Effects Of Dietary Biotin On Digestive Ability, Antioxidative Ability And Immune Function Of Juvenile Jian Carp (Cyprinus Carpio Var.Jian)

A total of 1400 juvenile Jian carp (Cyprinus carpio var. Jian) (7.72±0.02 g) were fed diets containing graded levels of biotin (0.01,0.028,0.054,0.151,0.33,1.54,2.68 mg kg-1 diet) for 63 days to investigate the effects of biotin on digestive and absorptive abilities, immune function and antioxidative ability. After 63-day feeding trial, thirty fish with similar weight was randomly slected from each treatment to conduct a challenge trial with Aeromonas hydrophila for 17 days.Deficiency syndromes such as anorexia, poor growth and dark skin colour were observed in juvenile Jian carp fed on biotin-deficient diet (unsupplemented control group) for 6 weeks (plus the acclimation period of 4 weeks). Biotin levels great significantly improved PWG, FE, FI, PRV, PPV, LPV, GPT activities in muscle and hepatopancreas, GOT activities in hepatopancreas, HSW,ISW, IL, IPC, folds height in PI, MI and DI, trypsin, amylase, lipase, chymotrypsin activities in hepatopancreas and intestine, CK,γ-GT, AKP and Na+, K+-ATPase activities in intestine (P<0.01). FI was positively correlated with trypsin, chymotrypsin, lipase and amylase activities in hepatopancreas (r1=+0.942, r2=+0.920, r3=+0.965, r4=+0.913, P<0.01). FE was positively correlated with AKP, y-GT, CK activities in PI, MI and DI (r1=+0.961, r2=+0.926, r3=+0.966, r4=+0.964, r5=+0.977, r6=+0.941, r7=+0.943, r8=+0.950, r9=+0.968, P<0.01). The trens of MDA, PC in serum, muscle, hepatopancreas, head kidney, hind kidney and spleen was opppsite with SGR. Patterns of differences in GSH content, GR, GST, SOD, GPX, CAT, ASA and AHR activities in serum, muscle, hepatopancreas, head kidney, hind kidney and spleen were similar with that in SGR.. Intestinal Aeromonas and Escherichia coli decreased with increasing dietary biotin, whereas the trends of Lactobacillus and Bacillus were opposite (P<0.01). Biotin great significantly affected head kidney weight, spleen weight, leukocyte phagocytic activity, red and white blood cell count, lysozyme, acid phosphatase activity, lectin levels, addiment C3 and C4, IgM (P<0.01). In conclusion, biotin promoted growth rate, FI, FE, PPV and LPV of juvenile Jian carp. Biotin increased the growth and development of pancreas and intestine, enhanced trypsin, chymotrypsin, lipase and amylase secretions of pancreas, and folds height and absorptive enzymes activities of intestine, influenced the balance of intestinal microflora in juvenile Jian carp. Biotin depressed the peroxidation of lipid and protein, and removed superoxide radicals and hydroxyl radical in intestine, hepatopancreas, muscle, head kidney and spleen. Meanwhile, biotin increased antioxidant enzymes activities and GSH content in intestine, hepatopancreas, muscle, head kidney and spleen of juvenile Jian carp. Biotin could improve disease resistance of juvenile Jian carp by enhanced phagocytosis and bacteriolysis of the leukocytes and specific antibody production. The dietary biotin requirement for Jian carp (7.72-32.67 g) estimated by the broken-line analysis based on SGR was 0.15 mg kg-1 diet.