Enzyme blood profile in lactating cows of different bulls’ genetic lines

Scientific and production experiments were carried out on lactating cows of the Simmental breed. 4 groups of cows derived from different lines of bulls Romulus, Redad, Huxle, and Honig were formed for the experiment. Each group contained 10 heads. The level of dairy productivity of experimental cows was the same and amounted to about 11 thousand kg of milk per lactation. The keeping conditions for the animals were the same. Feeding levels were consistent with their dairy productivity. Blood for the study was taken once a month prior to morning feeding. The following were determined in blood samples: total protein, alanine aminotransferase (ALT), aspartate aminotransferase (AAT), alkaline phosphatase (AP) and lactic dehydrogenase (LDH). During lactation, the highest level of total protein, the activity of ALT, AAT, AP, LDH was observed at the peak of lactation, followed by their decrease by the end of lactation regardless of cows’ genetic affiliation. Relatively higher levels of total protein and ALT, AAT and LDH activity have been observed in lactating cows of the bull line Romulus relative to cows of the bull lines Redad, Huxle and Honig. There were no differences within the cows’ genetic lines in the activity of alkaline phosphatase