1a. Objectives (from AD-416)
The objective of this research is to improve the competitiveness of rainbow trout production by reducing feed costs through the development of improved ingredients, feeds, and strains of rainbow trout.
1b. Approach (from AD-416)
Ingredients will be selected based upon nutrient and anti-nutrient profiles, and cost on a protein unit basis. Special emphasis will be placed upon barley and oat cultivars, but any ingredient that has favorable profiles will be considered. Some marine oils and proteins maybe evaluated at low inclusion levels to enhance feed palatability and the final product fatty acid profile. Practical feed formulations, will be produced using cooking extrusion (commercial conditions) for rapidly growing juvenile fish. Traditional evaluation procedures, including growth performance and nutrient retention, and cost per unit gain, will be used to evaluate the improved diet formulations. Additional evaluation procedures will be developed and applied to fish feeding trials as follows: (1) clinical assays of blood plasma for electrolyte levels, cholesterol, triglycerides, ASAT, ALAT, and routine plasma parameters; (2) whole blood analysis for hematocrit percentages; (3) gene expression activities for genes associated with protein synthesis and degredation, fatty acid elongation and desaturation, bone and/or cartilage metabolism and energy metabolism plus cellular redox status. Reproductive performance of rainbow trout fed diets containing plant-derived ingredients in place of fishmeal and fish oil (partial replacement or total replacement for selected growth periods) will be assessed by measuring fecundity, egg fertility, and egg hatchability, plus chemical analysis of eggs to determine effects of diet on nutritional content. Bone density and imaging may be explored for fish fed diets lacking fishmeal to determine if replacement mineral supplements in plant-based feeds support normal bone development and absence of skeletal deformities.
3. Progress Report
This research specifically address objectives Objective 3, "Determine nutritional value of alternative ingredients (protein, lipid, energy) and develop practical feed formulations for improved strains of fish", Objective 4, "Determine optimal nutrient supplementation levels for specific life stages of improved strains of trout", Objective 5, "Use gene expression analyses to advance the understanding of gene targets for improving nutrition, growth, and development processes under production conditions", and Objective 6, "Identify phenotypic differences in rainbow trout for growth and utilization of plant-based sustainable diets and determine the genetic variation for the identified traits", of the parent project. A variety of collaborative feeding studies were conducted investigating both improved protein and lipid sources. These replacements for fish meal and fish oil were evaluated as well as the effect of feeding these ingredients on select families of trout. These families have been selected over multiple generations for ability to utilize plant-based feeds. Samples were taken for gene expression analysis. Results thus far have significantly assisted in reaching the Project Plan objectives. Communication and coordination was achieved through frequent emails and phone conversations and frequent site visits. Two of our Scientists are co-located with the University of Idaho, Aquaculture Research Institute in Hagerman Idaho.