Estudos genéticos longitudinais de peso, rendimento de filé e medidas morfométricas em tilápias do Nilo (Oreochromis niloticus)

Abstract

Longitudinal genetic analysis of body weight, carcass and fillet weights, fillet and carcass yields, and body measurements (heigh, width, standard length, head length and correct length), recorded from 106 to 245 days of age of Nile tilapia were performed using random regression models. The models including or not family effect, and considering homogeneity or heterogeneity of residual variance were comparede by the Bayesian information criteria (BIC). For body weight analyses, models including family effect and heterogeneity of residual variance and considering only heterogeneity of residual variance had the smallest BICs. Estimated body weigth heritability ranged from small to high, <0.10 to 0.50, for all age studied, when family effect was included in the model. The genetic correlations between body weigths at different ages were high, over 0.60. The model with the smallest BIC for fillet yield analysis included the homogeneity of residual variance. The fillet and carcass dress yield heritability ranged from moderate to high, 0.32 to 0.52, suggesting the possibility of genetic improvement for these traits. The best model for fillet yield was also used in the body measurements analyses. Heritability estimates for these traits were high, for the range of the studied ages. However, Pearson correlation between the predicted genetic values of these traits and the predicted genetic values of fillet and carcass dress yields ranged from moderate to low, <0.33, suggesting a small contribution of these traits for the genetic correlated response of fillet and carcass dress yield.