Microenvironmental sensitivity of body weight at harvest in Nile tilapia: Genetic parameters, performance test traits, and genetic variability

Abstract

Uniformity of body weight at harvest is a trait of great economic importance in Nile tilapia production. Studying the genetic aspects of microenvironment sensitivity proves to be a valuable instrument for enhancing the uniformity of production. The microenvironmental sensitivity of a given genotype can be quantified by analyzing the degree of genetic heterogeneity of environmental variance. This study involved the analysis of a database comprising phenotypic records of body weight at harvest for 10,207 individuals. It aimed to estimate genetic parameters, scrutinize the effects of direct selection, and evaluate how selection impacts the genetic variability within a Nile tilapia breeding program. Estimates of genetic parameters were obtained by Bayesian procedures using a two-step animal model in GIBBS1F90 (BLUPF90 family) software. The coefficients of variation for residual variance (0.29) and genetic correlation (−0.43) between body weight at harvest and microenvironmental sensitivity were deemed moderately favorable. Direct selection for microenvironmental sensitivity resulted in a 41% increase in the coancestry coefficient. The group chosen for low microenvironmental sensitivity exhibited a significant difference of 19.08% in the coefficient of variation from the group selected for high microenvironmental sensitivity. No significant differences in the coefficient of variation were observed between tilapia of the commercial line selected for growth rate and those selected for low microenvironmental sensitivity. Selection for microenvironmental sensitivity has the potential to enhance production uniformity. Significantly, directional breeding for performance achieves a comparable improvement in uniformity. Nevertheless, opting for direct selection for microenvironmental sensitivity could result in a decrease in genetic variability within Nile tilapia breeding programs.