Association between Motilin Receptor Gene Haplotypes and Growth Traits in Japanese Hinai-dori Crossbred Chickens.

We previously identified quantitative trait loci (QTL) for body weight and average daily gain in a common region between ADL0198 (chr 1: 171.7 Mb) and ABR0287 (chr 1: 173.4 Mb) on chicken chromosome 1 in an F2 resource population produced by crossing low- and high-growth lines of the Hinai-dori breed. Motilin receptor (MLNR) is a candidate gene affecting growth traits in the region. In this study, we genotyped polymorphisms of the MLNR gene and investigated its association with growth traits in a Hinai-dori F2 intercross population. All the exons of the MLNR gene in the parental population were subjected to PCR amplification, nucleotide sequenced and haplotypes identified. To distinguish resultant diplotype individuals in the F2 population, a mismatch amplification mutation assay was performed. Three haplotypes (Haplotypes 1-3) were accordingly identified. Six genotypes produced by the combination of three haplotypes (Haplotype 1, 2, and 3) were examined in order to identify associations between MLNR haplotypes and growth traits. The data showed that Haplotype 1 was superior to Haplotype 2 and 3 in body weight at 10 and 14 weeks of age, average daily gain between 4 and 10 weeks, 10 and 14 weeks, and 0 and 14 weeks of age in female in F2 females. It was concluded that MLNR is a useful marker of growth traits and could be used to develop strategies for improving growth traits in the Hinai-dori breed.