Milk productivity of Jersey cows with different PIT1, GH genotypes

This article presents the results of a study on the influence of polymorphism in the pituitary-specific transcription factor (PIT1) and growth hormone (GH) genes on milk productivity of Jersey cows. Polymorphism of these genes can significantly affect both quantitative and qualitative indicators of dairy production. The parameters of 87 animals were analyzed, including milk yield, fat and protein content, milk fat and protein yield. Based on data obtained from the analysis of a herd of first-calf heifers at Timiryazev LLC in Baltasinskiy district of the Republic of Tatarstan, associations were established between various genotypes of the genes under study and milk productivity parameters. It was revealed that, according to PIT1 gene, animals with PIT1 AA genotype have the highest milk yield (6903±387.9 kg) and milk fat yield, while PIT1 AB genotype is associated with the maximum protein content (4.09±0.10%). For the GH gene, a reliable (p<0.05) superiority of GH LL genotype in milk yield (6970±258.8 kg) and milk protein yield (280.9±12.76 kg) was established compared to GH VV genotype. The advantage of LL genotype can be explained by the fact that L allele is associated with a higher level of circulating somatotropin, which contributes to increased productivity. Thus, polymorphism of PIT1 and GH genes has a significant impact on the milk productivity of cows. It was determined that the most desirable genotypes for breeding are PIT1 AA, PIT1 AB, and GH LL. The results of the study can be used to develop marker-assisted selection programs for Jersey cows aimed at increasing milk productivity.