Polymorphisms in the transforming growth factor β3 gene and their associations with feed efficiency in chickens

Growth and feeding traits such as BW, BW gain (BWG), feed intake (FI), and feed conversion ratio (FCR) are of economic importance in poultry production. In this study, 8 SNP of the transforming growth factor β3 (TGF-β3) gene, which are located in the proximity of quantitative trait loci affecting BW and FCR, were selected to be genotyped by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry in 2 yellow meat-type chicken populations with 724 birds in total. Body weights at 49 (BW49) and 70 (BW70) d of age and FI in the interval were recorded, and respective BWG and FCR were calculated for each bird. Two SNP with a very low minor allele frequency (<1%) were discarded from further analysis. The results showed that both rs13586818 and rs14535174 had significant effects (P < 0.05) on BWG and FCR, and that rs14535177 was significantly (P < 0.05) associated with BW49, BW70, and FI. Furthermore, birds with the GA genotype of rs13586818 showed strongly higher FCR and lower BWG (P < 0.05) compared with AA individuals. The TT birds had significantly larger BWG (P < 0.05) than GT birds in rs14535174, whereas FCR was the opposite. Individuals with the GC genotype of rs14535177 had significantly higher BW49, BW70, FCR, and FI (P < 0.05) than those with the GG genotype. Additionally, haplotypes based on 3 SNP of rs13586818, rs14535174, and rs14535177 were significantly associated with FCR (P < 0.05). The SNP and analyzed haplotypes identified in this study might be used as potential genetic markers in meat-type chicken breeding.