Interaction between estrogen recepto and retinol-binding protein-4 polymorphisms as a tool for the selection of prolific pigs

Abstract

The aim of the present study was to investigate the association of the estrogen receptor (ER-Pvull) and retinol-binding protein 4 (RBP4-Mspl) gene polymorphisms and their interactions with prolificacy in a commercial synthetic pig line reared in Brazil. A total of 10,374 piglet records from 218 sows and 817 litters were used for litter size analysis. Only females with three or four farrowings were included in the analysis. The mean litter size ranged from 5.0 to 19.5 piglets. DNA was extracted from leukocytes by a standard method, and ER-Pvull and RBP4-Mspl polymorphisms were characterized by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. The association between alleles or genotypes and reproductive performance was analyzed using a general linear model including the interaction between the ER-Pvull and RBP4-Mspl genotypes. For the ER-Pvull gene, the allele frequencies of allele A and allele B were 0.56 and 0.44, respectively. For the RBP4-Mspl gene, the frequencies of alleles A1 and A2 were 0.29 and 0.71, respectively. The total number of piglets born (TNB), born alive (NBA), or number of mummies and stillborn piglets (NMUM and NSB) per litter did not differ between the various ER-Pvull and RBP4-Mspl genotypes. However, when the ER-Pvull and RBP4-Mspl genotypes were considered together in each sow, TNB and NBA were 1.4 (p = 0.0026) and 0.9 (p = 0.019) higher in AA/A1 and AB/A1 animals, respectively, than in AA/A2 and BB/A1 animals. Likewise, TNB and NBA were 0.9 (p = 0.0258) and 0.8 (p = 0.0168) higher in BB/A2 and AB/A2 sows, respectively, than in AA/A2 and BB/A1 animals, but no difference was observed compared to AA/A1 and AB/A1 animals. The results showed larger litter sizes (TNB and NBA) for sows carrying the ER-Pvull allele A and the RBP4-Mspl genotype A1, and for animals carrying the ER-Pvull allele B and the RBP4-Mspl genotype A2. In conclusion, the interaction between genotypes ER-Pvull and RBP4-Mspl is more efficient in the selection of prolific sows than each one of these molecular markers alone. Copyright © 2008, Sociedade Brasileira de Genética.