Parâmetros genéticos para peso corporal, rendimento de carcaça e características morfométricas em tilápias do Nilo (Oreochromis niloticus) em diferentes idades padrão

Abstract

Tilapias are the second more reared group of fish in the world and Nile tilapia is it leading representative. Growing has been the main goal of the few existing selection programs. However, carcass yield (CY) is important for the economic efficiency development of this species production chain. The use of indirect selection for CY is interesting, because mass selection is impracticable since data collection is only possible after slaughter. The aim at this work was to estimate genetic parameters and correlation between body weight (BW), CY, height (H), width (W) and corrected length (CL) as functions of standard ages in Nile tilapia, Chitralada strain, reared in recirculation system. Bivariate animal model analyses were carried for all traits in five standard ages (119, 147, 175, 203 and 231 days) and 16 distinct models for fixed and random effects were compared. Data from 2042 tilapias were used for 560 bivariate analyses. Heritability (h2) estimates through all ages vary from 0.20 to 0.94 for CY, 0.20 to 0.44 for BW, 0.21 to 0.40 for H, 0.13 to 0.80 for W and 0.18 to 0.48 for CL. All genetic correlation estimates were positive. The genetic correlations between BW and morphometric traits (0.66-1.00) at all ages, CY and H (0.71) at 119 days and CY and CL (0.58) at 231 days were high. The results for h2 highlight the possibility to achieve high genetic gains due selection for any of those traits. The correlations shows the possibility to achieve indirect genetic gains for CY and BW by selecting other traits, highlights for H at 119 days and CL at 231 days of standard age.