This study aimed to estimate the variance components of growth traits in white-feathered broilers under different environments and detect the genotype-by-environment interaction (G × E) effects of the same trait across various environments. Using growth performance records of white-feathered broilers from 6 batches under 3 environments, five key growth traits were analyzed: 45-day weight (45DW), weight gain (WG), feed conversion ratio (FCR), feed intake (FI), and mid-term metabolic weight (MWT), encompassing a total of 8,651 phenotypic records. Detailed quality control and grouping were performed on the original phenotypic data. Subsequently, variance components analysis of the five growth traits across the three feeding environments with different energy and protein levels was conducted using the mixed linear model in SPSS software. The genetic correlations of the same trait between different environments were then estimated using the multi-trait animal model in ASReml software as indicators for detecting G × E effects. The results showed that the established quality control criteria effectively eliminated abnormally distributed phenotypic values. In the variance components analysis, the genotype-by-environment interaction (G × E) effects had extremely significant impacts on all growth traits. These effects not only altered broiler growth performance due to variations in feeding environments with different energy and protein levels but also stemmed from differences in environmental adaptability among different families. The bivariate model revealed the strongest G × E effects between breeder feed and high-energy broiler feed, followed by those between low-energy broiler feed and the other two feeds, with most G × E effects being significant. In conclusion, the genetic performance of the same growth trait varied across different feeding environments, and significant G × E effects existed between some feeding environments. Therefore, environmental differences and G × E effects on genetic progress should be considered when conducting genetic improvement of growth traits in white-feathered broilers.
Zhao et al. (Sun,) studied this question.