ESR基因多态性对不同胎次的大白猪母猪产活仔数的影响

为了研究ESR基因对大白猪经产母猪整个生产周期的影响并应用于猪繁殖性状改良，试验检测了该基因在472头大白猪经产母猪中的多态性分布，并根据基因分型结果分析了不同基因型对该群体1774胎产活仔数的影响。结果表明，AA、AB、BB基因型频率为0.206、0.572、0.222，AB基因型为优势基因型；A、B基因频率为0.493、0.507，B等位基因为优势等位基因。通过对不同胎次的分析发现，头胎AB基因型个体的产活仔数高于AA、BB基因型个体；2胎BB基因型个体的产活仔数高于AA、AB基因型个体；3胎AB、BB基因型个体的产活仔数高于AA基因型个体；4～7胎AA基因型个体的产活仔数最多（5胎除外），8胎及以上胎次AB基因型个体的产活仔数最多，呈现一定的规律性，但是各胎次内的差异均不显著。

Polymorphism of the ESR Gene and its Association with the NBA Trait in Different Parities in Large White

In order to study the genetic effect of the ESR gene in the whole production cycle of Large white，the polymorphism of ESR in 472 sows were detected, the association between 1774 litters record on litter size and genetic effect were analysised. The results showed that the frequency of AA, AB and BB genetypes were 0.206, 0.572 and 0.222, the AB genetype with the highest frequency; the B allele of ESR gene with the frequency 0.507 was higher than A allele with the frequency 0.493. Through analysis of different parities, the AB genotype had much higher number of born alive than AA and BB genotypes at the first parity, the BB genotype had much higher number of born alive than AA and AB genotypes at the second parity, the AB and BB genotypes had much higher number of born alive than AA genotype at the third parity, the AA genotype with the highest number of born alive at the forth to the seventh parities except for the fifth parity，the AB genotype with the highest number of born alive at the rest parities the AA later parities and all of the parities，showing a certain regularity, but with no significance in all of the parities.