A multivariate study on the effects of dietary vitamin K, vitamin D3 and calcium, and dissolved carbon dioxide on growth, bone minerals, vitamin status and health performance in smolting Atlantic salmon Salmo salar L.

Bone deformities represent an increasing, unsolved problem for intensive farming of Atlantic salmon, Salmo salar L. To increase insight into nutritional and environmental impacts on bone mineralization, 16 groups of Atlantic salmon parr were fed diets with different levels of menadione sodium bisulphite (MSB), vitamin D-3 , and calcium (Ca), and exposed to different levels of dissolved carbon dioxide (CO2 ) based on a multivariate factorial design (2(4) ). The composition of the experimental diets was either a high or low level of each of the design variables. In addition, four groups (centre points) were fed a diet with intermediate levels of all dietary parameters and exposed to an intermediate level of dissolved CO2 to record the variation among tanks. After 6 weeks in fresh water, fish were marked according to group, transferred to a common net pen in sea water and fed commercial feed for another 11 weeks. High levels of CO2 decreased fish growth both in fresh water and sea water. No visible bone deformities were recorded at any time. Dry matter, protein and ash compositions of bone and concentrations of Ca, phosphorus (P) and magnesium (Mg) in bone were not significantly affected by any of the design variables. Minor effects were observed in clinical parameters recording health performance, stress and plasma Ca homeostasis. The mean level of vitamin D-3 measured as cholecalciferol in fish organs increased significantly during the freshwater period and reflected dietary vitamin D-3 , whereas the level decreased when fish were fed commercial feed in sea water. The level of menaquinone in liver increased significantly in response to high dietary levels of MSB, indicating that dietary MSB was converted to menaquinone in salmon.