The Growth Performance of the Hybridization Offspring of Israel Strain Red Tilapia and Other Tilapia Populations in Sea Water

Abstract:

Brood stock was collected from Israel strains red tilapia, GIFT strain of Nile tilapia (Oreo¬chromis niloticus), Blue tilapia (O. aureus), and Nile tilapia (O. niloticus) to form a base population of tilapia with broad genetic variation. Using artificial oriented mating, we obtained 15 full-sib families by inbreeding within the Israel strain red tilapia population and 65 full-sib families from crossing filial generation between Israel strain red tilapia and other tilapia populations. The subjects were tagged when the mean body weight in a family was 58 g. Forty tagged individuals were randomly selected from each family and cultured in sea water with the salinity gradually increased to 28. After 150 days we measured the body length and the body weight of the subjects, and estimated the crossbreeding and genetic parameters of tilapia. Offspring of Israel strains red tilapia and Egyptian strain of Nile tilapia (R×N) showed the highest growth rate. The average body length, the average body weight and the absolute growth rate (AGR) of the first selected generation of R×N were 24.44 cm, 385.23 g and 4.94 g/d respectively. ANOVA analysis showed that there were significant differences (P<0.05) in the body length and the body weight. The multiple comparisons of LSD test in the body length and the body weight indicated that R×N were significantly different (P<0.05) from other three intercross populations (A×R, R×A, and R×J) and the self-reproducing population (RT), except for J×R. Based on the data of 2496 subjects from 80 full-sib groups of tilapia, we estimated the heritability of the body weight. The model was composed of different factors including the average body weight in the tagged family (covariate), tanks and sex effects, etc. The estimated heritability of the body weight was medium (0.46±0.07). Our results suggested that there was a great potential in the genetic improvement of tilapia through the selective breeding. This should provide the theoretical guidance for the mariculture and breeding of salt-tolerant strains of tilapia.