GENETIC PARAMETERS FOR PERFORMANCE TRAITS IN A BASIC POPULATION OF TILAPS Oreochromis sp.

Heritabilities and genetic correlations are key parameters for defining the objectives and selection methods used in breeding programs .  Although some tilapia breeding programs have already been consolidated in Brazil, a large part of the farmed animals comes still from unimproved populations. Thus, initiatives to establish breeding programs in different regions of the country can make production more efficient.  We estimate genetic parameters of productive traits for a tilapia base population evaluated in the recirculation system.

A base population (G0) with 413 individuals from 24 tilapia families was established at the Center for Research and Diffusion of Technology in Aquaculture at the Federal University of Lavras - Brazil (UFLA).  The families remained isolated each other until reaching about 10 grams to be identified with microchip, generating a common fry environment effect.  After identification the animals were reared for 150 days in 500 L tanks of a closed recirculation system with temperature an oxygen controlled.  The weight and measures of standard  and head  length, body height and width were collected and evaluated according to a bicaracter animal model that considered the fixed effects of tank and sex, and the additive genetic and fry random effects.  Bayesian procedures implemented in the MTGSAM software were used for estimates of the (co)variance components and genetic parameters.

Estimates of the rooting effect were quite high, demonstrating the importance of including this effect in the genetic prediction models.  The estimated heritabilities are moderate to high, demonstrating a good genetic gain potential by selection for this population. The standard length was the variable most correlated with the weight and could be used as an indirect selection criterion. However, the credibility intervals were very broad for all parameters, which makes the estimates unreliable (Table 1).  In general, the results show a good potential to establish a breeding program from this base population, however, an evaluation with more individuals and a greater number of families should be performed before beginning the selection process.

Financial support: FAPESP (2018/10908-3)