ATLANTIC SALMON SMOLTS HAVE A HIGHER DIETARY VALINE REQUIREMENT THAN FRY

摘要

The minimum requirements for indispensable amino acids (IAA) in the diet of Atlantic salmon have hardly received any scientific attention. This is disturbing, taking into account the huge production of salmon which, in Norway, totaled 1.2 million T in2012. Dietary changes during the last decades have turned farmed salmon from being a piscivore into almost a vegetarian. Such radical changes should have elicited more studies on amino acid requirements of salmon. During the last years, our research group has expanded traditional amino acid requirement studies from use of dose-response trials (RDR) to also include requirements for maintenance and the efficiency of utilization of amino acids for growth above maintenance (requirement by ration level; RRL). With the latter design, one diet is fed at different levels and growth is determined. This design is not new, but we have expanded it to include evaluations of all IAA in the same trial. We have used this combined approach in our studies of the lysineand threonine requirements for salmon smolts. The major advantage of this combined design is that it reveals more of the dynamics in amino acid metabolism, and this is done in a quantifiable manner. The present trial describes the valine requirements ofsmolts during the first phase in seawater.