Genetic effect and combined genotype effect of ESR , FSH β, CTNNAL1 and miR-27a loci on litter size in a Large White population.

To select new Large White line with high number of piglets born, genotypes of estrogen receptor (ESR), the follicle stimulating hormone b subunit (FSHb), catenin alpha like 1 (CTNNAL1) and miR-27a were tested in 472 Large White sows. The associations of different genotypes with litter size traits were also studied. The results showed ESRBB and FSH beta(BB) sows produced 0.41-1.49 more pigs per litter (p<.05) for total number born (TNB) and number born alive (NBA) than did other corresponding genotypes. TNB of CTNNAL1(CG) sows is 0.50 more pigs per litter (p<.05) than that of CTNNAL1(GG) sows with the dominance effect of 0.25 pigs per litter (p<.05). miR-27aBB sows had a less estimated breeding value (EBV) to TNB and had a more number of mummified pigs (NM) than did miR-27aAA or miR27aAB sows (p<.05). Therefore, ESRB, FSH beta(B), CTNNAL1(G), miR-27a(A) allele was favorable for litter size traits. Furthermore, combined genetic effect analysis showed ESRAAFSH beta(BB), ESRAACTNNAL1(CG), ESR(AA)miR-27a(AA), FSH beta(BB)CTNNAL1(CC), FSH beta(BB)miR-27a(AA) and CTNNAL1(CG) miR-27a(AB) was the favorable combined genotype for litter size traits. These results identified favorable alleles and genotypes for litter size traits and suggested a potential selection scheme for litter size in Large White pigs.