Evaluation of growth performance in Litopenaeus vannamei population introduced from other nations

In 2011，seven batches of Litopenaeus vannamei, introduced from American and Singapore were collected to evaluate the growth performance.. The nest design was adopted and 130 full-sib families (17 hybridized combinations and 7 inbreed combinations) were obtained by artificial insemination. Offspring of the 130 families were cultured separately through the larval and juvenile stages, and were fluorescence-tagged when they reached a body length of 3 cm. The shrimps were tagged with a unique family code by injecting different colours of “Visible Implant Fluorescent Elastomers” (VIE) before being stocked in one grow-out pond. All families were randomly divided into two groups and then cultured in both Huanghua, Hebei and Aoshan, Qingdao, simultaneously. Body weight (g) of these shrimps was measured after 153 d. growth performance of every population and combination was evaluated by analyzing the least squares means (LSM) and heterosis for body weight in Litopenaeus vannamei. The results showed that, at 153 d, the variation coefficient of body weight of the Litopenaeus vannamei stocks was 13%~26%. The LSM for body weight of the UA5 batch, UA4 batch and SIN batch were higher than average by 5.34%, 2.51% and 1.67%, respectively. So these 3 batches could be used as parents for high quality watermelon cultivars. A growth performance analysis showed the average LSM of hybridized combination (18.14 g) was higher than the average LSM of inbreed combinations (17.17 g). The highest LSM occurred in the cross between the UA4 batch and the UA5 batch, with 7.61 percent higher than average. Heterosis analysis showed, they ranged from a low of -1.77% to a high of 11.72%, with a mean of 5.45%, positive heterotic vigor was detected in most hybridized combination. The highest heterosis occurred in the cross between the UA1 batch and the UA2 batch. Our study provides insight into methods for improving the accuracy of genetic selection for growth traits in Litopenaeus vannamei，and for genetics and breeding research into quantitative traits in other aquatic animals.