Nutrient delivery to larval penaeid shrimp

Abstract

Nutrient delivery to aquatic larvae must be controlled before their nutrition can be critically studied. Conventional feed particles and microcapsules for larval shrimp have poor water stability and/or poor nutrient retention. When compared to live food organisms, inert feeds do not promote normal growth of larval shrimp. Initially, Penaeus vannamei Boone larvae were reared on a microbound feed reported to be highly successful in nutrition research. Although responses to feed-formula modifications were significant, test shrimp weighed about 60% less than live-food controls. Subsequently, a novel feed that retained vitamins within lipid-wall microcapsules, and capsules plus feedstuffs within calcium alginate microparticles (ca. 70 - 1000 μm), was researched. High feedstuff content improved particle water stability. Bioavailability of encapsulated molecules was evidenced by photomicrography of dye marker released in larval shrimp guts and by 14C-label uptake from 14C-glucose. Supplementation of live algae with prototype feed improved larval-shrimp growth, but effects of encapsulated vitamins were not detected, probably because macronutrients, rather than micronutrients, were limiting growth. Finally, test feeds with different amino acid profiles were fed to postlarvae and oxidative glutamate dehydrogenase (GDH) activity in crude extracts was measured. Feed protein quality was inversely related to GDH activity. Herein are the first reports of water-soluble nutrient delivery to larval shrimp, of a new class of larval feed, and of dietary protein quality effects on crustacean GDH activity. Compartmentalized feed particles comprise a tool for studying nutrition of aquatic animals and have better potential to replace live food organisms in aquaculture than do any other types of prepared feed researched and described to date.