Submitted to: Aquaculture
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/11/2008
Publication Date: 6/10/2008
Citation: Pierce, L., Palti, Y., Silverstein, J., Barrows, F.T., Hallerman, E.M., Parsons, J.E. 2008. Evaluation of family growth response to fish meal and plant-based diets in rainbow trout (Oncorhynchus mykiss). Aquaculture. 278:37-42. Interpretive Summary: Both environmental and economic concerns have led to the development of fishmeal free diets for salmonids. The ability of rainbow trout to efficiently utilize plant-based diets for growth, and the genetic variation within populations for this trait have not been thoroughly examined. Growth in farmed rainbow trout can depend on heritable traits that dictate how fish respond to particular diets. Farmers need more information on identifying growth traits, enabling them to select fish with desirable growth characteristics. Success in this project will define appropriate selection methods for improving growth in rainbow trout using plant based diets, ascertain the effectiveness of microsatellite DNA marker analysis for pedigree assignment in a commercial aquaculture setting, and establish the groundwork for marker-assisted selection programs for growth on plant-based diets in rainbow trout.
Technical Abstract: Both environmental and economic concerns have led to the development of fishmeal free diets for salmonids. The ability of rainbow trout to efficiently utilize plant-based diets for growth, and the genetic variation within populations for this trait have not been thoroughly examined. In a previous study we used microsatellites to determine the pedigree of the top 1% and bottom 1% of progeny in a commercial growth trial of 20 full-sib families reared in a common environment. Half of the fish from each family was fed a standard fish-meal based diet and the other half was fed a plant-protein (gluten) based diet. The family rankings were similar when either diet was fed, indicating that no genotype x diet interaction was present in that commercial trout strain. In the present study, growth of a pedigreed population from another commercial strain was assessed while feeding both plant-based and traditional fish-meal diets. Also, in this study soybean oil was included in the plant protein meal diet. Families (95 full-sib or 47 half-sib) were reared in a common environment and parentage assignment performed on approximately 1000 fish fed each diet. The fish fed control (fish meal/oil) diet were significantly larger than the fish fed the plant diet. Unlike the previous study, a significant genotype x diet effect was detected which accounted for 5% of the random variation and the genetic correlation for growth on the two diets was 73%. Differences between the two studies may have been caused by the addition of soybean meal and oil to the plant-based diet used and the experimental design that enabled quantitative assessment in the current study. The use of a different strain may have contributed to the difference as well. The genetic variation we identified can be explored to identify and select for genes involved in improved utilization of plant-based diets containing soybean meal and oil.