Estimation of genetic parameters for body weight in a multistage within-family selection process in Pacific white shrimp (Litopenaeus vannamei)

Abstract

The objective of this study was to estimate the genetic parameters of a Pacific white shrimp population (Litopenaeus vannamei), which used within-family selection (WFS) at different stages in commercial production. The characteristics analyzed were body weight at 12 (W12), 14 (W14), and 21 (W21) weeks in family cages within tanks in a genetic nucleus and weight at harvest at 19 weeks. The WFS was carried out employing a size grading machine. Three linear mixed multivariate models were used for data analysis. The base model (Model I) considered as fixed effects for W12, W14, and W21 the tank and the population density inside the cage; and for the weight at harvest the tank and the sex, and the age covariate, as random effects, the additive and common genetic effects of siblings in all the models were considered. To correct for the effects of WFS, Model II included the initial weight at W14 and W21, while Model III included the selection intensity, respectively. The variance components estimated with Models I and III are essentially the same, while with Model II, there is a decrease in the additive variances for weight at 14 and 21 weeks. The heritabilities are between 0.22 and 0.61, while the significant genetic correlations range from 0.44 to 0.51. On the one hand, the results indicate that the multistage within-family selection processes for body weight can interfere in the estimation of the components of (co) variance. Moreover, on the other hand, the (co)variance components estimated for all weights evaluated in this study allow considering selection responses correlated to harvest weight with different degrees of efficiency; however, it is necessary to carry out studies that value responses from a cost-benefit approach in selection programs of this type in Litopenaeus vannamei.