Effect Of Lactobacillus Fermentum In The Diet On Growth Performance, Functions Of Digestion, Absorption And Immune Of Juvenile Jian Carp (Cyprinus Carpio Var.Jian)

The experiment was to investigate the effect of dietary Lactobacillus fermentum supplement on growth performance, functions of digestion, absorption and immune. In 80 days feeding trial, a total of 720 juvenile Jian carp(Cyprinus carpio var. Jian) (22.35±0.06g. mean±SD) were randomly distributed into six groups of each three replicates, feeding diets containing graded levels of Lactobacillus fermentum(1×10′cfu/g diet):0.00%,0.05%,0.10%,0.15%,0.20%,0.25%. After the growth trial,30 fish in each treatment were randomly assigned to a challenge trial conducted by injection of Aeromonas hydrophila for 17 days.Results indicated that Lactobacillus fermentum great significantly improved specific growth rate (SGR) (P<0.01), feed intake (FI) (P<0.01), protein efficiency ratio (PER) (P<0.01), protein production value (PPV) (P<0.01), lipid production value (LPV) (P<0.01), ash production value (APV) (P<0.01), hepatopancreas weight (P<0.01), hepatopancreas index (HSI) (P<0.01), hepatopancreas protein content (HPC) (P<0.01), intestine weight (P<0.01), intestine length index(ILI) (P<0.01), intestine protein content (IPC) (P<0.01), intestinal folds height (P<0.01), the activity of tryspin in hapatopancreas (P<0.01), the activity of lipase (P<0.01), amylase (P<0.01), chymotrypsin (P<0.01) in hapatopancreas and intestine brush border enzymes containing alkaline phosphatase (AKP) (P<0.01), Na+,K+-ATPase (P<0.01), gamma-glutamyl transpeptidase (γ-GT) (P<0.01) and creatine kinase (CK) (P<0.01). Meanwhile, Lactobacillus fermentum also significantly improved feed efficiency rate (FER) (P<0.05),intestine length (IL) (P<0.05) and the acticity of tryspin in intestine (P<0.05). Correlation analysis showed SGR and FER were all positive related to the development of hepatopancreas and intestine and digestive enzyme activities. There were great significantly or significantly correlation between FER and chymotrypsin, trypsin, lipase, amylase of intestine (r1=+0.984, P<0.01; r2 =+0.835, P<0.05; r3=+0.947, P<0.01; r4=+0.904, P<0.05), and there were great significantly or significantly correlation between FER and AKP, y-GT in proximal intestine (PI), mid intestine (MI) and distal intestine (DIS) in whole intestine (r1=+0.982, P<0.01; r2=+0.972, P<0.01; r3=+0.975, P< 0.01; r1=+0.951, P< 0.01; r2=+0.902, P< 0.05; r3=+0.815, P< 0.05).and there were also great significantly or significantly correlation between FER and Na+, K+-ATPase in mid intestine (MI) and distal intestine (DIS) in whole intestine(r,=+0.896, P<0.05; r2=+0.965, P<0.01). Those suggest that dietary Lactobacillus fermentum promote growth of digestive and absorptive organ, enhance the ability of secrete digestive enzymes, improve activities of digestive enzymes and brush border enzymes, and enhance the ability of digestion and absorption of nutrient. Moreover, the counts of erythrocyte (P<0.01) and leucocyte (P<0.01), survival after vaccination (P<0.01), phagocytic activity of leucocytes (P<0.01), sim-immunoglobulin M (sim-IgM) levels (P<0.01), anti-AH antibody titers (P<0.01), the activity of acid phospatase (ACP) (P<0.01), serum lectin titers (P<0.01), total iron-binding capacity (TIBC) (P<0.01), serum complement C3 and C4 levels (P<0.01) and the activity of lysozyme (P<0.01) were directly enhanced by Lactobacillus fermentum supplement. Besides, Lactobacillus fermentum significantly influenced the head kidney, metanephros and spleen weight(P<0.05), and the spleen index(P<0.05). There were significantly correlation between hago-rate of leukocyte and the counts of erythrocyte and leucocyte, total iron-binding capacity (TIBC), sim-immunoglobulin M (sim-IgM) levels (r1=+0.866, P<0.05; r2=+0.873, P<0.05; r3=+0.892, P<0.05; r4=+0.893, P<0.05). Those results indicated that Lactobacillus fermentum promoted immune function.In considering these results, Lactobacillus fermentum promoted development of digestive organs and the ability to secreting trypsin, lipase and amylase, and enhancing the absorbtion function of intestine to improve the ability to digesting and absorbing nutrients to so as to enhance the growth performance of aquatic animals. Meanwhile, Lactobacillus fermentum promoted phagocytosis of leucocyte and bacteriolysis of serum lysozyme and ACP and increased Lactobacillus and Bacillus subtilis in intestine to depresse the reproduction of Escherichia colii and Aeromonas hydrophila in intestine in order to enhance non-specific immune ability of aquatic animals. Lactobacillus fermentum promoted the growth and development of immune organs and enhanced the responses of serum anti-AH so as to enhance specific immune ability and further improve disease of resistance. For 22-110g juvenile Jian carp appeared best growth performance as feeding the diets containing 1.1×10′cfu/g diet. Jian carp appeared best trypsin activity, chymotrypsin and lipase activities in hapatopancreas, ATP and r-GT activities in mid intestine, lysozyme and ACP activities as feeding the diets containing Lactobacillus fermentum level from 1.8×107cfu/g diet to 2.3×107cfu/g diet.