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ARS Home » Pacific West Area » Aberdeen, Idaho » Small Grains and Potato Germplasm Research » Research » Research Project #428348

Research Project: Integrating the Development of New Feed Ingredients and Functionality and Genetic Improvement to Enhance Sustainable Production of Rainbow Trout

Location: Small Grains and Potato Germplasm Research

Project Number: 2050-21310-005-00-D
Project Type: In-House Appropriated

Start Date: Dec 28, 2014
End Date: Dec 27, 2019

Objective:
Six objectives will be used to improve the efficiency of trout production by the development of alternative feeds and fish better able to use those feeds. Some ingredients are developed in-house and we have both laboratory and pilot scale production capabilities. Digestibility of nutrients from specific ingredients has traditionally been conducted with large fish. The effect of strain and size will be determined. A tank system is available to collect feces both by sedimentation and stripping. The effect of strain and size on protein and amino acid retention will be conducted to determine the need for strain or life stage specific diets. Most trout culture use water from one raceway to another up to 5 times. A 36 tank system located on a commercial farm that receives water from 1st, 3rd, or 5th use will be used to determine the effect of water quality as a stressor on specific mineral and fat soluble vitamins in the tissues. A strain of trout selected to utilize plant-based diets is available and the effect of the gut microflora communities will be characterized. Fish oil has been the source of the heart/brain healthy fatty acids, EPA/DHA. This source is limited by supply and cost. Variability among trout in a specific strain for their ability to biosynthesize EPA/DHA has been identified. Trout with this trait will be bred to enhance the nutritional quality of the fillet for the benefit of the consumer. Objective 1: Develop and evaluate new ingredients and ingredient processing methods to increase nutritional and economic value. 1.A: Develop an improved soybean processing method to simultaneously separate protein and oil and remove anti-nutrients. 1.B: Development of alternative methods for the concentration of protein from wheat, barley, and oats. 1.C: Determine the nutritional and economic value of new and modified ingredients. Objective 2: Determine whether stage specific and strain specific diets are needed by evaluating nutrient digestibility at key life stages with different strains of rainbow trout. 2.A: Determination of the effect of fish size and strain on nutrient digestibility. 2.B: Evaluate the effect of fish size and strain on protein and amino acid retention efficiency. Objective 3: Improve performance of rainbow trout in serial-reuse raceway systems by improving water quality, particularly through modifications to feed formulations, and testing of fish strains. 3.A: Performance of rainbow trout in a serial-reuse system is improved by feeding diets formulated to mitigate stress. 3.B: Develop feed formulation strategies that prevent diarrhea in trout to facilitate waste management. Objective 4: Determine the genetic, physiological, and gut microflora components for improved utilization of plant-based feeds by rainbow trout. 4.A: Isolation and identification of trout microbiota and evaluation of its role in enhanced tolerance to utilization of plant-based feeds. 4.B: Determine the effect of transplantation of microbiota from selected fish. Objective 5: Develop lines of rainbow trout with enhanced abilities to biosynthesize EPA and DHA from plant oils and deposit these nutrients in muscle tissue.

Approach:
Objective 1: 1.A: An improved aqueous processing method that results in high oil and protein recovery and removal of anti-nutrients will reduce the diarrheic effect of soybeans for trout. Experiments to optimize pretreatment and extraction conditions will be conducted. 1.B: Improved processing methods will increase the nutritional and economic value of protein concentrates from wheat, barley and oats. Trials will be conducted with wheat to optimize starting material and processing conditions to concentrate to 70% protein, and remove the binding effect. This effect of wheat gluten limits inclusion level in extruded feeds. Protein concentrates of barley and oats will be produced using another aqueous fractionation method that features alkaline extraction, centrifugation, and acid precipitation of supernatant. 1.C: A seven phase program will evaluate the nutritional value of alternative ingredients. Complete nutrient and anti-nutrient analysis, fry screening trials, effect on feed intake and extrusion, nutrient digestibility, growth trials, and effect on fecal size will be conducted. Objective 2: 2.A: Nutrient digestibility is affected by either fish size or strain or both. The ADC’s for major nutrients and amino acids will be determined with four unique strains of trout at three sizes (15, 500, 1500 g, 12 trials). 2.B: Nutrient retention efficiency is affected by fish size or strain or both. The same strains and fish size will be used as in 2.A in 12 week growth studies to evaluate protein and amino acid retention. Four diets varying in protein (40/45%) and lipid (20/25%) will be fed. Objective 3: 3.A: Improved diets containing elevated levels of stress-affected minerals and fat soluble vitamins will improve performance of rainbow trout raised in serial-reuse water. The effect of water source (1st, 3rd, & 5th use) as a stressor in three strains of rainbow trout on tissue concentrations of fat soluble vitamins and minerals will be determined. 3.B: Specific combinations of ingredients and prebiotics affect intestinal inflammation and the consistency of rainbow trout feces. To improve waste management dietary factors that affect fecal particle size will be determined. Objective 4: 4.A: Intestinal microflora community structure in rainbow trout is affected by diet and host genotype. Microbial communities will be identified in two strains of trout, one susceptible to soy enteritis and the other resistant. 4.B: Transplantation of microbiota from selected trout fed plant-based feed into non-selected trout will reduce intestinal enteritis when fed plant-based feeds. A cross-over experimental design will be used to determine if different microbial communities can protect a trout from soy induced intestinal enteritis. Objective 5: The ability to biosynthesize EPA and DHA in muscle tissue of rainbow trout fed diets containing plant oils can be selectively enhanced. To evaluate the potential to increase the ability of trout to biosynthesize EPA and DHA in their muscle, variation among individuals and families of rainbow trout will be determined. Individuals with known performance values for this trait will then be selectively bred.