Genetic improvement of local chicken breeds is crucial and can be accelerated using modern breeding ap-proaches, such as marker-assisted selection. Therefore, there is a need to identify diverse markers associ-ated with different traits. This study aimed to investigate the association between two mutations located in the IGF1 and TGFβ1 genes in two selected local chicken lines over two generations. Lines were normally feathered, CE1, and naked-neck, CE3, and both lines were selected for growth traits for 10 generations be-fore the current study. Chickens were genotyped using the PCR-RFLP approach. The results revealed that the IGF1 mutation was consistently associated with lower body weight at six weeks of age and body weight gain in both lines over the two generations, with significant negative additive genetic effects for the two traits. However, the TGFβ1 mutation was consistently associated with body weight at four and six weeks of age, as well as body weight gain in CE1 in both generations, and was associated with body weight at six weeks of age and body weight gain in CE3 in both generations. The results indicate the negative effects of the two mutations on growth traits in selected chickens, and therefore, the normal genotypes may be used as potential candidate markers for growth in local chickens.
Orabi et al. (2025) studied this question.