EFFECT OF DIETARY LIPID LEVELS ON SERUM BIOCHEMICAL INDICES, IMMUNE RESPONSES AND ANTIOXIDANT CAPABILITY OF JUVENILE FURONG CRUCIAN CARP (FURONG CARP♀ RED CRUCIAN CARP♂)

To investigate effects of dietary lipids on serum biochemical indices, immunity, and antioxidant capability of juvenile Furong crucian carp (Furong carp♀ red crucian carp♂) mean initial body weight, (2.040.01) g, five isonitrogenous experimental diets were formulated with increasing lipid levels (2.50%, 4.39%, 6.61%, 8.42% and 10.81% lipid) using fish oil as the lipid source to feed triplicate groups of fish for 60 days. The results showed that with the increase of dietary lipid level, weight gain rate (WGR) and protein efficiency ratio (PER) significantly increased and then decreased, and the maximum of WGR and PER were found in the 6.61% lipid group (P0.05). The feed conversion ratio (FCR) showed the opposite trend. Dietary lipids significantly increased serum total cholesterol (CHO) and globulin (GLB) contents, but significantly decreased total protein (TP) and albumin (ALB) content (P0.05). Dietary lipids have no effect in high density lipoprotein cholesterol (HDL-C) and triglyceride (TG) content (P0.05). The immunoglobulin M (Ig M) content, serum superoxide dismutase (SOD), hepatic SOD activity and total antioxidant capacity (T-AOC) significantly increased and then decreased with increasing dietary lipid levels (P0.05). The maximum of serum catalase (CAT) activity was found in the 10.81% lipid group, which are significantly higher than other groups (P0.05). There were no significant difference in hepatic CAT activity and malondialdehyde (MDA) content among dietary treatments (P0.05). These results suggest that proper dietary lipid level can improve the health of Furong crucian carp, but excess dietary lipid may exert adverse effects. Based on the second-order regression analysis of WGR, the optimal dietary lipid level in juvenile furong crucian carp was 6.94%.