Abstract:Genetic parameters of breeding object traits are important to design breeding scheme and evaluate selection response before performing a selective breeding program. In this study, a total of 15000 individuals from 100 families of Litopenaeus vannamei at the juvenile stage were desalinated and reared at a low salinity of 5 to explore the survival rate and the heritability. The results showed that the range of the survival rate at the desalination stage and culture stage were 19.33%–100.00% and 11.9%–99.2%, and the average survival rate were 66.7% and 67.5%, respectively. The range of the overall survival rate at the juvenile stage was 6.67%–90.67% with the average survival rate 46.91%. There were significant differences on the survival rate between families at two stages (P<0.01). There was significant and moderate positive correlation on the survival rate of families between two stages (r=0.61, P<0.01). The heritabilities of survival for two stages were estimated by the model of the additive genetic effect (A) and the model combining A and the common environmental effect (C). Based on the A model, the heritability of survival for the desalination stage, culture stage and combination of two stages were 0.09, 0.10 and 0.14, respectively, which were significantly different from zero (z﹥2.58). Based on the A+C model, heritability of survival were 0.06, 0.05 and 0.07, respectively, which were not significantly different from zero (z<1.96). The genetic correlation on the survival rate of families between two stages for the A and A+C models were 0.41±0.09 and 0.48±0.09, respectively. The additive genetic effect was partially confounded with the common environmental effect because the proportion of half-sib families to full-sib families was only 47% when each family were cultured in a separate cage. Therefore, the heritability estimates based on the A model were overestimated, and the heritability estimates based on the A+C model was underestimated. The results implied that the adaptability of low salinity for Pacific white shrimp can be improved through a selective breeding program.
