Genetic parameter estimates for reproductive traits and egg composition in Pacific white shrimp Penaeus (Litopenaeus) vannamei

Abstract

We estimated the heritabilities and genetic correlations for reproductive traits and egg composition in female shrimp, Penaeus (Litopenaeus) vannamei. The traits under analysis were days to first spawn after ablation (DTFS), egg diameter (ED) and number (EN), and egg triacylglycerides (TG), vitellin (VIT), total protein (PROT) and total lipids (LIP) for first spawned eggs. Estimates were based on 1–11 females from 30 full-sib families produced in 2000 and derived from the so-called ‘Melagos’ line in Mexico. Heritabilities were estimated using REML procedures from data on females that spawned at least once (56%). For ED, EN, and VIT, TG, PROT, and LIP in eggs, a square root transformation was done to normalize the data. Data was analysed using two models, one did not include any other trait as covariate, and the other included other trait as covariate. For DTFS the total number of spawns/female was used as covariate. For VIT, TG, PROT, and LIP in eggs the covariate used was egg number in that spawn. For egg number and egg diameter the other variable was reciprocally used as covariate. Heritabilities estimated without covariates were 0.41 for DTFS, 0.09 for EN, 0 for ED, 0.28 for VIT, 0.20 for TG, 0.13 for PROT, and 0 for LIP. Heritabilities for all traits but lipids increased when the covariates were introduced in the estimation of variance components; 0.54 for DTFS, 0.17 for EN, 0.07 for ED, 0.47 for VIT, and 0.35 for TG, 0.18 for PROT, and 0 for LIP. Despite large standard errors caused by small effective sample size, the estimates of the heritabilities indicate that these traits can be subjected to selection to improve reproductive output from females.