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 conver-sion ratio (FCR) are of economic importance in poultry production. In this study, 8 SNP of the transforming growth factor 33 (TGF-/Â3) 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 re-sults showed that both rsl3586818 and rsl4535174 had significant effects (P <0.05) on BWG and FCR, and that rsl4535177 was significantly (P <0.05) associ-ated with BW49, BW70, and FI. Furthermore, birds with the GA genotype of rsl3586818 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 rsl4535174, whereas FCR was the opposite. Individuals with the GC geno-type of rsl4535177 had significantly higher BW49, BW70, FCR, and FI (P <0.05) than those with the GG genotype. Additionally, liaplotypes based on 3 SNP of rsl3586818, rsl4535174, and rsl4535177 were signifi-cantly 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. [ABSTRACT FROM AUTHOR]