DEVELOPMENT AND EVALUATION OF METHODS TO DELIVER WATER-SOLUBLE MICRONUTRIENTS TO MARINE FISH LARVAE

In this proposal we apply for a Leiv Eiriksson grant to cover housing, travel and some running costs in connection with a sabbtical at NIFES for prof. Chris Langdon from Oregon State University, USA. Prof. Langdon is a leading scientist in fish larval bio logy with production of formulated feeds for marine fish larvae as his speciality. This topic is also investigated at NIFES and one of our PhD students visited Prof. Langdon's lab this year on a Leiv Eiriksson grant. A major problem with these feeds is a high leakage rate of watersoluble nutrients due to the small size of the particles. Prof. Langdon is developing techniques to prevent this leakage, which is the focus of this application. We will also look at the nutritional implications of using these te chniques. Watersoluble micronutrients will be encapsulated in lipid spray beads (LSB). The nutrients that will be investigated are iron, iodine, two watersoluble vitamins and free amino acids. The impact of the lipid material and the encapsulated micronu trient on encapsulation efficiency and leakage rates will be investigated. The LSB will then be embedded into larger complex particles which contain the macronutrients. The encapsulation in LSB will prevent leakage of watersoluble nutrients but may reduc e the availability of the nutrients to fish larvae. This problem will be investigated by tube feeding individual larvae with labelled free amino acids ether incapsulated or not in LSB. Finally we will aim at conducting feeding experiments with LSB contain ing micronutrients, embedded in complex particles. The uptake of nutrients in fish larvae will be monitored together with fish performance .