Genetic parameters and morphometric characteristics of two generations from the GIFT strain of the Nile Tilapia Parâmetros genéticos e características morfométricas de duas gerações de Tilápia do Nilo linhagem GIFT

The objective of this work was to estimate the (co)variance and the genetic parameters for weight and average daily gain from two national generations of the GIFT strain of the Nile tilapia (Oreochromis niloticus). We evaluated 3918 fish from two generations of the breeding program from the Universidade Estadual de Maringa, Northwestern Parana. Univariate and bivariate analysis were carried out using Bayesian inference. The estimates of heritability using one-trait models for weight was 0.15, average daily gain was 0.19, fish length was 0.23, fish width was 0.19, standard length was 0.17, fish height was 0.15, and the head length was 0.17. The genetic and phenotypic correlations were above 0.68 and 0.95, respectively. The values of Spearman and Pearson correlations for breeding values of the morphometric traits in relation to average daily gain ranged from 0.58 to 0.98 and from 0.63 to 0.99, respectively. In the second generation (G2), the genetic gain was 2.6%, the effective size of the population was 94, and the inbreeding coefficient was 0.005. In the next generation (G3), these values were 8.1%, 124 and 0.004, respectively. The genetic gains over the generations gradually increased from one generation to another, indicating that the criterion, average daily gain, chosen for feature selection was efficient.