Association study of an AvaI and PvuII polymorphism at the porcine estrogen receptor (ESR) gene, with litter size

A total of 144 sows housed on 3 commercial pig farms were screened for an Aval and a Pvull polymorphism in the oestrogen receptor (ESR) gene. The association between the Aval-genotype of the sows and the number of piglets born alive in the first parity was significant. Least squares means far number of piglets born alive in the first parity was 9.67 for heterozygous sows (n=35) and 8.33 for homozygous negative sows (n=105). Heterozygous sows had on average also one piglet more in second parity compared with homozygous negative sows. Data of two homozygous positive sows indicate a higher number of piglets born alive than found for the other 2 genotypes. No association was noticed between the Pvull polymorphism and the prolificacy data of the sows