The influence of bull fathers on the protein content in the milk of daughters of the Brown Swiss breed

The protein-milk index is the level of energy supply to the cow and at the same time a unique scale of the energy level of the entire herd. Manufacturers that increase the mass fraction of protein in daughters' milk have been identified. Their widespread use determines the intensity of the improvement of domestic livestock in protein content. The research was carried out in a breeding reproducer for breeding brown Swiss cattle of the SEC "Suvorovsky" of the Smolensk region. The data of the primary zootechnical accounting of cows of the first calving and their mothers for 2014-2021 using the SELEX farm program are analyzed. The daughters of bulls were divided according to the protein content of their mothers (the average protein from the worst is below 3.2%, the average is 3.2-3.40%, the best is 3.41% and higher). An increase in the milk productivity of offspring in comparison with mothers, depending on the linear affiliation, was revealed. The daughters of the Meridian 90827 genealogical group and the Laddy 125640 line showed the maximum difference with the productivity of mothers in milk yield (1038, 1288 kg), in the Amur 3033 line in fat content in milk (0.44%), in the Laddy 125640 line – protein (0.3%). In the daughters of the producer bull, Fason 2655, the protein content in milk increased by 0.12%, in the daughters of Vigor 3697 – by 0.30%. Their mothers had an average protein in milk below 3.2%. Correlation coefficients in 58.3% of bulls between the protein content of daughters and their mothers are positive.