Studies On The Relationships Between Polymorphisms Of Sows' Locus For ESR,OB Gene And Their Reprduction Traits

In this experiment. Estrogen receptor (ESR) gene and Obesity (OB) gene polymorphisms were detected by methods of PCR-RFLP and Bi-PASA in five breeds, which were Jiangquhai, Xiaomeishan, Erhualian, Landrance and Large White. We also analyzed the corelation between litter size, birth weight, 20d weight, teat number and the two genes.According to the population genetic structure, B allele frequencies of ESR were higher in domestic breeds than in foreign breeds. Chi-square (X2) test demonstrated that ESR locus were in Hardy-Wenberg equilibrium in the populations of Xiaomeishan, Landrance and Large White (P>0.05), but not in Jiangquhai and Erhualian (P<0.05).As to the OB gene, there was only TG and GG genotypes but no homozygous TT, in the population of Landrance and Large White, but all the three genotypes were found in the other three domestic breeds. Chi-square (X2) test showed that OB locus were in Hardy-Wenberg equilibrium in the populations of Xiaomeishan, Jiangquhai and Erhualian (P>0.05), but not in Landrance and Large Write (P<0.05).Average litter size differed significanfly within different ESR genotypes, TNB and NBA of BB genotype were 2.27 andl.95 more than those of AA genotype in first parities. In latter parities, the figers were 1.29 and 1.36,conrespondly. The additive effects per B allele worked towards TNB and NBA were 1.14(0.64) and 0.97(0.68)pigs/litter in frist parity (later parities), respectively. The dominance effects were 0.24(0.50) pigs and 0.20(0.49) pigs for TNB and NBA, in first parity (later parities), respectively.The results indicated that ESR gene affects litter size in an additive-dominant genetic model. And ESR gene produced no bad effect on birth weight. 20d weight and test number in sows.The effect of OB genotypes on litter size was detected. The results show means of litter size in frist party -. later parties and the highest litter size had significant difference between TG genotype sows and TT > GG genotypes sows (P<0.05), but not between TT genotype sows and GG genotype sows (P>0.05). The results indicated that OB gene affects litter size in a dominant genetic model.As to the OB gene, the difference of means birth weight and 20d weigth between TT genotype sows and GG, GT genotypes sows were significant (P<0.05), while nosignificant diffenece existed between TG genotype sows and GG genotype sows (P> 0.05). The birth weigth and 20d weight were incresed per T favorable allel of OB with additive effects of 0.082 and 0.28Kg, respectively. Dominance effects were -0.014 and -0.09 Kg. The results showed that OB gene affects birth weigth and 20d weight in an additive genetic model. The corelation between OB gene and teat number was also detected, no significant difference among genotypes was found.Counclusions drawn form this research illustrated that, marker-assisted selection(MAS) using ESR and OB gene are increase litter size and will be of considerable economic value to pork producers. In swine population, magnitude of population performance could increase obviously with B allele of ESR gene and T allele of OB gene freqncy accumulating.