Evaluation of ruminal biohydrogenation and fatty acids intestinal flux of dairy cows supplemented with different fat sources

Abstract

Using various sources of fat in the dairy cows feed has been common practice in the food, especially for allowing improvement of the energy status of these animals. However, when evaluating the supplementation of feed for ruminant fat sources, all physiological processes must be taken into consideration because ruminal metabolism, intestinal absorption, transport and systemic metabolism, secretion and deposition of fat in the body are aspects directly related to lipid metabolism and may influence the physiological responses of animals receiving fat in diets. The biohydrogenation is an important step in fatty deácidos ruminal metabolism and can be considered self-defense process of the rumen microorganisms which convert unsaturated fatty acids to saturated fatty acids, less toxic to the rumen microbial population. Furthermore, this process reduces the intestinal flow of polyunsaturated fatty acids to the duodenum and contribute to the accumulation of CLA isomers cis and trans in products derived from ruminants depending on the fat source used. Such isomers of CLA have been evaluated and found in products derived from ruminants reared on pasture or receiving diets rich in linoleic and linolenic acids, generally derived from oilseeds such as soybeans, and soy and sunflower oil. While most of the fatty acids is modified through the rumen metabolism, the biohydrogenation is usually not complete, resulting in a wide variety of fatty acids. When there is incomplete biohydrogenation of polyunsaturated fatty acids, an increase of duodenal flow of trans fatty acids - C18: 1 and cis-linoleic acid conjugate 9, trans-11 CLA and trans-10, cis -12 - CLA presenting the first effects nutraceuticals and the last proven inhibitory effect on milk fat synthesis through reduced expression of lipogenic genes. Thus, in addition to being considered an energy source, the fatty acids are also suitable and used as moderators metabolism and physiology. However, the scientific hypothesis to be evaluated in this experiment suggests that, depending on the fat source used, there may be changes in length of the intestinal and ruminal biohydrogenation flow of fatty acids, without affecting, however, the dry matter intake and nutrient, ruminal fermentation, digestibility of nutrients, milk production and its components and the nutrient balance. This experiment will be conducted to evaluate the effects of various sources of dietary fat for lactating cows on the ruminal and intestinal flow of fatty acids, fermentation and synthesis of ruminal microbial protein, consumption and apparent digestibility of dry matter and nutrients, milk yield and composition, blood parameters concentrations, fatty acid profile of ruminal and abomasal digesta, feces, and milk fat, the balance of energy and nitrogen. (AU)