Estimating genetic parameters with molecular relatedness and pedigree reconstruction for growth traits in early mixed breeding of juvenile turbot

An introduced turbot population was used to establish families and to estimate genetic parameters of the offspring. However, there is a lack of pedigree information, and common environmental effects can be introduced when each full-sib family is raised in a single tank. Therefore, in the genetic evaluation, SSRs (simple sequence repeats) were used to reconstruct the pedigree and to calculate molecular relatedness between individuals, and the early mixed-family culture model was used to remove the impact of the common environmental effects. After 100 d of early mixed culture, twenty SSRs were used to cluster 20 families and to calculate paired molecular relationships (n=880). Additive genetic matrices were constructed using molecular relatedness (MR) and pedigree reconstruction (PR) and were then applied to the same animal model to estimate genetic parameters. Based on PR, the heritabilities for body weight and body length were 0.214±0.124 and 0.117±0.141, and based on MR they were 0.101±0.031 and 0.102±0.034, respectively. Cross validation showed that the accuracies of the estimated breeding values based on MR (body weight and body length of 0.717±0.045 and 0.629±0.141, respectively) were higher than those of PR (body weight and body length of 0.692±0.052 and 0.615±0.060, respectively). The MR method ensure availability of all genotyped selection candidates, thereby improving the accuracy of the breeding value estimation.