Roles of vitamins in bone development and mineral metabolism

Bone disorders are recurrently observed with high frequencies in intensive farming of salmonids, as also observed in other husbandry. Nutrition, water temperature and fast growth have been identified or suspected as risk factors. For the production of salmonids both the feed composition and feed ingredients used have changed dramatically during the last 15 years. The nutrient compositions has changed towards increased lipid and energy contents and reduced protein and carbohydrate contents. As a consequ ence of the worldwide expanding farming activity with increased need for feed resources, the marine feed ingredients are more variable in types of fishmeal and oils, and there is an increasing use of vegetable protein and lipid sources. Changes in feed co mposition and the increased feed intake at fast growth have increased the risk for vitamin deficiencies (vitamin K) and toxic responses (vitamin D and A), with may result in bone disorders. Increased basic knowledge on the roles of the lipid soluble vita mins in bone tissue development and formation is therefore essential, both from ethical and economical points of views. As fishes seem to differ from terrestrials on vitamins A and D metabolism, the obtained knowledge in this strategic program will also b e of comparative interest. The program includes establishment of in vitro/in situ models and the use of modern technology and analyses within morphometry, nutrient and mineral analyses, endocrinology and cellular functions and responses. The program will be coordinated towards ongoing activities at the collaborative institutes, as well as an ongoing SIP at the Institute of Marine Research in Bergen. Three PhD students will be educated, with exchange and transfer of knowledge between the partners.