Research On Animal Production

 Extended Abstract
Background: High-yielding cows, especially at the beginning of the lactation period, are mainly in a negative energy balance. This problem occurs due to energy consumption less than the requirements for high production, which causes the animal to use its body reserves. Therefore, it is necessary to enrich the diet in various ways, one of which is to use fat supplements. Increasing the level of dietary fat is important to provide energy during this period. Fat supplementation can reduce negative energy balance in high-yielding cows. The beneficial effects of fat supplementation depend on its type and amount. Fats should be relatively ineffective to reduce their harmful effects = in the rumen (such as reductions in the ratio of acetate to propionate, fiber digestion, and methane production). Fats reduce fat oxidation in the liver and dry matter consumption in livestock by influencing the hormones of the digestive system. A decrease in the passage rate of digestible substances from the rumen by adding fat to the diet can increase the expansion of the rumen and stimulate the stretch receptors in the rumen, resulting in probably a decrease in dry matter intake. However, the use of fat in feeding dairy cows also has limitations that must be overcome. Using emulsifier compounds can be very important during this period due to the property of emulsifying fats and increasing fat digestion. The emulsifier molecule can be dissolved in water with its hydrophilic part and in fat with its hydrophobic part and plays an important role in helping to form micelles. Therefore, emulsifiers can distribute fat droplets in the emulsion, which is necessary for fat digestion and absorption. Lysophospholipids are among the emulsifying compounds that increase fat digestion and absorption in the diet. Lysophospholipid is a strong feed additive to improve digestion and absorption and increase feed productivity, which increases production, feed efficiency, and absorption of dietary nutrients. In this research, the effects of using this emulsifier on blood and milk biochemical parameters, liver enzymes, and rumen microbial population are studied in the early lactation period of Holstein dairy cows.
Methods: This experiment was carried out on 15 multi-calving Holstein dairy cows (three groups of five cows) with an average weight of 720 ± 50 kg and lactation days of 16 ± 5 days in a completely randomized design. The treatments were three levels of lysophospholipid in the feed (zero, 0.1, and 0.15%) for 35 days. The experimental diets were completely mixed and provided to the cows twice a day in the morning and afternoon. Cows had free access to water. At the end of the experimental period (35 days), blood was taken from the tail vein of randomly selected cows in three replications of each treatment to measure total protein, triglyceride, total cholesterol, blood nitrogen, unesterified fatty acids, and beta-hydroxybutyrate. To check the liver enzymes, blood samples were taken from cows before feed consumption on days 0 and 34 of the experimental period, by applying a 12-hour deprivation of feed consumption, to measure the activity of liver enzymes, viz. alkaline phosphatase (ALP), alanine aminotransferase (ALT), and aspartate aminotransferase (AST). At the end of the experimental period, rumen fluid was obtained from the rumens of all experimental cows to evaluate pH, ammonia nitrogen, volatile fatty acids (VFAs), enzymes, and bacterial and protozoan populations.