Всероссийский научно-исследовательский институт физиологии, биохимии и питания животных – филиал Федерального государственного бюджетного научного учреждения «Федеральный научный центр животноводства – ВИЖ имени академика Л.К. Эрнста»
ABSTRACT. The experiment was carried out using the Latin square method on three groups of goats, 3 goats each, which were at the beginning of experiment at the 2nd month of lactation. The duration of each periods of experience was three weeks. In the initial period, goats were fed the basic ration (BR) with the recommended level of available protein (DP) and metabolizable energy. In the experimental periods, soybean meal (SBM) was added to the basic ration at an amount of 150 g, corresponding to a 10% increase in available crude protein, and also 90 g of sodium acetate (SA) and 36 g of sodium propionate (SP) per goat per day, which corresponded to 3% of the diet metabolizable energy. At the end of each experimental period, samples of milk and blood were taken from the jugular and milk veins before the morning feeding and 3 and 7 hours after the feeding. Plasma volume flow through the udder was determined by calculating the ratio of the α-amino nitrogen output with milk and arteriovenous difference (ABD) concentration of amino nitrogen in the mammary gland. The activity of transport of amino acids to secretory cells (T, l/h), was estimated in units of clearance (T=Q*E/(1-E), where Q is plasma flow rate, ml/min, and E is efficiency of extraction from the blood, E=100*(ca - cv)/ca; ca and cv are substrate concentration in the blood plasma of the jugular and dairy veins, respectively. When feeding supplements SBM, SBM+SA and SBM+SP, milk productivity increased by 8.2%, 14.7% (P<0.05), 13.3% (P<0.05) and the yield of milk protein by 9, 5%, 18.9% (P<0.05), 16.1% (P<0.05) respectively compared to BR. The addition of acetate or propionate salts to a high-protein diet reduced the level of urea in milk (P<0.05), which indicates a more efficient use of amino acids for productive purposes. The inclusion of protein supplements in the diet increased plasma volume flow rate in the mammary gland. The feeding of protein supplements together with sodium acetate or sodium propionate had an additional stimulating effect on the plasma flow. When included of feed additives in the diet, the activity of amino acids transport to secretory cells was higher compared to BR. Concluded that the identified productive effect was significantly associated with positive changes in the indicators of organ blood flow and the formation of substrate balance in the mammary gland.
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