Study On Polymorphisms Of Estrogen Receptor Gene And Its Relationship With Reproduction And Growth Traits Of Foreign Pigs In Sichuan Province

We investigated the Pvu II Polymorphisms of ESR gene and the frequencies of gene and genotype in Sichuan Yorkshire, Landrace and Duroc sow herds by use of PCR-RFLPs, and we also studied the effect of the estrogen receptor (ESR) gene on reproduction and growth traits in these three breeds. Results showed that the frequencies of allele B in Yorkshire, Landrace and Duroc were 0.4706> 0.3855 and 0.4643, respectively. Genotype frequencies had no significant difference in these three breeds (P > 0.05) by the use of x 2 test.In the analysis of the correlation between ESR gene and the reproduction and growth traits by using the data of these three breeds respectively, there was an inclination of BB>AB>AA in the TNB and NBA and the two traits had general detectable difference among three breed sows with different genotypes in first and latter parities (P<0.05). Especially in first parity of Duroc and latter parities of Landrace sow herds, TNB had significant difference between these three genotypes (P<0.01). In Sichuan Yorkshire, Landrace and Duroc sow herds the TNB and NBA were increased per allele B of ESR with additive effects of 2.29 (1.28) and 1.92 (1.90), 2.7 (2.95) and 1.25 (2.01) and 3.56 (3.67) and 2.1 (2.33) pigs/litter in first parity (latter parities), respectively.In latter parities litter size of twenty days in Yorkshire and litter size of 30/45 days in Landrace had an inclination of BB>AB>AA, as well as litter size of thirty or forty days in Duroc in first and latter parities. Especially in Duroc, there was significant difference between BB and AA in litter size of 30/45 days (P<0.01).The traits of litter weight had also an inclination of BB>AB>AA in Yorkshire, Landrace and Duroc sow herds. Especially in latter parities of Duroc, the traits of litter weight had significant difference between BB and AA (P<0.01). But in Yorkshire and Landrace sow herds, the most traits of litter weight had no significant difference between these threeenotypes (P > 0.05), as well as that in first parity of Duroc.In the analysis of the correlation between ESR gene and the reproduction and the growth traits by using the data of these three breeds totally, the results showed that TNB and NBA also had the inclination of BB>AB>AA in first and latter parities. The two traits had significant difference among sows with different genotypes in first parity (P<0.01). In latter parities, TNB had significant difference between BB and AA genotype as well as between BB and AB genotype (P<0.01), and there was significant difference between BB and A A genotype in the NBA (P<0.05). TNB and NBA of the BB genotype were 5.97 and 3.72 more pigs/litter than those of AA genotype in first parity and 3.68 and 2.89 more pigs/litter than AA genotype in latter parities. The TNB and NBA were increased per allele B of ESR with additive effects of 3.68 (1.84) and 2.89 (1.44) pigs/litter in first parity (latter parities). There were no detectable effects on LWB, LS(20), LW(20), LS(30/45), LW(30/45) or LW(70) (P>0.05), but there was an inclination of the above six traits between these three genotypes that was BB>AB>AA in first and latter parities.