Effect of NLR family pyrin domain containing 9 gene polymorphism on litter size in large white pigs.

NLR family pyrin domain containing 9 ( NLRP9 ) is a mammalian reproduction-related gene. In this study, we researched the associations between polymorphisms located in the coding sequence (CDS) of the NLRP9 gene, and both the total number of piglets born per litter (TNB) and the number of piglets born alive per litter (NBA) in Canada Large White pigs (CLW). We detected a single nucleotide polymorphism (SNP) within exon 3 (g.10910C > T). The allele frequencies at the NLRP9 locus were 0.474 for the C allele and 0.526 for the T allele. Three genotypes, CC, CT, and TT, occurred with frequencies of 0.216, 0.515, and 0.269, respectively. Sows with the CC genotype had the largest TNB and NBA, sows with TT had the smallest, and those with CT were in-between. This difference was statistically significant ( p  < 0.05). Furthermore, CC females grew faster than CT or TT females, and there was a significant relationship between NLRP9 polymorphism and the average daily gain ( p  < 0.05). Here, we provide the first evidence for a novel SNP in NLRP9 associated with litter size in CLW sows, which could be used as a genetic marker to improve litter size in pig breeding and production.