Association Analysis of the FTO Gene Polymorphisms with Growth and Carcass Traits of Heying Black Chicken and Tissue Expression Profile

Fat volume and obesity-related genes (e.g., the FTO gene) are important candidate genes affecting energy metabolism. Single nucleotide polymorphisms (SNPs) in the FTO gene are associated with carcass, growth and meat quality traits of pigs, cattle, sheep, rabbits and ducks. The purpose of this study was to detect the single nucleotide polymorphisms in the chicken FTO gene coding region by DNA sequencing and analyze its association with the carcass and growth traits of Heying black chickens. We detected polymorphisms in exons 5, 7, 8 and 9, respectively, g.57337C>A, g.64757T>G, g.97213G>A and g.220985G>A, which are synonymous mutations. g.57337C>A mutation site CA and AA genotype individuals were significantly higher than CC genotype individuals in live weights, head weights, breast muscle weights and leg muscle weights (p < 0.05), AA genotype individuals were significantly higher than CC genotype individuals in slaughter live weights and liver weights (p < 0.05) and CA and AA genotype individuals were significantly higher than CC genotype individuals in heart weights (p < 0.01). In terms of growth traits, the weights of individuals with genotype CA at 8 weeks were significantly higher than that of individuals with genotype CC (p < 0.05), and the weights of individuals with genotype AA and CA at 10 weeks and 16 weeks were significantly higher than that of individuals with genotype CC (p < 0.05). For the g.64757T > G mutation, individuals with the TT genotype exhibited significantly higher values (p < 0.05) than those with the TG genotype across multiple traits, including slaughter weight, live weight, eviscerated weight and semi-eviscerated weight. Individuals with GG genotypes were significantly higher than individuals with TG genotypes (p < 0.05) in slaughter weights and wing weights. In terms of growth traits, the 16-week-old body weight of individuals with TT genotype was significantly higher than that of individuals with TG genotype (p < 0.01). The GA genotype exhibited significantly higher slaughter weights in the g.97213G>A variant compared to the GG genotype (p < 0.01), and in live weights, eviscerated weights, semi-eviscerated weights, leg muscle weights and wing weights, GA genotype was significantly higher than in GG genotype (p < 0.05). In terms of growth traits, GA genotype was significantly higher in individuals 8 weeks old, 10 weeks old and 16 weeks old than GG genotype (p < 0.05). g.220985G>A was significantly higher in individuals with GG genotype than GA genotype (p < 0.05). In terms of growth traits, the weight of GG genotype was significantly higher than that of GA genotype (p < 0.05). The results showed that the FTO gene may be a candidate gene related to chicken growth and slaughter traits and lays a foundation for Heying black chicken assisted breeding.