Genotype × environment interaction for growth traits of Nile tilapia in biofloc technology, recirculating water and Cage systems

An assessment was made on the genotype-environment interactions affecting growth traits of Nile tilapia (Oreochromis niloticus) reared in recirculating water (RAS), biofloc technology (BFT) and Cage systems. Weight data collected at 56 (W56) and 168 (W168) days of age came from a study designed with 86 full-sib families originating from 43 sires and 86 dams. All animals were raised in RAS until reaching approximately 56days of age. After that, they were distributed among the three systems evaluated. Variance in W168 was higher in the RAS group, when compared to BFT and cage groups. Posterior means (highest posterior density interval with 95% of samples) of heritability in groups W56, W168 BFT, W168 RAS and W168 Cage were 0.84 (0.77; 0.91), 0.82 (0.73; 0.94), 0.62 (0.53; 0.72) and 0.78 (0.67; 0.88), respectively. Posterior means of genetic correlation (highest posterior density interval with 95% of samples) between W168BFT and W168 RAS, W168BFT and W168 Cage, and W168 RAS vs W168 Cage were 0.99 (0.98; 1.00), 0.83 (0.75; 0.89), and 0.88 (0.83; 0.93), respectively. Posterior means (highest posterior density interval with 95% of samples) of expected response concerning direct selection in groups W168 BFT, W168 RAS and W168 Cage were 87.14 (73.61; 102.64), 98.74 (82.12; 114.98) and 74.23 (60.95; 87.79) grams/generation, respectively. Expected response concerning indirect selection of W168 was similar to direct response. Heritability of W168 depends on farming system but is high; therefore it is safe to say that genetic progress is obtainable through selection. Variance in W168 is subject to the environment. It is unnecessary to develop environment-specific breeding programs aiming for higher weight at 168days of age of Nile tilapia reared in recirculating water, biofloc and Cage systems.