BIOCHEMICAL AND ENZYMATIC CHARACTERIZATION OF DECAPSULATED CYSTS AND NAUPLII OF THE BRINE SHRIMP ARTEMIA AT DIFFERENT DEVELOPMENTAL STAGES

Decapsulated Artemia cysts were used to study the factors which induce the superior performance of live organisms as food for fish larvae. T he biochemical composition, the in vitro protein digestibility, and th e total proteolytic and trypsin activities in cysts and nauplii of Art emia were determined at different developmental stages as a function o f incubation time. Six different incubation times were studied: 1, 6, ii, 16, 21 and 25 h of development, which cover cyst and early nauplii stages. The individual dry weight of Artemia decreased through develo pment. The individual protein and lipid content (mu g ind(-1)) remaine d constant during development until the time of hatching after which t hey decreased slightly. However, no significant incubation effect was found. Small changes in amino acid and fatty acid composition were fou nd during development, but is assumed that they are too small to be of nutritional importance to fish larvae. No major changes were observed in protease activities measured at acid and alkaline pH during the fi rst 25 h of development. From the alkaline proteases, no significant c hange in trypsin activity was detected during cyst and early nauplii d evelopment. From the point of view of exogenous enzyme contribution to fish larvae, there seems to be no difference whether feeding decapsul ated cysts or newly hatched nauplii, since no difference in qualitativ e protease composition was found during the first 25 h of Artemia deve lopment. The relative contribution of Artemia proteases to the digesti on of food by fish larvae is discussed. (C) 1998 Elsevier Science B.V.