Genetic variability in the ESR locus in pigs of the Landrace and Large White breeds kept in the Czech Republic

The estrogen receptor (ESR) gene is a genetic marker for reproductive traits in sows. In LW breed, ESR-PvuII polymorphism is associated with litter size. ESR-PvuII variability in Landrace (L) breed has not yet been described in literature and in the Czech Republic there are no available data on Large White (LW) breed. In this study, ESR-D allele frequency ESR-D = 0.10 was found in sows of the L breed (284 animals) and the variability on four breeding farms ranged from 0.02 to 0.13. In sows of the LW breed (539 animals) the ESR-D frequency was ESR-D = 0.35. Variability in representation of D allele in the framework of nine observed breeding farms ranged from 0.18 to 0.50.