Protein content in milk of holstein black-and-white cows

Abstract

Abstract The most optimal method to solve the problem for cow’s milk and protein content increase is to carry out zootechnical and breeding activities. The goal was to study the milk protein structure and content of the Holsteinized black-and-white breed cows of different genotypes, as well as to establish the relationship nature between the activity of transamination enzymes and the milk protein content of cows. For this purpose, 4 groups of experimental cows (15 heads in each) were formed according to the principle of father’s belonging to the countries of origin (daughters of seed bulls of Canadian, Danish selection, Dutch and domestic selection). The superiority of cows-daughters of foreign breeding bulls in terms of milk protein content was established. Moreover, the milk of cows born from foreign producers contents high level of casein - the most important fraction from the technological point of view. Electrophoretic analysis of milk proteins isolated 16 fractions, including 9 casein and 7 whey ones. The highest content was found in such fractions as αs1-, β-, αs2-, κ-caseins and β-Lg. The calculated correlation coefficients between the alanine aminotransferase and aspartate aminotransferase and the milk protein activity of cows showed a direct relationship between them in cows of the studied groups. This is a favorable factor for increasing the cows milk protein content.