NUTRITION, IMMUNE SYSTEM ENHANCEMENT, AND PHYSIOLOGY OF AQUATIC ANIMALS
Location: Aquatic Animal Health Research
Title: NUTRITION, IMMUNE RESPONSE AND DISEASE RESISTANCE IN FISH
Submitted to: Animal Nutrition Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: November 1, 2005
Publication Date: November 7, 2005
Citation: Lim, C.E., Aksoy, M., Klesius, P.H. 2005. Nutrition, immune response and disease resistance in fish. 1st Simposio De Nutricao E Saude De Peixes. Botucatu, Sao Paulo, Brazil. November 7-9, 2005. p. 46-83.
It is common knowledge that, under intensive aquaculture production, good nutrition plays a key role in promoting good growth, sustaining health, and maintaining the ability of fish to withstand stress and resist disease-causing agents. Fish, like homeothermic vertebrates, defend against infectious agents by a variety of immunological mechanisms which can be grouped into innate (natural or nonspecific) and acquired (specific) immunity. Nutritional strategies to reduce stress, and improve immune responses and disease resistance in terrestrial animals have been extensively studies but limited information is available for aquaculture species. In recent years, however, great interest has been toward understanding the interactions between dietary nutrients (protein and amino acids, lipids and fatty acids, carbohydrates, vitamins and minerals), immune responses and resistance of fish to various infectious diseases. Among these nutrients, dietary levels and sources of protein, lipids and carbohydrates have received limited attention. Micronutrients such as vitamins C and E and iron have been critically evaluated. Evidence from a limited number of studies indicates that antinutritional factors/toxic substances present in plant feedstuffs and mold toxins may have profound effects on the immune system function and the susceptibility of fish to stress and pathogenic microorganisms. Feeding management has also been shown to have a significant effect on disease resistance and survival of fish during disease outbreaks. Available information appears to indicate that deficiencies of dietary essential nutrients and the presence of high levels of antinutritional factors and/or toxins are immuno-suppressive. However, evidence on the beneficial effect of high levels of certain dietary nutrients and a brief period of withholding feed on the resistance of fish against infectious microorganisms is inconsistent. The discrepancy between the results from various studies may be attributed to differences in fish species, strain, size and nutritional status, composition and nutrient content of the basal diet, feeding management and duration, experimental design, environmental conditions, pathogenicity of microorganisms, and challenge method and dosage used. In the absence of clear-cut information on the beneficial effect of nutritional factors on immune responses and disease resistance in fish, proper feeding practices and sufficient levels of essential nutrients necessary for optimum growth and sustaining health is recommended.