Do gene polymorphisms associated with feed efficiency influence production traits and ascites incidence in broiler crosses

Single nucleotide polymorphisms in UCP, POMC, MC4R, and MC3R were identified and associated with feed efficiency in a single commercial broiler pedigree line. The ascites susceptible and resistant lines were found to differ in allele frequencies for these SNPs as well as ascites mortality, growth, body weight, breast yield, and FCR. Therefore it was hypothesized that these SNPs may be associated with the observed differences in these lines. Therefore these SNPs were investigated in F2 progeny derived from crosses of the ascites susceptible and resistant lines.; The POMC Leu haplotype is associated with increased BW on Days 0 and 7, with no significant differences observed past Day 7 for any of the POMC haplotypes. The POMC Leu haplotype is also associated with increased absolute and relative Pectoralis major on Day 56, which could have possible economic implications for the broiler industry. The MC4R Leu haplotype is associated with decreased BW from Days 28 to 49, but experiences an increased rate of growth from Days 49 to 56 such that no significant differences were observed for Day 56 BW for any of the MC4R haplotypes. No significant differences were observed for any of the MC4R haplotypes for absolute or relative Pectoralis major. No significant differences were observed for any BW or meat yield parameter for the MC3RGly104Ser polymorphism, although no birds were genotyped as homozygous MC3R Ser in this study. For the MC3RMet54Leu polymorphism, the MC3R Leu haplotype was associated with increased BW from Days 42 to 56. This increase in BW was due to a proportionate increase in absolute weights of Pectoralis major, wings, thighs, drums, and total gut as compared to the MC3R Met and Met-Leu haplotypes. This increase in absolute Pectoralis major could have economic implications for the broiler industry.; For ascites mortality no significant differences were observed for any of the polymorphisms investigated, however it appears that the MC4R Leu polymorphism is associated with increased ascites mortality. Although more research is needed to further elucidate this relationship. Overall that inclusion of some of these SNPs into a breeding program may provide economic benefits specifically in Pectoralis yield.