Uniformity of body weight is a trait of great economic importance in the production of white shrimp (Litopenaeus vannamei). A necessary condition to improve this trait through selective breeding is the existence of genetic variability for the environmental variance of body weight. Although several studies have reported such variability in other aquaculture species, to our knowledge, no estimates are available for shrimp. Our aim in this study was to estimate the genetic variance for weight uniformity in a farmed population of shrimp to determine the potential of including this trait in the selection program. We also estimated the genetic correlation of weight uniformity between two environments (selection nucleus and commercial population). The database contained phenotypic records for body weight on 51,346 individuals from the selection nucleus and 38,297 individuals from the commercial population. A double hierarchical generalized linear model was used to analyse weight uniformity in the two environments. Fixed effects included sex and year for the nucleus data and sex and year-pond combination for the commercial data. Environmental and additive genetic effects were included as random effects. The estimated genetic variance for weight uniformity was greater than 0 (0.06 ± 0.01) in both the nucleus and commercial populations and the genetic coefficient of variation for the residual variance was 0.25 ± 0.01. The genetic correlation between weight and weight uniformity was close to zero in both environments. The estimate of the genetic correlation of weight uniformity between the two environments (selection nucleus and commercial population) was 0.64 ± 0.06. The existence of genetic variance for weight uniformity suggests that genetic improvement of this trait is possible. Selection for weight uniformity should not decrease weight, given the near zero genetic correlation between these two traits. The strong genetic correlation of weight uniformity between the two environments indicates that response to selection for uniformity in the nucleus will be at least partially transmitted to the commercial population if this trait is included in the breeding goal.

中文翻译：

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太平洋白对虾（Litopenaeus vannamei）收获重量均匀性的遗传参数。

体重的均匀性是白虾生产中重要的经济特征。通过选择性育种改善该性状的必要条件是存在体重环境变异的遗传变异性。尽管有数项研究报告了其他水产养殖物种的这种变异性，但据我们所知，尚无虾的估计数。我们在这项研究中的目的是估计养殖对虾种群体重均匀性的遗传方差，以确定将该特性纳入选择程序的可能性。我们还估计了两种环境（选择核和商业人群）之间体重均匀性的遗传相关性。该数据库包含51个体重的表型记录，选择核中有346个人，商业人群中有38,297个人。使用双层广义线性模型来分析两种环境下的重量均匀性。固定效应包括核数据的性别和年份，商业数据包括性别和年份的组合。环境和累加遗传效应作为随机效应包括在内。在核种群和商业种群中，体重均一性的估计遗传方差均大于0（0.06±0.01），而剩余方差的遗传变异系数为0.25±0.01。在两种环境下，体重和体重均匀度之间的遗传相关性接近于零。两种环境（选择核和商业人群）之间体重均匀性的遗传相关性估计为0。64±0.06。体重均一性遗传变异的存在表明该性状的遗传改良是可能的。鉴于这两个性状之间的遗传相关性几乎为零，因此选择体重均匀性不应降低体重。两种环境之间体重均匀性的强遗传相关性表明，如果将这种性状纳入育种目标，则对细胞核中均匀性选择的反应将至少部分传递给商业人群。