Abstract

The study presents the results of a study of the bactericidal and lysozyme activity of blood serum of heifers of different breeds. The experiment involved 4 groups of heifers, 10 heads in each group: 1) Black-and-white Holstein; 2) Simmental; 3) Aberdeen-Angus; and 4) crosses of Simmental and Aberdeen-Angus breeds. Animals of all groups were kept in the same feeding and housing conditions. During the experiments, the animals were fed according to generally accepted standards. Blood was taken from animals from the tail vein in the morning before the first feeding in compliance with the aseptic rules. It was found that with an increase in gestation, the activity of serum bactericidal activity (SBA) and serum lysozyme activity (SLA) in the blood of heifers gradually increases.in conclusion, during pregnancy, the level of SBA and SLA in the blood of heifers depended on the month of pregnancy and the breed of animals. During pregnancy, hybrid heifers have higher levels of SBA and SLA, and relatively low levels of SBA and SLA are observed in Black-and-White, Simmental and Aberdeen Angus heifers. © 2021. All Rights Reserved.