Acceptability of complex microencapsulated diets by striped bass (Morone saxatilis) larvae

The acceptability of two microencapsulated diets (casein-walled complex mic rocapsules, CWC, and CWC containing water and lipid soluble fractions of Ar temia, MCWC) by striped bass larvae, from 7 to 21 days posthatching (DPH), was tested. These two microencapsulated diets were fed to striped bass larv ae exclusively (CWC or MCWC alone, 1.1 mg/larva/day) or as partial replacem ent of live food, Artemia nauplii (two nauplii/ml + MCWC, 1.1 mg/larva/day) . Controls were unfed larvae and larvae fed with a full ration of Artemia ( five nauplii/ml) or 40% ration of Artemia (two nauplii/ml). The ingestion { (number of larvae with food items in the gut divided by total number of lar vae examined) X 100%} of CWC and MCWC by larvae were 42% and 75%, respectiv ely at 7 DPH, while the ingestion in groups fed with full, or 40% ration Ar temia, and fed 40% Artemia plus MCWC were nearly 100% (96%-98%). On 14 DPH, the ingestion by the larvae fed CWC and MCWC increased markedly, reaching 100%. The survival of the larvae fed solely CWC and MCWC were 44% and 54% r espectively, lower than the two controls fed full or 40% ration of Artemia and the group fed MCWC + 40% Artemia. The survival of the later three group s ranged from 72 to 78%. All the unfed larvae died by 19 DPH. The larvae fe d a full ration of Artemia had the highest mean wet weight and total length . Supplementing the group fed 40% ration Artemia with MCWC slightly improve d the growth of the larvae compared to the nonsupplemented group. At the en d of the experiment, larvae in that group had significantly greater wet wei ght gain and total length than the nonsupplemented group. The results of th is study revealed that a complex-protein walled capsule is readily ingested by striped bass larvae at first feeding. Potentially, the complex-protein microencapsulated diet containing Artemia extracts can be used as partial r eplacement of live food. However, to achieve such a goal, study is needed t o improve its nutritional quality and digestibility, in particular. (C) 199 9 Elsevier Science B.V. All rights reserved.