Association of bovine DGAT1 and leptin genes polymorphism with milk production traits and energy balance indicators in primiparous Holstein cows

This study investigated the impact and significance of two polymorphisms located in the DGAT1 and LEP genes on selected milk production traits during the first six months of lactation, with respect to the course of the Holstein primiparous cows' body condition. A total of 278 primiparous Holstein cows were tested for the DGAT1-K232A and LEP C(-963)T mutations using the PCR-RFLP technique. The following allele frequencies were found: K232A - 0.74 (A) and 0.26 (K), C(-963)T - 0.58 (C) and 0.42 (T). The statistically significant influences (P<0.01-0.05) were found for both polymorphisms. Homozygotes AA for DGAT1 were characterized by the highest daily milk production and lowest percentage content of fat during almost all observed months (P<0.01-0.05), which is related to statistically significantly (P<0.01) the lowest fat-to-protein ratio. Cows with CC genotype in LEP gene were characterized by the lowest content of fat during the second month of lactation which affected corresponding fat-to-protein ratio in milk. Body condition score (BCS) level and BC S changes during the first six months of lactations were not influenced by any mutation evaluated.