Evaluation of genetic parameters for feed efficiency traits and growth traits in turbot (Scophthalmus maximus)

Turbot is a crucial species in seawater aquaculture, with feed costs constituting the highest proportion of breeding expenses. Developing a new turbot variety with high feed efficiency can effectively reduce breeding costs and promote industrial development. To facilitate breeding efforts, it is essential to first evaluate the genetic parameters of feed efficiency traits, including feed conversion efficiency (FCE) and residual feed intake (RFI). This experiment involved 2160 juvenile turbot from 72 full-sib families, using a specially designed cage culture system to measure individual FCE and growth traits and conduct genetic parameter evaluation. The phenotypic value of the FCE trait ranged from 0.060 to 1.566, with differences between families ranging from 0.732 to 1.345. The heritability estimates for body weight and body length were 0.38 and 0.52, respectively. Notably, the heritabilities for FCE and RFI were estimated to be 0.61 and 0.43, demonstrating substantial potential for genetic improvement. The genetic correlation between FCE and body weight varied significantly across developmental stages: it was moderate at the initial stage (rg = 0.54) but increased to a highly positive level at the final harvest stage (rg = 0.79). This indicates that indirect selection for FCE via body weight is highly effective. Furthermore, genotypic RFI exhibited complete genetic independence (rg = 0.00) from body weight. This demonstrates that RFI is not influenced by body weight, making it a superior and independent selection index to breed feed-efficient turbot. The findings of this study provide a necessary genetic foundation for developing new turbot varieties with superior feed conversion efficiency.