Avaliação de desempenho e divergência de grupos genéticos de tilápia do nilo Oreochromis niloticus

Abstract

The aim of the present study was to compare the growth performance networking of tilapia strains and crossbreds of Oreochromis niloticus. The work was carried out at the Brazilian industry Fish Ltda. Itupeva - SP. Five different genetic groups were evaluated: Chitralada 7/8 (3/4 Chirtralada x Chitralada); Chitralada 5/8 (3/4 Chitralada x 1/2 Chitralada); Tricross (1/2 Chitralada x GIFT); Red-Stirling and Chitralada. Fish sampling was done to acquire the following morphometric variables: standard length (SL), head length (HL), body height (BH), body width (BW), Ellipticity (EL) and reason BW / HL. The following production parameters for each genetic group were estimated: daily weight gain (DWG), weight gain (WG), final body weight (FW), final biomass (FB) and Survival (SB). Applied to analysis of variance (ANOVA) and the Scott Knott test at 5% probability. In addition, data were submitted to multivariate analysis and cluster analysis by UPGMA method, adopting the Mahalanobis distance. There were significant differences (P <0.05) for the biometric variables and performance between genetic groups in each gender class. The genotypes Chitralada 5/8, 7/8 and Tricross, for both sexes showed the best values of DWG, WG and FW to the culture envireoment. The most dissimilar genotypes were 7/8 and Red-Striling, being isolated groups in all used methods. The Tocher method clustered the five genotypes into two groups, the first one comprised genotypes 7/8, 5/8, Tricross and Chitralada and the second one Red-Stirling. The SL and BH variables presented the highest contribution amounts relative to the phenotypic differences of the analyzed genotypes.