Aquaculture

Improving commercial body weight in turbot using records from fish measured under production conditions

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Abstract

In aquaculture selective breeding programs, growth is typically the main breeding objective, and selection decisions are often based on weight recorded in selection candidates reared in the nucleus under controlled conditions. However, selection based solely on nucleus performance may be inefficient for improving commercial body weight due to differences in husbandry conditions and the existence of genotype-by-environment interactions. In this study, we treat genotype-by-environment interaction by modelling performance in the two different environments (nucleus and commercial) as two genetically correlated traits. To effectively improve commercial weight, genetic evaluations should incorporate phenotypic records of sibs of nucleus candidates reared under commercial conditions. However, the optimal number of sibs remains unknown. This simulation study modelled a turbot selective breeding program to evaluate how many sibs should be sampled under commercial conditions to achieve accurate breeding value estimation for commercial body weight and a large selection response for this trait. Heritabilities for both nucleus and commercial weights were set at 0.30, and three genetic correlations between the traits (0.2, 0.5 and 0.8) were considered. BLUP and genomic BLUP (GBLUP) evaluation methods were assessed over five generations. Each generation, the 100 males and 100 females with the highest estimated breeding values for commercial weight were selected from a pool of 2,000 candidates. These selected males and females were randomly paired, creating 100 full-sib families per generation. Each mating produced 20 offspring to be reared as selection candidates in the nucleus and a varying number of offspring (0-60 per family) to be reared under commercial conditions. Incorporating information from sibs reared under commercial conditions markedly increased the accuracy of breeding value estimation and, consequently, the genetic gain for commercial weight, particularly when the genetic correlation between this trait and nucleus weight was low. Under the lowest genetic correlation (0.2), after five generations of selection, using data from only 10 commercial sibs resulted in a 310% and 347% increase in genetic gain for BLUP and GBLUP, respectively. In contrast, under the highest genetic correlation (0.8), the corresponding improvements declined to 17% for BLUP and 20% for GBLUP. Regardless of the genetic correlations, both accuracy and genetic gain continued to rise as more sibs were included, although the marginal benefits diminished at higher numbers. In terms of inbreeding, incorporating data from commercial sibs led to higher inbreeding coefficients in BLUP scenarios, but this increase was smaller as the number of sibs grew. In contrast, in GBLUP scenarios, inbreeding coefficients remained similar to those observed when no sibs were included. Overall, our results indicate that increasing the number of sibs beyond 50 per family in both BLUP and GBLUP provides only minimal improvements in accuracy, genetic progress and inbreeding, which may not justify the additional cost and effort.

Keywords: 2026

How to Cite:

Morales-González, E., García-Ballesteros, S., Villanueva, B. & Fernández, J., (2026) “Improving commercial body weight in turbot using records from fish measured under production conditions”, World Congress on Genetics Applied to Livestock Production Digital Archive 2026(1): 2285429. doi: https://doi.org/10.31274/wcgalp.23701

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