Allele frequency for c.335 A>C polymorphisms in porcine ghrelin/obestatin prepropeptide gene and association analysis with performance traits in various pig breeds

The allelic frequency of c.335A>C polymorphisms in the porcine ghrelin/obestatin prepropeptide (GHRL) gene was surveyed among six pig breeds and two subspecies of wild boars. The c.335C was the most frequent allele in Berkshire, Landrace, Large White, Yorkshire, and Clawn miniature pigs and Ryukyu wild boars (Sus scrofa riukiuanus), whereas c.335A was the most frequent allele in Duroc and Meishan pigs and Japanese wild boars (S. s. leucomystax). The association of c.335A>C with performance traits was analyzed in Duroc, Landrace, Large White, and (Landrace × Large White) × Duroc (LWD) cross-bred pigs. No associations between c.335A>C genotype and average daily weight gain, backfat thickness, or intramuscular fat were detected. However, an association was observed between loin eye muscle area (EMA) and c.335A>C genotype in Duroc gilts. The AA genotype group had larger EMA than the AC genotype group in Duroc gilts; however, this association was not significant in Duroc boars and barrows or the other pig populations investigated. These results demonstrate that GHRL c.335A>C is not a major quantitative trait loci candidate on pig chromosome 13 affecting fat deposition.