Genetic Variants of Insulin-Like Growth Factor 1 (IGF-1) Gene and Their Relationship with Productive Traits in Ross 308 Broilers

Abstract

This study aimed to investigate the relationship between different genetic variants of the insulin-like growth factor 1 IGF-1 gene and some productive traits in Ross 308 broilers. A total of 150 one-day-old chicks were reared under good management conditions based on the rearing guide and a free-range feeding system. The birds were numbered, and their weights were recorded weekly to calculate weekly weight gain. Other weekly body measurements were also taken. After the rearing period, blood samples were collected from the birds via the wing vein, followed by slaughter and weighing of the carcass to determine the dressing percentage. The main and secondary cuts were weighed, and chest dimensions were measured. DNA was extracted, and three genetic structures were identified using sequencing technology, including GG, GT, and TT, with genetic structure proportions of 0.34, 0.58, and 0.08, respectively. The allele frequencies of G and T were 0.63 and 0.37, respectively. The results showed a significant superiority (P≤0.05) in weight and weekly weight gain for the TT genetic variant in the third, fourth, and fifth weeks compared to the other genetic variants (GT and GG). The TT variant also exhibited superiority in chest circumference in the third and fifth weeks and chest width in the third week. On the other hand, the TT and GG genetic variants showed superiority in chest width in the second and fourth weeks. The TT variant also demonstrated superiority in carcass weight and chest length compared to the other genetic variants. Moreover, the study revealed a significant increase (P≤0.05) in the dressing percentage, relative weight of the chest, wings, and back for the GT and GG genetic variants compared to the TT genetic variant. The GT variant also showed superiority in the relative weight of the thighs. However, there were no significant differences among the genetic variants in the relative weight of the neck and chest depth.