Parâmetros genéticos para características de desempenho e morfométricas em tilápias do Nilo (Oreochromis niloticus)

Abstract

The aim of this study was to estimate the (co) variance and genetic parameters for performance traits (weight and average daily weight gain) for two generations of Nile tilapia (Oreochromis niloticus), GIFT strain belonging to Breeding Program State University of Maringá. We used 3,918 animals, the univariate and bivariate were taken from the animal model using Bayesian inference by the application program MTGSAM (Multiple Trait Gibbs Sampler using in Animal Model). The proposed model includes the effects cages, generation and gender, common hatchery environments (random) and nursery environment (nalev) in addition to additive genetic effects. For analysis, we used the scheme of the long chain of 500,000 cycles, discard sample of 50,000 cycles and sampling intervals of ten cycles. For the purposes of cages, year of birth and sex, it was considered as having flat distribution for the additive genetic and common environment hatchery and nursery, we have assumed the distribution of inverted chi-square for univariate and range reversed to the bivariate analysis. Estimates of heritability coefficient in univariate for weight, weight gain, total length, standard length, height, width and head were 0.15, 0.19, 0.23, 0.19, 0.17, 0 , 15, and 0.17, respectively. The genetic and phenotypic correlations were found in medium to high magnitude ranging from 0.68 to 0.95. The values of Spearman and Pearson correlations for the ratings of the breeding value of morphometric features in the speed of weight gain ranged from 0.58 to 0.98 to 0.63 to 0.99, respectively. The values of genetic gain, the effective population size and inbreeding coefficient for the second generation (G2) were 2.6%, 94 and 0.005, repectively, and the third generation (G3) were 8.1%, 124 and 0.004, repectively.