Quantitative Genetic Variation and Response for Harvest Body Weight in a Selection Program for Red Tilapia ( Oreochromis spp.)

ABSTRACT Genetic variation is indispensable for both natural and artificial selection, as well as evolution, adaptation, and the long‐term success of selective breeding programs. This study attempted to scrutinise genetic variations and responses within the breeding population of red tilapia across eight generations of selection (2016–2023). A comprehensive dataset comprising 75,950 individual fish, progeny of 1203 dams and 600 sires, with recorded body weights, was analysed. Employing a restricted maximum likelihood approach within a mixed model framework, we estimated variance components and genetic responses for this trait. Our analyses revealed the sustained presence of the additive genetic component throughout the breeding program, with the heritability estimates ranging from 0.17 to 0.27 (± 0.03–0.07) for body weight. Provided with the sustained genetic variance, the selection program significantly enhanced the body weight trait, achieving an average genetic gain of 13.5% per generation (or per year). Regression analysis of estimated breeding values against the year of birth demonstrated a consistent linear genetic trend for body weight across generations, with a regression coefficient denoted as 59.9 g or 1.21 genetic standard deviation unit. In conclusion, our selective breeding program has effectively maintained both genetic variance and genetic response in the selection criterion, specifically body weight, within this closed nucleus population of red tilapia. The abundant presence of heritable genetic components for body weight suggests a continuing response of this population to future selection pressures. Genetic selection emerges as an effective and powerful mean to augment the productivity of animal populations, thereby fostering sustainable aquaculture production.