Evaluation of breeding bulls with different genotypes of somatotropin cascade genes for milk productivity and milk quality of the closest female ancestors

A preliminary evaluation towards a breeding value of holstinized Black-and-White breed bulls with different genotypes of somatotropin cascade genes is presented: pituitary transcription factor or growth hormone factor (PIT1), prolactin (PRL), somatotropin (GH), somatotropin releasing hormone (GHRH), insulin-like (IGF-1) in the conditions of the Republic of Tatarstan. The research studies the signs (indices) of milk productivity (milk yield and fat in milk) of the closest female ancestors of bulls with different genotypes of somatotropin cascade genes. Studies and analysis have shown that the highest rating by origin, based on the pedigree index of bull, were bulls with genotypes PIT1/AB, PRL/AA, GH/LL, GHRH/АВ, IGF1/AA (by milk yield) и PIT1/AA, PRL/AB, GH/LV, GHRH/BB, IGF1/BB (by fat content) in comparison with analogues of other genotypes.