2007 Annual Report 1a.Objectives (from AD-416) The objective of this research is to determine if a genotype x feed interaction exists among different commercial strains of rainbow trout, and to compare protein retention, fatty acid profiles, and enzyme function in fish fed the plant-based and fish-meal based diets. 1b.Approach (from AD-416) The compositional alteration of fish consuming the plant-based diet compared to the fishmeal control diets will be acessed. In this context the fish will be assayed for fillet yield, muscle protein and lipid content, whole body lipid and muscle fatty acid composition over time. Samples of juveniles (100 g) and market fish (450 g) and broodfish will be assayed for the above parameters with 20 samples per time point on each diet. Trout eggs will be assayed for fatty acid profile to assess alteration due to dietary life history. Determinate enzymes necessary for fatty acid partitioning will be examined. Samples will be obtained and tested from two separate groups consisting of the top and bottom performing families. Liver samples will be kept from fish for the metabolic partitioning and compositional analyses section and fish from families that show extremes in fatty acid partitioning. Initial analyses will consist of microarray analysis of pooled samples from each group (high vs low growth performers and groups with significant fatty acid profiles). Real-time PCR assays will be generated for these genes and their levels will again measured using this more precise method. Initial samples will also be tested for RT-PCR gene expression for specific known regulatory fatty acid oxidation genes such as delta-6 desaturase, SREBP (a sterol regulatory compound), thioesterase, and thiolase as sometimes significant changes in gene expression can exist in genes that are not picked up by microarray analyses. Documents Trust with Trout Lodge. Log 31426. 3.Progress Report This report serves to document research conducted under a trust agreement between ARS and TroutLodge Inc. Additional details of research can be found in the report for the parent project, 5366-21310-003-00D, “Integration of nutritional, genetic and physiological approaches to improve production efficiency of rainbow trout.. Ingredient supplies, market factors, environmental regulation, and consumer preference are resulting in a shift from traditional type diets to diets containing high levels of plant products. TroutLodge is the world largest producer of trout eggs and is concerned that strains of fish selected to grow quickly when fed fish meal diets, may not be the fastest growing strains when fed plant based diets. To answer this question a collaborative study in underway to address the following concerns;. 1)Compare reproductive performance and subsequent fry survival and growth on parents maintained on a plant-based (using plant protein and higher levels of plant-derived lipids) and fishmeal diets.. 2)Examine comparative growth parameters (family means as opposed to tail analysis) for fish from a more typical mating design (increased numbers of families directly from a commercial selection program design).. 3)Test for the presence/absence of genotype x feed interaction in a different commercial strain of rainbow trout, using the improved power of the greater number of full- and half-sib families.. 4)Compare the “common garden” approach to family rearing directly to a traditional commercial approach.. 5)Develop and test a new genotyping system for efficient parentage assignment on a commercial scale.. 6)Compare protein retention, fatty acid profiles, and enzyme function in fish fed the two diets. The study will be terminated in August 2007 and samples be collected and analyzed, with a final report completed in 2008. Communication is through Confernce calls and meetings on a regular basis.