Leptin gene polymorphism in Aberdeen Angus cattle in relation to cow productivity indicators

The studies were conducted to substantiate the use of the Y7F, R25C, and A80V polymorphisms of the leptin gene (LEP) as markers of the fattening and reproductive traits of cows. Using PCR-RFLP and PCR-RT, the DNA samples from three experimental groups of Aberdeen-Angus breed were genotyped: second-calving cows (n = 124) with data on reproductive performance, bull calves (n = 71), and heifers (n = 131) with fixed fattening indicators. The population did not include any animals with the FF-Y7F genotype, and only one cow (0.8%) was found with the VV-A80V genotype. The genotype frequencies depending on the group were: YY-Y7F – 88.0...95.4%, YF-Y7F – 4.6...12.0%; RR-R25C – 4.8...43.5 %, RC-R25C – 35.9...38.0 %, CC-R25C – 20.6...35.2 %; AA-A80V – 88.0...96.2 % and AV-A80V – 3.8...11.3%; alleles: Y – 0.94...0.98; F – 0.02...0.06; R and C – 0.39...0.61 each; A – 0.94...0.98, V – 0.02...0.06. A shift in genetic equilibrium at the R25C locus was observed in the groups of cows and heifers (p < 0.001). Between 2016 and 2021, the frequencies of the F-Y7F, V-A80V (from 0.06 to 0.02), and C-R25C (from 0.61 to 0.39) alleles decreased. Cows of the CC-R25C genotype exceeded their RR- and RC-matched counterparts in terms of live weight at the time of insemination (by 17.03–22.94 kg) and the proportion of infertile cows (by 1.06–4.47 %). The lowest calf yield was recorded from cows with the YF-Y7F (80.0 %), RC-R25C (90.5 %), and AA-A80V (92.7 %) genotypes. No significant impact of polymorphisms on the quality of offspring has been identified. Heterozygous heifers outperformed homozygous ones for the Y-Y7F, A-A80V, and R-R25C alleles by 30.23–42.04 kg, 43.33–83.28 kg, and 15.50–30.72 kg (p < 0.05), respectively. Calves were weaned from their mothers of YF-Y7F, CC-R25C and AV-A80V genotypes 3.6...12.7 days earlier than the analogues (p<0.05 for Y7F and A80V). Studying the leptin gene in a larger and more diverse sample of animals is promising for selecting cattle based on fattening performance and herd well-being.