| Nibea albiflora Richardson is an important economical fish in china because of its delicious taste and important commercial value. The cultivation of fish larvae mainly used live food, such as rotifers, Artemia and copepods. In fact, up to now live food act as a key bottleneck for the culture of larvae due to the nutritional imbalance and unstable supply of live food. Until now, the rearing of larvae still depends totally on live food, which account for more than70%of total cost for45days later larvae. Replacement of live food with formulated feeds is an ultimate solution to improve the growth and survival of larvae.The mian contents of this research are as follows:1. The amino acid, free amino acid and fatty acid of the N. albiflora larvae during ontogeny were illustrated. The ontogenesis of digestive enzymes (trypsin, amylases, and alkaline phosphatases) in N. albiflora was determined in larvae between0-45days after hatching (DAH). The amin acid and free amin acid content of the larvae was varied during ontogenesis. The amount of arginine, valine, leucine, isoleucine, lysine was accounted for about70%of total essential amino acids. The amount of aspartic acid, glutamic acid and alanine was accounted for about60%non-essential amino acids. The amount of free amino acids showed a significant decrease during ontogenesis. Fatty acid composition of the feed affected the fatty acid composition and content of the larvae. Docosahexaenoic acid DHA, eicosapentaenoic acid EPA, arachidonic acid ARA, the essential fatty acid of the larvae, was in high level during ontogency.2. The microencapsulated diet was prepared using wet granulation and fluidized bed coating process and the microbound diet was prepared using wet granulation process. Scanning electron microscopy microphotography of the microbound diet showed the appearance was coarse and irregular. Microphotography of the microencapsulated diet showed the appearance with a dense film around the core. The diameters of the microbound diet and microencapsulated diet were in a normal distribution and within a broad size range. The15day after hatching of the larvae was reared for30days fed different diets. There were four treatments:Control:100%copepod; Co-feeding Group:50%copepod+50%microencapsulated diet; Microencapsulated diet Group:100%microencapsulated diet; Microbound diet Group:100%microbound diet. The best growth performance of the larvae was observed from the co-feeding group. The worst growth performance of the larvae was observed from the microbound diet group. The larvae fed the microencapsulated diet showed much greater growth performance compared to the larvae fed the microbound diet.3. Effect of diets microencapsulated with different wall material on growth performance and digestive enzymes of N. albiflora larvae was evaluated. The diets microencapsulated with gelatin, ethyl celluse, zein were prepared using wet granulation and fluidized bed coating process. The characteristic of microencapsulated diets was analyzed and compared. The diameter of most of the microencapsulated diets was between150um and840um. Scanning electron microscopy microphotographs showed the appearance of the microencapsulate diet was a dense film. The inclusion efficiency of the diets microencapsulated gelatin, ethyl celluse, zein was95.4%,95.6%,95.8%respectively, the lipid encapsulation efficiency was72.6%、76.5%、64.3%respectively, the nitrogen retention efficiency of was53.5%、62.3%、54.6%respectively. The larvae of N. albiflora15days after hatch were fed different diets for30days. The wet weight, total length, survival of the larvae from Gelatin Group was significantly higher than those from Ethyl cellulose group, Zein group. The trypsin and alkaline phosphatase activity of the larvae was highest from Gelatin group, the trypsin, amylase, alkaline phosphatase was the lowest from ethyl cellulose group. These results indicated that the gelatin is as wall material for preparing microencapsulated diet more suitable for larvae than ethyl cellulose and zein. |
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