| The experiment was conducted to study the effects of Bacillus subtilis JS01 on digestion function, intestinal microflora and immune function of common carp (Cyprinus carpio) infected by Aeromonas hydrophila XS91-4-1. In trial,840 common carps with initial body weight 10g±0.2g were randomly dividied to 7 groups with 3 replicates,groups 2-7 were I/P injected with A. hydrophila and group 1 was injected with normal saline. Group 1 and 2 were fed with the basal diet, group 3-7 were fed with the basal diet with B. subtilis at the level of 05,0.25,0.50,0.75,1.00‰. Test for 42 days and the results showed as follows:1. Growth performance:Dietary supplimation with B. subtilis could improve WGR, AGR, SGR and muscle crude protein'significantly (P<0.05). The regression-analysis results indicated that there were quadratic regression relationship between the level of added B. subtilis and WGR (R2=0.8722, P<0.05), muscle crude protein (R2=0.8634, P<0.05). The significant correlation existed between muscle crude protein and WGR (r1=+0.984, P<0.01). These data suggested that B. subtilis could improve growth performance that was correlated with the improvement of crude protein content in muscle.2. Digestive ability:Dietary supplimation with B. subtilis could improve intestine length, intestine length index, height of intestinal folds, hepatosomatic index, hepatopancreas protein content, intestinal protein content, amylase activity, lipase activity, trypsin activity, chymotrypsin activity in intestine significantly (P<0.05). The regression-analysis results indicated that there were quadratic regression relationship between the level of added B. subtilis and intestine length (R2=0.9018, P<0.05), intestine length index (R2=0.9089, P<0.05), height of intestinal folds (R2=0.8842, P<0.05), hepatopancreas protein content (R2=0.9132, P<0.05), intestinal protein content (R2=0.8933, P<0.05), lipase activity (R2=0.9165, P<0.05), trysin activity (R2=0.9545, P<0.05), chymotrypsin activity (R2=0.8894, P<0.05). The significant correlation existed between WGR and intestine length, intestine length index, height of intestinal folds (r1=+0.964, P<0.01; r2=+0.940, P<0.01; r3=+0.864, P<0.05); The significant correlation existed between muscle crude protein and hepatopancreas protein content,intestinal protein content (r1=+0.951, P<0.01:r2=+0.993, P<0.01); The significant correlation existed between hepatopancreas protein content and lipase activity, trypsin activity, chymotrypsin activity in intestine (r1=+0.914, P<0.05; r2=+0.950, P<0.01; r3=+0.975, P<0.01). These data suggested that B. subtilis could promote the growth of intestine and acitivities of digestive enzymes.3. Intestinal microflora:Dietary supplimation with B. subtilis could improve the number of Bacillus and Lactic acid bacteria in intestine significantly (P<0.05) and reduced the number of A. hydrophila and E. coli in intestine significantly (P<0.05). The regression-analysis results indicated that there were quadratic regression relationship between the level of added B. subtilis and the number of Bacillus (R2= 0.9805, P<0.01), the number of E. coli (R2=0.7943, P<0.05). The significant correlation existed between the number of Bacillus and Lactic acid bacteria, E. coli in intestine (r1=+0.820,P<0.05; r1=-0.900, P<0.05); The significant correlation existed between the number of Bacillus and trypsin activity,chymotrypsin activity, hepatopancreas protein content,intestinal protein conten (r1=+0.966, P<0.01; r2= +0.965, P<0.01; r3=+0.967, P<0.01; r4=+0.966, P<0.01). These data suggested that B. subtilis could improve the growth of beneficial bacteria and reduce the growth of hamfull bacteria, as well as the growth of beneficial bacteria was correlated with the improvement of digestive ability.4. Immune function:Dietary supplimation with B. subtilis could improve splenic index, lysozyme activity, the concentration of C3 and C4 significantly (P<0.05). The regression-analysis results indicated that there were quadratic regression relationship between the level of added B. subtilis and splenic index, lysozyme activity, the concentration of C3 and C4 (R21=0.9427, P<0.05; R22=0.8935, P<0.05; R23=0.9453, P<0.05; R24=0.8654, P<0.05). The significant correlation existed between splenic index and lysozyme activity, addiment C3, addiment C4(r1=+0.905, P<0.05; r2=+0.821, P<0.05; r3=+0.958, P<0.01). These data suggested that B. subtilis could improve immune function by promoting the growth of immune organs and the level of immue-related indicators.5. The optimum amount of B.subtilis:In a diet for common carp infected by Aeromoas hydrophila appeared the best growth performance, digestive function, the growth of helpful microflora, ingestive function as feeding the diets containing B. subtilis at the level of 0.63‰,0.57‰-0.66‰,0.53‰-0.58‰and 0.51‰-0.66‰respectively. |
PDF Full Text Request