NUTRITION, IMMUNE SYSTEM ENHANCEMENT, AND PHYSIOLOGY OF AQUATIC ANIMALS
Location: Aquatic Animal Health Research
Title: Relationship Between Nutrition and Fish Health
Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: October 30, 2007
Publication Date: November 14, 2007
Citation: Lim, C.E., Aksoy, M., Klesius, P.H., Shoemaker, C.A. 2007. Relationship Between Nutrition and Fish Health. In: II Symposium on Nutrition and Fish Health, November 14-16, 2007, Botucato, Brazil, pgs. 5-20.
Under intensive production systems, proper nutrition plays a critical role in the promotion of good growth, maintenance of normal physiological functions, and resistance to stress and diseases. Diets used are commonly formulated on a cost-effective basis to contain essential nutrients at concentrations to meet or exceed the requirement values to account for losses during processing and storage. However, several factors such as variations in the bioavailability of nutrients of different ingredients, the presence of antinutritional factors/toxins, nutrient interrelationships, and adverse processing and storage conditions may lead to reduced available dietary nutrients resulting in subclinical nutritional deficiencies. Also, to prevent nutritional deficiencies, levels of micronutrients (vitamins and minerals) in high-nutrient, energy-dense diets should be increased proportionally in expectation of additional growth. It has long been recognized that malnutrition predisposes the animals to infectious diseases due in part to impaired immunocompetence as a result of nutritional deficiency. Infections also negatively influence the nutritional state of the host, as most forms of disease result in decreased feed intake, increased nutrient requirements, and decreased nutrient assimilation and utilization efficiency.
In recent years, many investigations have examined the relationship between dietary nutrients (protein and amino acids, lipids and fatty acids, carbohydrates, vitamins and minerals) and disease resistance. Some studies have evaluated only the effects of dietary nutrients on the ability of fish to resist pathogen challenge, while others also examined their effects on non-specific and specific immune responses. Available information, although inconsistent, appears to indicate that deficiencies of dietary essential nutrients result in immunosuppression and increase the susceptibility of fish to infectious diseases. The evidence on the beneficial effects of high levels of antioxidant vitamins E and C on improving immune responses and disease resistance is also inconsistent. The discrepancy between the results from various studies may be attributed to differences in fish species, strain, age/size, nutritional status, degree and duration of nutrient deficiency or excess, interactions between dietary nutrients, feeding management and duration, experimental protocols, environmental conditions, nature of the infectious agents, pathogenicity of microorganisms, and challenge method and dosage used. In the absence of clear-cut information on the beneficial effects 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.