THE EFFECT OF PIT-1 AND PRL GENE POLYMORPHISMS ON PRODUCTION AND FUNCTIONAL TRAITS IN HOLSTEIN-FRIESIAN BLACK-AND-WHITE BULLS

The aim of this study was to investigate the effect of the PIT-1 and PRL gene polymor- phisms on the estimated breeding value of functional traits in dairy cattle. Analyses were conducted on 142 bulls (Holstein-Friesian Black-and-White), in which the frequency of genes and genotypes was determined in three polymorphic loci of the PIT-1 gene and one polymorphic locus in the PRL gene. It was shown that the frequency of alleles in three polymorphic loci of the PIT-1 gene was as follows: T = 0.1338 and G = 0.8662 (IVS4-39G>T), A = 0.1444 and G = 0.8556 (IVS5+438G>A), A = 0.1338 and G = 0.8662 (c.1178G>A), while in the case of the PRL gene (g.8398G>A) it was A = 0.8873 and G = 0.1127, respectively. Results of analyses showed dependencies between gene polymorphism in locus IVS4-39G>T and fat yield in milk and between gene polymorphism in locus IVS5+438G>A and the non-return rate in heifers. For locus c.1178G>A advantageous dependencies were observed be- tween heterozygotes and fat yield and protein in milk. In contrast, no relationship was found between polymorphism in locus g.8398G>A and production and functional traits. However, further studies on a larger population of animals will be required to confirm the reported results.