Genetic Diversity and Population Structure of the Prolactin Gene in Major Cattle Breeds of Uzbekistan
DOI:
https://doi.org/10.48165/ijapm.2026.42.02.11Keywords:
Rajasri chicks, Liquid Distillery Stillage, Growth performance, Feed intake and Feed Conversion RatioAbstract
The prolactin (PRL) gene is considered one of the major candidate genes associated with milk production and lactation performance in cattle. The present study aimed to investigate the genetic polymorphism of the PRL gene (g.8398A>G) and assess the population genetic structure of five cattle breeds raised in Uzbekistan, including Simmental, Brown Swiss, Holstein, Black-and-White, and Bushuev cattle. PRL genotypes were determined in 96 animals from each breed using allele-specific real-time PCR. The results revealed polymorphism at the PRL g.8398A>G locus in all studied populations. The frequency of the A allele ranged from 0.516 to 0.552, while the G allele frequency varied between 0.448 and 0.484. The heterozygous AG genotype was the most frequent genotype in Simmental (0.604), Holstein (0.553), Black-and-White (0.563), and Bushuev (0.542) populations, whereas a relatively balanced genotype distribution was observed in Brown Swiss cattle. Observed heterozygosity (Ho) ranged from 0.490 to 0.604, while expected heterozygosity (He) varied between 0.495 and 0.500. Nei’s genetic diversity index indicated a moderate level of genetic variation among the studied breeds (H = 0.495–0.500). Negative fixation index (FIS) values observed in most populations suggested an excess of heterozygotes and the absence of significant inbreeding. Hardy-Weinberg equilibrium analysis demonstrated that Brown Swiss, Holstein, Black-and-White, and Bushuev populations were in genetic equilibrium (P > 0.05), whereas the Simmental population deviated significantly from equilibrium (χ² = 4.71, P < 0.05), likely due to selection pressure or crossbreeding practices. Overall, the obtained results demonstrate that the PRL g.8398A>G polymorphism is highly informative and maintains considerable genetic variability in cattle populations raised in Uzbekistan. The studied locus may serve as a promising molecular marker for marker-assisted selection programs aimed at improving dairy productivity and genetic management of cattle breeds.
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