INFLUENCE OF THE DIFFERENT TYPES OF CROSSBREEDING OF DAIRY CATTLE BREEDS ON THE IMMUNE STATUS OF COW COLOS-TRUM

The purpose of the study is to evaluate the effects of different types of crossbreeding between the Black and White and Holstein breeds on the chemical composition and immune status of the colostrum of crossbred cows with different blood content to improve the breed. The material of the research was the first milking colostrum and calves obtained from crossbred first-calf cows at introductory, backcross, reproductive and absorbing crossings. It was found that in terms of dry matter content in colostrum, crossbreds with ⅝ G blood content were superior to ½ G by 0.8% (P < 0.05), ¼ G by 0.4% and 15/16 G by 1.4% (P < 0.001). In terms of the mass percentage of fat in the dry matter of the colostrum, ⅝ G crosses were superior to ½ G by 0.5% (P < 0.001), ¼ G by 0.1% and 15/16 G by 0.7% (P < 0.001). In the first portion of cow colostrum, proteins are the most abundant fraction. The difference in the mass fraction of proteins in the dry matter of the colostrum was 0.5% (P < 0.01); 0.3% (P < 0.05); 0.9% (P < 0.001), respectively. The difference in the content of globulins in the proteins of the colostrum, which provide protective function for an organism, was 0.2 % (P < 0.05); 0.3 % (P < 0.001); 0.5 % (P < 0.001), respectively. In contrast, the concentration of immunoglobulins was 7.3 % (P < 0.001); 3.2 % (P < 0.05); 11.0 % (P < 0.001) higher. Thus, the increase in Holstein blood in the absorbing crossing and the decrease in the backcrossing leads to a significant deterioration in colostrum quality and an increase in calf morbidity.