Abstract
The aquaculture industry is increasingly replacing fishmeal in feeds for carnivorous fish with soybean meal (SBM). This diet change presents a potential for genotype-environment (G × E) interactions. We tested whether current salmonid breeding programmes that evaluate and select within fishmeal diets also improve growth and efficiency on potential future SBM diets. A total of 1680 European whitefish from 70 families were reared with either fishmeal- or SBM-based diets in a split-family design. Individual daily gain (DG), daily feed intake (DFI) and feed efficiency (FE) were recorded. Traits displayed only weak G × E interactions as variances and heritabilities did not differ substantially between the diets, and cross-diet genetic correlations were near unity. In both diets, DFI exhibited moderate heritability and had very high genetic correlation with DG whereas FE had low heritability. Predicted genetic responses demonstrated that selection to increase DG and FE on the fishmeal diet lead to favourable responses on the SBM diet. Selection for FE based on an index including DG and DFI achieved at least double FE gain versus selection on DG alone. Therefore, current breeding programmes are improving the biological ability of salmonids to use novel plant-based diets, and aiding the aquaculture industry to reduce fishmeal use.
Highlights
The use of fishmeal in aquaculture feeds has become a major issue as the global industry continues to grow [10]
Only weak diet G × E interactions were detected for growth, feed intake and feed efficiency in European whitefish
Increased soybean meal (SBM) use in feeds does not compromise the genetic improvements achieved by breeding programmes
Summary
The use of fishmeal in aquaculture feeds has become a major issue as the global industry continues to grow [10]. Breeding programmes exist for all major farmed carnivorous fish species, and have achieved improvements in growth, feed efficiency, disease resistance and product quality traits [12]. Future plant-based diets may impact fish breeding programmes if genotype-environment (G × E) interactions occur. In a worst-case scenario, superior genotypes on a fishmeal diet would be inferior on a plant-based diet This would be shown by a negative genetic correlation between diets [8]. To quantify the impact of G × E interaction on selection response, we predicted genetic changes occurring on both diets in response to alternative strategies of selection for growth or feed efficiency on either fishmeal or soybean meal-based diets
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