Relationship between the natural resistance of cows of different genotypes and their dairy productivity

Abstract

Abstract The article considers the regularities of the adaptive ability of cows of different genotypes. The study is based on traits of natural resistance and biochemical analyses of blood serum. Crossbred animals in Group III have been found to have higher indices of the natural resistance of the organism. The metabolism intensity in the animal body was indicated a high immunological status, i.e. the bactericidal activity of blood serum (BABS) of crossbred first-calf heifers was 83.1%, which was higher by 7.4% than the analogs’ indices in Group II and by 5.8% than indices in Group I. Similar results were recorded in terms of the lysozyme activity of blood serum. The highest phagocytic activity (PhA) was also found in crossbred heifers. The increased metabolism in the body of crossbred heifers can be explained by the effect of heterosis.