Evaluation of family growth response to fishmeal and gluten-based diets in rainbow trout (Oncorhynchus mykiss) Yniv Palti a, ⁎ , Jeffrey T. Silverstein a , Heather Wieman b , John G. Phillips c , Frederic T. Barrows d , James E. Parsons e a National Center for Cool and Cold Water Aquaculture, ARS-USDA, 11861 Leetown Rd., Kearneysville, WV 25430, USA b Department of Pharmacology and Cancer Biology, Duke University Medical Center, Box 3813, Durham, NC 27710, USA c NAA-ARS-USDA, 600 E. Mermaid Ln., Wyndmoor, PA 19038, USA d USDA-ARS, Hagerman Fish Culture Experiment Station, 3059-F National Fish Hatchery Road, Hagerman, ID 83332, USA e Troutlodge, Inc., 12000 McCutcheon Rd., Sumner, WA 98390, USA Received 8 March 2005; received in revised form 23 November 2005; accepted 25 November 2005 Abstract 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 (P b 0.001). 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. Keywords: Oncorhynchus mykiss; Selection; Plant diets; Breeding; Microsatellites; Parentage determination; Triploidy 1. Introduction The aquaculture industry has received a large amount of criticism in recent years regarding the volumes of fishmeal and fish oils used in the manufac- ture of feeds, particularly for salmonid diets. Increasing concerns over potential negative environmental impacts, from both an effluent water quality standpoint Aquaculture 255 (2006) 548 – 556 www.elsevier.com/locate/aqua-online ⁎ Corresponding author. National Center for Cool and Cold Water Aquaculture, ARS-USDA, 11861 Leetown Rd., Kearneysville, WV 25430, USA. Tel.: +1 304 724 8340x2134; fax: +1 304 725 0351. E-mail address: ypalti@ncccwa.ars.usda.gov (Y. Palti). 0044-8486/$ - see front matter. Published by Elsevier B.V. doi:10.1016/j.aquaculture.2005.11.029