347GENETIC EFFECT OF ESR GENE ON REPRODUCTIVE TRAITS IN BREEDING PIGS FROM TAIWANESR has beneficial effects on the reproductive performance, such as TNB, NBA of sows. Then, our aim was to investigate the polymorphism of Pvu II sites of ESR gene in Yorkshire, Landrace and Duroc populations from Taiwan to verify the association between ESR gene mutation and reproductive traits. The results showed that the polymorphic sites of ESR gene were found in three breeds, but BB genotype was not detected in Duroc; The results of χ2 test indicated that these sites in three populations fitted Hardy-Weinberg equilibrium; AA genotype was the dominant genotype in Landrace and Duroc, while the genotype AB was dominant genotype in Yorkshire; The genotype distribution was significantly different among Yorkshire and other two pig breeds (P < 0.01), but was not significantly different between Landrace and Duroc; The PIC values of Yorkshire and Landrace were above 0.25, which displayed moderate polymorphism. PIC values of Duroc were 0.18, which displayed light polymorphism; Weaning survival rate of primiparous sows with genotype AB and BB were significantly higher than that of individuals with genotype AA (P < 0.05). The BWL of individuals with genotype AB was significantly higher than that of individuals with genotype BB. In multiparous sows, all genotypes of ESR gene showed no significant influence on the reproductive traits.wbbao@yzu.edu.cnResearch5112015ESR gene,Pig,Polymorphism,PolymorphismWenhua Dong, Riwei Xia,Li Sun,Yongjiu Huo,Hongqing Cheng,Wenbin Bao,Shenglong Wu College of Animal Science and Technology, Key Laboratory for Animal Genetics, Breeding, Reproduction and Molecular Design of Jiangsu Province, Yangzhou University, Yangzhou 225009, China., College of Animal Science and Technology, Key Laboratory for Animal Genetics, Breeding, Reproduction and Molecular Design of Jiangsu Province, Yangzhou University, Yangzhou 225009, China., College of Animal Science and Technology, Key Laboratory for Animal Genetics, Breeding, Reproduction and Molecular Design of Jiangsu Province, Yangzhou University, Yangzhou 225009, China., College of Animal Science and Technology, Key Laboratory for Animal Genetics, Breeding, Reproduction and Molecular Design of Jiangsu Province, Yangzhou University, Yangzhou 225009, China.,Yangzhou Engineering Research Centre for Breeding of Breeder Pig, Yangzhou 225009, China., College of Animal Science and Technology, Key Laboratory for Animal Genetics, Breeding, Reproduction and Molecular Design of Jiangsu Province, Yangzhou University, Yangzhou 2250