Growth performance, innate immune responses and disease resistance of fingerling blunt snout bream,Megalobrama amblycephalaadapted to different berberine-dietary feeding modes
A 8-week feeding trial was conducted to evaluate the effect of different berberine-dietary feeding modes on growth, non-specific immune responses and disease resistance of blunt snout bream, Megalobrama amblycephala. Fish (average initial weight 4.70 ± 0.02 g) were fed two fat levels (5% and 10%) diets in three berberine-feeding modes (supplementing 50 mg/kg berberine continuously, two-week or four-week intervals) with four replicates, respectively. Then, fish were challenged by Aeromonas hydrophila and mortality was recorded for the next 96 h after feeding trial. The results showed that different feeding modes of berberine significantly influenced growth, innate immunity and antioxidant capability of fish. Fish fed normal diet with 50 mg/kg berberine at two-week interval mode reflected remarkably (P < 0.05) high weight gain (WG). Plasma TC and TG contents were significantly (P < 0.05) decreased. The lysozyme (LYZ) activities, complement component 3 (C3) and complement component 4 (C4) concentrations were significantly (P < 0.05) increased. Fish not only exhibited relatively low hepatopancreas malondialdehyde (MDA) and lipid peroxide (LPO) contents, but also significantly (P < 0.05) improved superoxide dismutase (SOD) and catalase (CAT) activities. Fish mortality after challenged by Aeromonas hydrophila was decreased. Same results were also presented in fish fed high-fat diet with 50 mg/kg berberine at two-week, four-week intervals or continuous feeding modes. Based on fish healthy improvement and feeding cost saving, blunt snout bream fed normal diet with 50 mg/kg berberine at two-week interval or fed high-fat diet with berberine at two-week or four-week intervals were optimal feeding mode, respectively.