Genetic evaluation of Nile tilapia in a five‑year selection

Abstract

The objective of this work was to estimate genetic parameters and breeding values for body weight at harvest and daily weight gain of Nile tilapia (Oreochromis niloticus), evaluated in cages for five years. The data set contained records of 6,650 animals, with predicted breeding values of 8,590 animals in the relationship matrix. The number of animals evaluated was 2,196 (33 families) in 2008; 1,721 (58 families) in 2009; and 2,733 (78 families) in 2010. Single and two‑trait analyses from the data set were performed using Bayesian inference methodology by the computer program MTGSAM. The obtained heritability estimates were of medium magnitude, as follows: 0.273, for daily weight gain; and 0.282, for body weight at harvest. The participation of common environmental effects in the total variation was of 15% for larvae and 5% for nurseries. The genetic and phenotypic correlations were of 95%, indicating a strong association between the traits. Genetic gain was 3.8% per generation, with accumulated 15% over four generations. There were genetic progress and changes caused by the selection of Nile tilapia in the evaluated growing conditions. The selection for weight gain allows of indirect gains associated to weight.