Avaliação genética de peso e rendimento de carcaça de tilápias do Nilo ao longo de cinco gerações de seleção em ambientes sustentáveis

Abstract

Ponds and net cages are the most common farming systems used to raise Nile tilapia. However, problems such as water scarcity, predators and low water quality are recurrent in this type of environment. Water Recirculation System (RAS) and Biofloc Technology (BFT) exist as an option for closed cropping systems little affected by environmental variations, which allow greater control of water quality parameters, biosecurity in addition to causing less environmental impact. Genetic improvement programs in BFT and RAS emerge as a need to adjust to the requirements increasingly incident in the scope of sustainable production. Characteristics related to tilapia weight are the main selection criteria in tilapia breeding programs. Information on genetic parameters for carcass yield is scarce so far. The indirect response is a strategy used to obtain genetic gains in phenotypes that are not selection criteria through existing genetic correlations, heritability and selection intensity. The genetic trend of body weights at standard ages was increasing for all weight traits. For carcass yields, the responses were close to zero. The genetic trend represents accumulated genetic gain over the studied period of 56% for adjusted weight at 56 days of age (P56), 45% for adjusted weight at 168 days in BFT (P168BFT), 16% for adjusted weight at 168 days in RAS (P168RAS), 43% for adjusted weight at 224 days in BFT (P224BFT), 9% for adjusted weight at 224 days in RAS (P224RAS) and null for carcass yield in BFT (RCARBFT) and carcass yield in RAS (RCARRAS). For P56, P168 and P224 the responses indicated that the genetic change is being achieved in the intended direction in BFT and RAS, and that these are sustainable and promising culture options for the weight gain of Nile tilapia cultivated up to 224 days of age.