Evaluation of calcined oyster shell waste as a sustainable dietary calcium source for juvenile black rockfish (Sebastes schlegelii): Effects on growth performance, digestive enzyme activity, antioxidant defense, and innate immune responses

초록

This study evaluated the effects of calcined oyster shell (COS) waste as a sustainable alternative calcium (Ca) source in diets of juvenile black rockfish (Sebastes schlegelii) on growth performance, physiological stability, antioxidant defense, and innate immune responses. A total of 720 fish (initial body weight 2.0 +/- 0.01 g) were randomly distributed into 12 tanks and fed one of four experimental diets for 8 weeks: a positive control with a conventional Ca source (PCa), a low-Ca basal diet (LCa), and basal diets supplemented with 5 g/kg (COS5) or 10 g/kg (COS10) COS. Growth performance was reduced, and immune indicators were suppressed in fish fed LCa compared with those fed PCa. COS10 significantly improved weight gain (WG) and feed efficiency (FE) relative to the LCa group, reaching values comparable to those of the PCa group. Serum immunoglobulin M levels were markedly lower in fish fed LCa but were higher in the COS10 group. Similarly, interleukin-1 contents were comparable in the COS10 and PCa groups, but were lower in the LCa and COS5 groups. Antioxidant parameters, including SOD activity, were also higher in the COS10 than in the LCa group. Whole-body proximate composition and plasma Ca concentrations were not significantly affected by diet. These findings indicate that supplementation of the diet with 10 g/kg COS can support growth performance and immune responsiveness under low dietary Ca conditions, highlighting its potential as a sustainable alternative Ca source in aquaculture feeds.

키워드