Cow's milk productivity: effects of bull's genotype and line

The article presents sire proving results of 11 Holstein stud bulls of three lines of breeding, i.e. Vis Back Ideal 1013415, Reflection Sovering 198998, and Montvik Chieftain 95679. Experimental studies were conducted in the conditions of a dairy complex of OOO agricultural enterprise "Donskoe" in the Volgograd region. Comparative analysis of bulls' daughters in the first complete lactation with their mothers and herdmates showed that the average milk yield of daughters of bulls under study varied within 8256-9895 kg, the fat content values of milk were 3.80-4.30%, and the protein content values ranged from 3.10 to 3.40%. Seven of the sire proved bulls were recognized as improving bulls with varying degrees of genetic potential realized. The Vis Back Ideal 1013415 bulls' daughters were found to have superior milk yield in comparison with the Reflection Sovering 198998 and Montvik Chieftain 95679 bulls' daughters. Moreover, the Reflection Sovering bulls' daughters outnumbered the Vis Back Ideal bulls' daughters in terms of the fat content in milk by an average of 0.1%. The milk yields of all evaluated bulls' daughters exceeded their mothers with respect to the milk yield, which indicated genetic progress over a generation. Thus, the stud bulls that turned out to be improving in terms of the milk yield and fat content will further improve the productive traits of cows.