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United States Department of Agriculture

Agricultural Research Service

Research Project: Improving Sustainability of Rainbow Trout Production by Integrated Development of Improved Grains, Feeds, and Trout

Location: Small Grains and Potato Germplasm Research

2011 Annual Report


1a. Objectives (from AD-416)
The objective of this research is to improve the sustainability and production efficiency of rainbow trout by developing innovative feeds that reduce dependence on marine fishery resources. Objective 1: Identify and develop grain lines with desirable traits for either direct or indirect use in aquafeeds. Objective 2: Develop mechanical, chemical and biological methods to improve the nutritional and anti-nutritional profile of grains, by-products and other alternative ingredients. 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. 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.


1b. Approach (from AD-416)
A multidisciplinary approach will be used combining expertise in the fields of plant genetics, grain processing, fish nutrition and physiology, and fish genetics. Grain lines will be identified that have traits desirable for fish feeds. Phenotypic differences in trout for their ability to utilize plant-based feeds will also be identified. Grains will be further modified through physical, biological or chemical methods to improve their nutritional profile for trout. Feeds will be formulated using alternative ingredients to fish meal and to meet the nutritional requirements for improved strains of trout This project will benefit; fish farmers through improved feeds and environmental compliance through reduced nutrient release, identified traits and markers to aid stock improvement efforts, feed manufacturers with alternate ingredients, reduced costs, price stability, and improved diet formulations, and grain farmers with new markets and products, and the consumer with a safe, sustainable, nutritious food supply and cleaner environment.


3. Progress Report
Progress was made on all 6 objectives, all of which fall under National Program 106, in Component 1, Understanding, Improving, and Effectively Using Animal Genetic and Genomic Resources, Component 2, Enhancing Animal Performance, Well-being, and Efficiency in Diverse Production Systems, or Component 3, Defining Nutrient Requirements and Nutrient Composition of Feedstuffs and Expanding Alternative Ingredients. Under objective 1B, Develop and Implement Genetic Improvement Programs, we made significant progress in identifying families of trout that demonstrate improved growth and feed efficiency when fed plant-based feeds, compared to unselected trout fed the same diets. This research was conducted both in-house and at a commercial 3rd party site. Progress has also been made under Objective 2A, Improve Growth, Nutrient Utilization, and Well-being to understand the role of feed composition and genetics in protein and energy retention. Interactions of trout family by diet composition on nutrient retention have been investigated and the selected fish have improved protein retention, but not energy retention, compared to the unselected strains. Under objective 3A, Determine Nutrient Requirements, studies have been completed to determine the optimal supplementation level of copper, magenesium and zinc to plant-based or fish meal based diets. Progress was made in several areas under Objective 3b, Evaluate the Nutritional Value of Alternative Sources of Protein and Lipid. Several studies have been conducted examining the processing characteristics and nutritional value of improved lines of soybeans, and 3 forms of corn protein concentrate. A method was also developed to produce a feed grade soy protein concentrate. Significant progress has been made at increasing production to a pilot scale. To assist in supplying affordable grain based products for aquafeeds, two high beta-glucan varieties of barley were developed. Beta-glucan is beneficial for trout under stressful conditions and is also need in the human nutracuetical industry. Distiller dried grains with solubles (DDGS) is a co-product of industrial ethanol production from corn and other cereal grains. Methods have been developed to improve the nutritional value of DDGS for aquafeeds. Laboratory results have been transferred to industry by conducting “on-farm” trials with commercial trout producers evaluating alternative protein ingredients. Significant progress was made in the development of Alternative Feeds by combining the results of many studies with trout and applying them to other commercially important species including Atlantic salmon, arctic char, cobia, yellowtail, and white seabass and evaluated in extended growth studies. Good growth and feed conversions were observed further proving that aquaculture feeds can utilize high levels of plant ingredients and do not need to depend on fish meal. A trial is currently underway and pilot screening conducted at a commercial trout farm, evaluating fish meal and fish oil free diets. The essential fatty acids for the fish are supplied by algal sources.


4. Accomplishments


Review Publications
Liu, K., Han, J. 2011. Changes in mineral concentrations and phosphorus profile during dry-grind process of corn into ethanol. Bioresource Technology. 102:3110-3118.

Liu, K. 2011. Chemical composition of distillers grains, a review. Journal of Agricultural and Food Chemistry. 59:1508-1526.

Liu, K. 2011. Comparison of lipid content and fatty acid composition and their distribution within seeds of 5 small grain species. Journal of Food Science. 76(2):C334-C342.

Last Modified: 10/16/2017
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