A switch from fish- to plant-protein based feeds will not harm the current breeding program for European whitefish: Evidence from genetic analysis of feed utilisation traits
Authors: Quinton Cheryl D. , Kause Antti , Koskela Juha 
Published: April 2019

A selective breeding program is currently under development that aims to enhance farmed European whitefish (Coregonus lavaretus L.), in order to increase aquafood supply chain productivity and consumer satisfaction in Finland. Critical steps in developing a breeding program are determining the amount of genetic variation in the population, and predicting how selection to change one trait may impact other traits. Diets for carnivorous fish currently contain protein mostly derived from wild fish sources. In order to reduce feed costs and environmental impact, alternative plant proteins have been researched for aquaculture diets. An issue of concern to the whitefish breeding program is the possibility of genotype by environment interaction (GxE), specifically that fish produced by the breeding program with the current diets may not perform well when they are reared with future plant-protein based diets. The aims of this study were (i) to assess whether sufficient genetic variation exists to improve growth, feed intake and feed efficiency on both types of diets through selection, and (ii) to predict whether selection on a fish meal (FM) based diet will lead to favourable correlated changes on a potential future soybean meal (SBM) based diet. Seventy families were created from a series of factorial matings. Twenty-four individuals from each family were tagged and allocated to one of two diet treatments: a FM protein diet or a SBM protein diet. Individual weights were recorded at the beginning and end of the 3-month growth trial. During the trial, daily feed intake was measured 5 times per individual with X-radiography. Genetic parameters of final body weight, daily gain, daily feed intake, and feed efficiency were estimated with multiple-trait animal models. Fish on the FM diet had faster growth, higher final weight, lower feed intake, and accordingly higher feed efficiency than those on the SBM diet. For both diets, daily gain showed the highest heritability (h2=0,20-0,40), feed intake had lower h2 (0,17-0,23), and feed efficiency and body weight had the lowest h2 (0,05-0,07). Each trait appeared to show sufficient genetic variation for selective improvement for both diets. Daily gain and feed intake had high positive correlations (rP and rA>0,86) within both diets. Heritabilities were similar on both diets, and genetic correlations between the same traits recorded in each diet were very high (rA>0,92). This indicates that little GxE exists for these traits, and selection to improve growth and feed utilization on the FM diet will have correlated improvement for the SBM diet. In conclusion, the results of this study are favourable, and indicate that present selection to improve growth, feed intake, and feed efficiency within a FM-based diet will also improve the population for these traits within a SBM-based diet. Therefore, the improved population is likely to continue performing well as aquaculture diets move toward increased SBM protein contents.