PSVIII-29 Analysis of genotype by environment interaction across time for Nile tilapia reared in different production systems

Abstract

Abstract Nile tilapia is the second most important freshwater fish for human consumption worldwide and it is produced under many different conditions. Even though genotype by environment interaction (GEI) can arise due to many factors, most studies with tilapia have focused on water quality on pond and cage systems. Therefore, the objective of the current work was to evaluate GEI on body weight (BW) of Nile tilapia raised in biofloc technology (BFT), Cage, and recirculation aquaculture systems (RAS) from 100 to 350 days of age. A Bayesian multi-trait random regression model (MTRRM) with age as random regression covariable was employed to evaluate the temporal trend of GEI. Estimated genetic correlations between BFT and RAS were above 0.7 for almost any combination of ages evaluated (Figure 1). However, genetic correlations between Cage at ages below 150 days with either BFT or RAS at any other age were positive but below 0.5. The posterior means of heritability for BW were found to reach peaks of 0.40, 0.38 and 0.29 around 230 days for RAS, BFT, and Cage respectively (Figure 2). Conversely, the ratio between common family environment and phenotypic variances presented an overall decreasing trend with minimums around 0.22, 0.15 and 0.10 at 230 days for Cage, RAS, and BFT, respectively. The MTRRM has shown to be a powerful statistical tool to assess changes across time for genetic parameters of interest. In conclusion, GEI was found to be dynamic across time, with stronger effects between Cage and both BFT and RAS if selection is promoted prior to 150 days. However, GEI is negligible for most of the situations considered if selection is performed after 200 days of age in either BTF or RAS, with the possibility of achieving better indirect selection results if selection is performed around 230 days.