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Until some years ago, whenever animal farming was hit with a new pathogen or a disease problem, expectations were that one or more of the animal health companies would find a solution in the form of a vaccine, antibiotics or another chemotherapeutic agent. A more comprehensive approach to combating disease problems that combines genetics, nutrition, biosecurity and good management practice is advocated today. This approach is in response to the limitations os the chemotherapeutic route to disease management and to the advancements in knowledge about the role of other factors in animal health.

Feed manufacturers, rather than animal health companies, have long been expected to deliver animal health solutions in aquaculture. This is because traditional animal health companies have shown persistent reluctance to commit resouces to the aquatic animal health segment due to its small size. Furthermore, aquaculture producers depend on feeds to deliver health products to aquatic organisms because it is often the only logistically feasible delivery tool. This dependence presents oppurtunities for the feed manufacturers to develop and launch innovative products and create market recognition. So, we felt the need to periodically update our readers on developments in nutrition related to aquatic animal health. This issue will be the first in a series focusing on the topic.

To renowed nutritional immunologists, Drs. Viviane Verlhac and Viswanath Kiron, open the issue with a concise review of the topic. Their article educates nutritionists the basics of aquatic animal immune system and the nutrients and other dietry components that play a role in improving animal health. They also outline the current knowledge on measuring immune system's responses to various immunomodulators. The latter is important in feed development as nutritionists and formulators need to assess and quantify the effect of potential immunmodulators on animal health and production. The revies is followed by articles on specific animal health products: nucleotides, probiotics, prebiotics and fucoidans, a set of immunomodulators derived from brown seaweed.

Knowledge on the general mechanisms of nutrients and other dietry components that play a role in animal health as well as specific products (including those that appear in this issue) is still evolving. Molecules such as nucleotides and glutamine, which were previously considered dispensable in the diet, are now regarded as "conditionally essential" - nutrients required in the diet at early and/or reproductive phase of life or during periods of stress or disease. Too much of some nutrients in the diet such as n-3 polyunsaturated fatty acids and iron may have as much negative impact on the immune system performance as too little of them. There is consensus among nutritionists that nutrient requirements of animals would have to be eventually redefined on the basis of immune system performance in addition to growth and other production parameters. The young science of nutritional immunology has much to offer to aquaculture production in the coming years.

Comments are welcome from our readers on the contents of this issue. Please tell us what you see as critial aspects in the development of practical applications from the findings of scientific research in nutritional immunology.

Victor Suresh
victor@feedware.com