Evaluation of family growth response to fishmeal and gluten-based diets in rainbow trout (Oncorhynchus mykiss)

A study was conducted to evaluate genotype×feed interactions in a commercial strain of rainbow trout (Oncorhynchus mykiss). Microsatellite DNA markers were used to determine the pedigree of the top 1% and bottom 1% of progeny in a large scale commercial growth trial of 24,000 rainbow trout from 20 full-sib families (20 dams×10 sires in a nested mating design). The progeny were pooled at eyed stage and divided into 2 groups. Half of the fish from each family were fed a standard fishmeal-based diet and the other half was fed a plant protein (gluten)-based diet to determine the relative family rankings in each diet. The primary protein sources in the plant protein-based diet were corn gluten and wheat gluten meals. Krill was supplemented to this feed for the early life stages (starter, #1, #2, #3 crumbles), but was eliminated in the larger pellet sizes. Large genetic variation for growth was identified for both diets and the sire effect was found to be highly significant (Pb0.001). The family rankings were similar for both diets, which suggest that the fish that grow faster on fishmeal diet are likely to grow faster on plant protein-based diets, and therefore current commercial strains that exhibit superior growth should retain their improved performance if raised on gluten-based diets. Multiplexing microsatellite markers would further improve the efficiency of parentage assignment protocols in large-scale rainbow trout selection programs. Published by Elsevier B.V.