PCR RFLP revealed a wide variation in the level of alleles and genotypes of ESR gene in all 11 studied populations of pigs of Large white breed contained in the Ukraine and Belarus. The vast majority of the populations studied is characterized by high fever actual (H0) heterozygosity than expected theoretically. Found differences in allele frequencies and genotype ESR genes between different groups of animals, even within the same industry. In four investigated Belarus pigs populations ESR gene generally have a wide span of frequencies of allele B (from 0,08 ± 0,026 to 0,40 ± 0,085 boars, 0,179 ± 0,024 - 0,500 ± 0,014 in sows, 0,143 ± 0,027 - 0,614 ± 0,023 of replacement chickens). Seven of the populations of pigs in Ukraine identified the following allele frequencies in - 0,15 ± 0,027 - 0,568 ± 0,025 in breeding sows, 0,500 ± 0,026 - 0,58 ± 0,029 - in the commercial farms on average per herd.
Large white swine population polymorphism by estrogen receptor gene in Ukraine and Belarus