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Background
Growth and development, and nutrition are imperative for all animal production. These components form the basis for economic production of high quality and healthy aquaculture products for the American public and for export. Efficient growth and development is dependent upon an adequate supply of essential nutrients. Altering dietary nutrients and energy, and feeding management can have a direct impact on the growth and development at different life stages, disease resistance, production efficiency, quality and quantity of final product as well as waste production. Nitrogen, phosphorus and organic substances from unconsumed and undigested feed as well as metabolic wastes are the major sources of environmental pollution. These compounds, at high concentrations, may lead to toxicity, health risk and growth depression. Moreover, alternative sources of feed ingredients must be found to reduce the current heavy dependence of the aquaculture feed industry on fish meals and oils. Thus, appropriate nutrition to lower feed costs, improve production efficiency, reduce disease-related production losses, improve the quality of final product and reduce environmental impacts is fundamental for sustaining the growth and competitiveness of the U.S. aquaculture industry.
Vision
Develop efficient diets and feeding practices that optimize growth and development, enhance production efficiency, product quality, disease resistance, and minimize environmental impacts.
Mission
To develop cost-effective feeds and feeding strategies for commercially important aquaculture species that maximize nutrient utilization, reduce disease-related production losses and reduce the impact on the environment arising from aquaculture.
Impact
Increasing production efficiency and providing healthy and nutritious food products from aquaculture species raised in culture systems that are environmentally sustainable.
Linkages
Other USDA-ARS National Programs: 101 Food Animal Production; 103 Animal Health; 105 Animal Well-Being and Stress Control; 107 Human Nutrition; and 206 Manure and Byproduct Utilization.
Other Agencies and Departments: U. S. Colleges of Agriculture and State Agricultural Experiment Stations.
Private Sector: American Feed Industry Association; American Fish Farmers Associations
Problems to be addressed
a. Regulating Feed Intake
A major controlling factor of growth across species is feed intake. Feed costs represent the primary economic input into aquaculture production systems. Metabolic and sensory factors affect short-term feeding behavior. Long-term feeding behavior is controlled by the animal with its attempt to adjust to a defined equilibrium within its environment. Understanding the mechanisms involved in regulating feeding behavior and appetite will lead to more efficient production of aquaculture species.
Goals
1. To understand the mechanisms regulating feed intake in order to optimize the utilization of feed resources.
2. Improve energy balance of commercially important aquaculture species at different phases of production.
Approaches
1. Elucidate roles of dietary constituents and additives (such as hormones and growth promoters), nutritional metabolites in regulating feed intake.
2. Identify hypothalamic factors that control physiological systems regulating feed intake.
3. Identify physiological processes that control feed intake at various life stages of commercially important aquaculture species.
Outcomes
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Improved efficiency of feed use by commercially important aquaculture species at various phases of production.
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Increased knowledge and understanding of mechanisms involved in regulating feeding behavior and appetite will be developed.
ARS Locations
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Stoneville, MS
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Stuttgart, AR
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Leetown, WV
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Hilo, HI
b. Tissue Growth and Development
Improved growth and development are vital for the sustainability and profitability of the aquaculture industry. Optimum growth performance and efficiency have limited value if product quality is not acceptable to consumers. The impact of tissue development and growth, and nutrition on flesh quality and composition is not completely understood. Knowledge of genetic, environmental, and nutritional factors that control development and growth of muscle, fat, and reproductive tissue is needed to develop practical methods for improving flesh quality and composition, and reproductive performance.
Goals
1. Understand the physiological and environmental conditions that enhance expression of growth and reproductive potential of aquaculture species.
2. Alter characteristics of flesh quality of commercially important aquaculture species to meet consumer preference and improve nutritional value.
3. Determine the genetic and physiological basis for development and differentiation of adipocyte precursor, skeletal muscle cells, gonadal and epithelial cells.
4. Identify tissue specific bioregulatory mechanisms for adipose, bone, muscle, and reproductive tissue growth, and function.
Approaches
1. Investigate neural, and endocrine mechanisms affecting growth and composition at animal and tissue levels.
2. Use in-vivo and in-vitro models to understand and control developmental processes as they affect productivity and product quality.
3. Characterize growth- and reproductive-related endocrine functions during tissue wasting that accompany infectious diseases.
Outcomes
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Increased growth rate and decreased culture period of various stages of production cycles.
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Produced aquaculture products with improved sensory attributes and nutrient composition for consumers.
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Increased reproductive performance, and gonad quality of aquaculture species.
ARS Locations
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Stoneville, MS
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Leetown, WV
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Stuttgart, AR
c. Sustainable sources of nutrients
Aquaculture feeds, especially those for carnivorous species, are heavily dependent on fish meal and fish oils to meet their critical protein and lipid requirements. The global supply of fish meal will likely remain static or decline because captured fisheries have reached maximum sustainable yields. There is also increasing competition among consumer segments for these products. Thus, for the U.S. aquaculture industry to expand and remain competitive, cost-effective, sustainable sources of protein and oil must be identified or developed.
Goals
1. Identify and develop alternative sources of ingredients of economical importance to the U.S. to replace or reduce fish meal and fish oils in aquaculture diets.
2. Develop nutritionally efficient diets using alternative sources of ingredients.
Approaches
1. Evaluate physical, biochemical and biological characteristics of alternative protein and lipid sources as replacements for fish meal and oil in diets of aquaculture species.
2. Determine the nutrient bioavailability of alternative feed ingredients for commercially important aquaculture species.
3. Evaluate the efficiency of diets containing alternative ingredients in terms of pellet quality, nutrient utilization, feed consumption, growth performance, health, meat quality, production efficiency, and water quality.
Outcomes
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New sustainable sources of ingredients as replacements for fish meal and oils in aquatic animal diets.
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Consistent supply of low-cost, nutritionally efficient diets for various life stages of aquaculture species will be developed.
ARS Locations
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Auburn, AL
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Aberdeen, ID
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Stuttgart, AR
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Hilo, HI
d. Nutrient Use and Feed Evaluation
Changes in dietary nutrients and energy can have a profound impact on growth and development, reproductive success, composition of growth and carcass quality, disease resistance, and waste accumulation. Individual feed ingredients, whether traditional, novel and/or genetically-modified, greatly impact these characteristics though few ingredients have been evaluated for their potential nutrient bioavailability. Knowledge of feeding strategies to increase nutrient utilization and assimilation and decrease waste output are important for sustainable and profitable aquaculture production. Furthermore, the impact of diet alteration on product quality and how this relates to consumer preferences must be evaluated.
Goals
1. Develop diets based on ingredient nutrient bioavailability to conform to the nutrient and energy requirements of commercially important aquaculture species at different life stages reared in different culture systems.
2. Develop feeding practices and strategies to improve nutrient retention, increase feed conversion efficiency, improve product quality, and reduce wastes.
3. Establish feed manufacturing processes to improve feed palatability, pellet quality and nutrient availability, inactivate anti-nutritional factors, and reduce environmental impacts.
Outcomes
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Aquaculture diets that optimize growth and development, provide desirable flesh quality, and increase production efficiency with minimal environmental impacts.
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Feeding management strategies for various production systems that enhance or optimize production efficiency with minimal environmental impact will be developed.
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Optimum feed and ingredient processing methods and conditions that enhance pellet physical characteristics, palatability, and nutrient bioavailability.
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Knowledge and strategies of nutritional modulation of metabolic processes in aquaculture species will be realized.
ARS Locations
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Hilo, HI
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Auburn, AL
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Aberdeen, ID
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Stuttgart, AR
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Leetown, WV
e. Interaction of Gene Regulation and Nutrition
Current state of knowledge on gene regulation for growth and metabolism in aquaculture species is limited. Nevertheless, several research institutions have devoted considerable resources and efforts to genetically manipulate stocks of aquaculture species to improve growth and development. Genes responsible for regulating these physical traits must be better understood. Nutrient requirements must be determined and met to realize improved genetic potential. Feeding practices and strategies to deliver nutrients to optimize production while minimizing nutrient losses to the environment must be developed. A comprehensive understanding is required of the metabolic or physiological functions that limit production potential.
1. Improve understanding of functional genomics associated with growth and development and
2. nutrition.
3. Alleviate metabolic or physiological limitations restricting performance.
4. Optimize animal nutrient efficiency to maximize conversion of nutrients to food products and
5. balance environmental impacts with costs of production.
Approaches
1. Determine factors limiting maximal animal responses and identify metabolic or physiological functions controlling nutrient use.
2. Examine changes in gene expression in response to alterations in feed nutrients.
3. Identify mechanisms by which nutrient components affect or regulate genes involved accretion of fat and lean muscle mass.
4. Explore the genetic basis for nitrogen and phosphorus metabolism and the potential to manipulate intake/output relationships in N and P metabolism.
5. Elucidate changes in dietary levels of nutrients and feeding strategies to optimize growth, nutrient retention, health, carcass quality, and minimize environmental impacts.
f. Interactions Affecting Reproduction
Reproductive processes are affected by numerous nutritional factors such as diet composition, regulatory metabolic hormones, and body contents of certain nutrients. Changes in diet affect pituitary hormone secretions and reproductive performance. Understanding of basic regulatory cell interactions affecting gonadal development, maturation and spawning, and gonadal and larval quality, as influenced by changes in dietary nutrient and energy profiles, and feeding strategies, is needed to develop effective maturation diets and refine feeding systems and aid in cost effective management of broodstock and seed production.
Goals
1. Improve diets formulations and feeding management strategies to enhance reproductive performance, and improve gonadal and larval quality of commercially important aquaculture species.
2. Improve understanding of nutritional effects on regulatory cells affecting gonadal development, maturation and ovulation.
Approach
1. Determine requirements and quantify effects of nutrients such as vitamins, minerals, fatty acids and amino acids on components of reproductive efficiency, and gonadal and larval quality.
2. Evaluate nutritional effects on neuro-endocrine pathways regulating gonadal function and behavior.
3. Determine the impact of pre-spawning and post-spawning nutritional strategies and culture management on reproductive efficiency.
Outcomes
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Nutritional management systems and culture practices that enhance or maximize reproductive efficiency will be developed.
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Increased knowledge of nutritional modulation of cellular functions affecting reproductive physiological pathways in commercially important aquaculture species.
ARS Locations
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Stoneville, MS
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Stuttgart, AR
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Leetown, WV
g. Effective Probiotics
As with terrestrial monogastric animals, aquaculture species also host microbial populations in their gut that can influence the efficiency of nutrient utilization. Regional differences in types and availability of feeds and the introduction of new, alternative feed ingredients with improved nutritional properties have increased options for formulating rations to improve production. There is a paucity of information on the interactions of these feeds and microflora in the gastrointestinal (GI) tract of aquaculture species. Understanding how these interactions affect digestibility, digestion kinetics, and nutrient absorption is important for optimizing feed efficiency.
Goals
1. Develop strategies to optimize populations of specific, beneficial microbial species.
2. Elucidate the biological and environmental factors affecting composition of microbial species of the GI tract and growth efficiency of GI tract microorganisms.
3. Determine efficiency of microbial species to improve water quality and digestibility of various feed components under different production systems and environmental conditions.
Approach
1. Characterize interactions among microbes and their degradation characteristics and efficiencies associated with varying production conditions.
2. Identify gut microbial species and their ecological significance in the GI tract of aquatic animals raised in various production systems.
3. Identify microbial species instrumental in degradation/digestion of plant feedstuffs and in facilitating nutrient passage from the gut.
4. Characterize gut microbes of aquaculture species through successive generations and determine the effects of diets and environmental parameters on microflora.
5. Determine the impact gut microflora on nutrient excretion and how the modification of the existing microflora affects nutrient utilization, nutrient excretion, and environmental quality.
Outcome
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Nutritional systems to enhance and maximize efficiency of nutrient use through optimization of relationships between endogenous gut microflora and diets.
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Production systems to improve water quality, growth and product quality will be developed.
ARS Locations
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Auburn, AL
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Stuttgart, AR
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New Orleans, LA
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Hilo, HI
h. Immune System Enhancement (Nutrients and Immunostimulants)
Diseases cause considerable losses to aquaculture production. Currently only a limited number of therapeutics/chemicals are approved for disease treatments. These treatments are often ineffective, costly, and result in product and environmental contamination. A better alternative is to improve the disease resistance by enhancing the immune response. It is commonly known that nutrition is a key factor affecting aquatic animal health. A deficiency or excess of most, if not all, dietary nutrients has profound effects on infection and survival, largely through effects on host immune function. Other factors such as nutrient bioavailability and interactions, the presence of immunostimulants and/or toxins, and feeding management also influence on the immune system function and disease resistance of aquaculture species.
Goals
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Elucidate the effects and modes of actions of dietary nutrients and immunostimulants, and identify natural compounds in feed ingredients capable of enhancing immune system function and disease resistance in aquaculture species.
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Delivery methods and optimum concentrations of nutrients/immunostimulants to enhance innate immunity and disease resistance will be identified.
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Feeding regimens and feeding strategies will be evaluated in relation to environmental parameters and life stages on immune response and disease resistance.
Approaches
1. Identify and evaluate the roles of dietary levels of nutrients and their interactions on immune responses and disease resistance at various life stages of aquaculture species.
2. Evaluate role and potential sources of immunostimulants, their dosages, route of administration and duration of feeding on immune functions and disease resistance.
3. Determine the effects of alternative sources of ingredients and identify compounds responsible in improving immunity and disease resistance.
4. Evaluate the effects of feeding strategies in relation to environmental parameters on immune responses and diseases resistance.
5. Conduct bacterial bioassays to screen natural and natural product-based compounds to identify promising leads for novel therapeutics and immunostimulants.
ARS Locations
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Auburn, AL
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Stuttgart,AR
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Oxford, MS
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