養殖ハマチの血液・体成分に及ぼすそう類添加飼料の効果

Abstract

The effect of algae as feed supplementary was determined on yellow tail Seriola quinqueradiata in terms of serological parameters and proximate composition of the dorsal muscle. Fish of 144g in body weight were reared for 60 days in floating nets. Control group was fed on sand lance Ammodytes personatus.One percent of hot water-extract from Chlorella vulgaris (Chlorella-extract group) or 0.5% of kelp Laminaria digitata (kelp meal group) was supplemented to the above basal diet (sand lance). The supplementaries had no effect on body weight gain or feed conversion efficiency. The kelp meal depressed the lipid, non-protein nitrogen, and amino nitrogen levels in the serum, and elevated the muscle lipid level. Chlorella-extract, however, did not cause significant alteration in serum constituents and proximate composition of the muscle.After 60 days of feeding, the fish were kept in indoor tanks without feeding for 23 days. Body weight loss was not significantly distinct among the 3 groups. Nevertheless, the serum lipid and nonesterified fatty acid levels were characteristically changed under the starvation period in response to the dietary regimen. The muscle lipid loss was higher in the kelp meal group than the control group. Furthermore, the suppression of breakdown of muscle protein was found in the Chlorella-extract group and the kelp meal group.These results showed that the kelp meal contributed to accelerate the lipid deposition to the muscle and to mobilize the lipid to energy. The importance of algae supplement in yellow tail, was discussed in relation to improvement of lipid metabolism which had a close connection with the health condition of the fish.