the University of Florida, Gainesville/USA. (AU)
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