Study On Selection Of Prolific Large White Pigs Using Marker-assisted Best Linear Unbiased Prediction

The litter size is one of important components for sow reproductive trait. Increasing the litter size can significantly improve production efficiency and economic benefit. Direct selection can’t improve reproductive trait of pig due to its sex-limited nature, low heritability and being effected largely by the environmental factors. With the development of molecular biology, bioinformatics and other emerging disciplines, using marker-assisted selection can successfully solve this problem. To select new Large White line with high number of piglets born, genotypes of four candidate major genes, ESR, FSHβ, CTNNAL1, mi R-27 a were tested in 472 Large White sows from Xi Hu Zhou company in Wuhan. The ESR, FSHβ, CTNNAL1 and mi R-27 a locus showed different polymorphism in the Large White population. The correlation between different genotypes and reproductive traits was also studied in this paper. The mainly results were as follows:The ESR, mi R-27 a, FSHβ locus showed that the frequencies of allele A were 0.58, 0.80 and 0.16, respectively. The CTNNAL1 locus showed that the frequencies of allele G were 0.64.Through analyzing associations of four candidate genes with reproductive traits in Large White population, we found: the first-born total number born of the BB genotype is 0.72(P<0.05) more than the AA genotype in ESR gene. In FSHβ gene, the first-born total number born of the BB genotype is 1.81(P<0.05) more than the AA genotype; the all-parity total number born of the BB genotype is 1.25(P<0.05) more than the AA genotype and the additive effect is 0.48 pigs per litter; the all-parity number born alive of the AB, BB genotypes is 1.36(P<0.05), 1.49(P<0.05) more than the AA genotype respectively and the additive effect is 0.65(P<0.05). In CTNNAL1 gene, the multiparous total number born of the CG genotype is 0.55(P<0.05) more than GG genotype and the additive effect is 0.27(P<0.05) pigs per litter; the all-parity total number born of the CG genotype is 0.50(P<0.05) more than GG genotype; the all-parity number born alive of the GG genotype is 0.55(P<0.05) more than CC genotype and the additive effect is 0.18(P<0.05) pigs per litter. The mi R-27 a gene have not dramaticlly influence on the litter size trait.Through analyzing associations of the combined genotypes of four candidate genes with reproductive traits in Large White population, we found: the optimal combined genotype of ESR, CTNNAL1 genes is AABB; the optimal combined genotype of ESR, CTNNAL1 genes is AACG; the optimal combined genotype of ESR, mi R-27 a genes is AAAA; the optimal combined genotype of FSHβ, CTNNAL1 genes is BBCG; the optimal combined genotype of FSHβ, mi R-27 a genes is BBAB; the optimal combined genotype of CTNNAL1, mi R-27 a genes is CGAA.Through analyzing associations of the EBVs of four candidate genes with reproductive traits in Large White population, we found: the B allele of ESR gene is favorable allele and may have the potential to increase the first-born total number born EBVs, the multiparous number of born alive EBVs and decrease the first-born number of stillbirth EBVs, the first-born number of mummy EBVs; the B allele of FSHβ gene is favorable allele and may have the potential to increase the first-born total number born EBVs, the multiparous number born alive EBVs, the number of weaned EBVs and decrease the multiparous number of mummy EBVs; the G allele of CTNNAL1 gene is favorable allele and may have the potential to increase the first-born total number born EBV, the multiparous number born alive EBVs, litter birth weight EBVs and decrease the first-born number of stillbirth EBVs; the G allele of mi R-27 a gene is favorable allele and may have the potential to increase the multiparous total number born EBVs, all parity total number born EBVs, litter birth weight EBVs and decrease the first-born number of stillbirth EBVs.