Genetic relationships of body composition and feed utilization traits in European whitefish (Coregonus lavaretus L.) and implications for selective breeding in fishmeal- and soybean meal-based diet environments

¹ MTT Agrifood Research Finland, Biotechnology and Food Research, Biometrical Genetics, FI-31600 Jokioinen, Finland
² Finnish Game and Fisheries Research Institute, Turku Game and Fisheries Research, FI-20520, Finland
³ Finnish Game and Fisheries Research Institute Jyväskylä, Survontie 9, FI-40500 Jyväskylä, Finland

^* To whom correspondence should be addressed. E-mail: cheryl.quinton{at}mtt.fi.

	Abstract

Body composition traits have potential use in fish breeding programs as indicator traits for selective improvement of feed efficiency (FE). Moreover, feed companies are increasingly replacing traditional fishmeal (FM) based ingredients in feeds for carnivorous farmed fish with plant protein ingredients. Therefore, genetic relationships of composition and feed utilization traits need to be quantified for both current FM-based and future plant-based aquaculture feeds. Individual whole-body lipid% and protein%, daily gain (DG), average daily feed intake (ADFI), and FE (daily gain / daily feed intake) were measured on 1,505 European whitefish (Coregonus lavaretus) from 70 half/full-sib families reared in a split-family design with either a typical FM or a novel soybean meal (SBM) based diet. Diet-specific genetic parameters were estimated with multiple-trait animal models. Lipid% was significantly greater in the FM diet group than in the SBM group, even independent of final body weight or total feed intake. In both diets, lipid% showed moderate heritability (0.12 to 0.22), and had positive phenotypic and genetic correlations with DG (0.37 to 0.82) and ADFI (0.36 to 0.88). Therefore, selection against lipid% can be used to indirectly select for lower feed intake. Protein% showed low heritability (0.05 to 0.07), and generally very weak or zero correlations with DG and ADFI. In contrast to many previous studies on terrestrial livestock, lipid% showed zero or very weak phenotypic and genetic correlations with FE. However, selection index calculations demonstrated that simultaneous selection for high DG and reduced lipid% could be used to indirectly increase FE; this strategy increased absolute genetic response in FE by a factor of 1.5 to 1.6 compared to selection on DG alone. Lipid% and protein% were not greatly affected by genotype-diet environment interactions, and, therefore, selection strategies for improving body composition within current FM diets should also improve populations for future SBM diets.

Key Words: feed efficiency, genetic selection, genotype-environment interaction, lipid, protein