The objective of our analyses was to identify prolactin gene polymorphism and determine its effect on reproduction traits in sows. The research included 138 Polish Large White sows from four nucleus herds supervised by the Polish Pig Breeders and Producers Association “POLSUS” based in the kujawsko-pomorskie province. Molecular analyses were conducted using the PCR-RFLP method. Three PRL/TaaI genotypes and two alleles were found in the examined sows. The allele frequency was as follows: PRLIns – 0.50; PRLDel – 0.50, and the genotype frequency was at the following level: Del/Del – 0.27, Ins/Del – 0.45, Ins/Ins – 0.28. We determined the mean age at the first farrowing, and the mean number of piglets born alive and reared until 21 of their lives in two subsequent farrows. No statistically significant differences were found between the genotype variants within the analysed reproduction traits in Polish Large White pigs. The results we obtained prove that there is a need to continue research in this area using a larger group of animals.
