Effects of different wall materials of the microencapsulated diets on the growth and digestive enzyme activity of Nibea albiflora Larvae

In this study, we evaluated the effects of different wall materials of microencapsulated diets on the growth and the digestive enzyme activity of N. albiflora larvae. Three groups of diets were microencapsulated with gelatin, ethyl celluse, and zein. The microencapsulated diets were prepared with wet granulation and fluidized bed coating process. More than 50% of the microencapsulated diets had diameters between 250 m and 590 m. Scanning electron microscopy microphotographs showed that the surface of the microencapsulated diet was covered by a dense film. The inclusion efficiency of the gelatin, ethyl celluse, and zein groups was 95.4%, 95.6% and 95.8%, respectively; the lipid encapsulation efficiency was 72.6%, 76.5% and 64.3%, respectively; the nitrogen retention efficiency was 53.5%, 62.3% and 54.6%, respectively. A 30-day feeding experiment was conducted with the larvae at DAH 15. At DAH 20, the larvae were weaned from copepods to the experimental diets. The wet weight and total length of larvae from the gelatin group and the zein group were significantly larger than those from the ethyl cellulose group (P0.05). There was no significant difference in the survival rate between the groups. The trypsin activity of the larvae from the gelatin group was significantly higher (P0.05) than the ethyl cellulose group and the zein group. There were no significant differences in the amylases activity and the alkaline phosphatases activity between the groups. Therefore compared to ethyl cellulose and zein, gelatin should be more suitable for the wall material of the microencapsulated diets for N. albiflora larvae.