POLYMORPHISM OF PRL, ß-LG AND LEP GENES IN DAGESTAN MOUNTAIN SHEEP AND THEIR CROSSBREEDS

Abstract

Determining the frequency of alleles and genotypes of genes affecting lactation activity and milk composition makes it possible to identify informative markers for
breeding programs. The aim of the research was to study the polymorphism of the PRL (prolactin), β-LG (β-lactoglobulin), and LEP (leptin) genes in Dagestan Mountain sheep and their
crossbreeds with the Lacaune breed. The research was carried out in 2025 at the Laboratory of
Advanced Dairy Resources and the Department of Genetics and Biotechnology of the AllRussian Research Institute of Sheep and Goat Breeding – a branch of the FSBSI “North Caucasus Federal Agricultural Research Center” (Stavropol Territory). The study included 100
animals, 40 of which belonged to the Dagestan Mountain breed and 60 were crossbreeds.
Genotyping was performed using the PCR-RFLP method with specific primers and restriction
endonucleases. It was found that in purebred animals, allele B of the PRL gene (91.3%) and
allele G of the LEP gene (96.3%) predominated, indicating a low level of polymorphism. The
β-LG gene showed a more balanced allele distribution (A – 36,3%, B – 63,8%) and a high
level of expected heterozygosity (He = 46.2%). In crossbred animals, the frequency of the T
allele of the LEP gene increased (15,0% versus 3,8% in purebred ones), accompanied by an
increase in the number of effective alleles (Ae = 1,30) and expected heterozygosity (He =
26,0%). The obtained data reflect the genetic structure characteristics of purebred and crossbred animals. Further research should be focused on confirming the associations of the identified genotypes with economic traits and assessing their influence on qualitative milk composition.