Delivering bioactive compounds to fish larvae using microencapsulated diets

Abstract

The efficient delivery of nutrients and hormones has special relevance to the development of rearing technologies for fish larvae and juveniles. The main aim is to find an effective and measurable way to administer them into the body of small aquatic animals. In this study, three different compounds (hormones, amino acids, and vitamins) were incorporated into protein-walled microencapsulated diets. Specifically these microencapsulated diets were examined for (a) the kinetics of incorporation of estradiol in Sparus aurata larvae, (b) absorption and leaching patterns of the free amino acids (FAA), and (c) growth results and tissue incorporation of vitamins in relation to the supplementation of vitamin C in larvae of S. aurata and Solea senegalensis. The efficiency of inclusion was relatively low, but the capsules were able to retain enough of these compounds when immersed in water and to deliver them into the digestive tract of the larvae. There are noticeable differences among the nominal amount of a given substance in the ingredient mixture, the actual amount in the microparticle and the amount delivered in the larval gut. It is therefore necessary to examine carefully whether the ingredient is reaching the digestive tract for achieving suitable conclusions in nutritional studies. These results indicate the applicability of these microencapsulated particles in nutritional studies of small aquatic animals.