|
|
|
| Effects of Dietary Bacterium Bacillus thuringiensis on Immune Response of Common Carp |
| YIN Hai-cheng,ZHAO Hong-yue |
|
|
|
|
Abstract The common carp Cyprinus carpio immunized with Aacillus hydrophila (groups A_0～A_3) and un-immunized (groups B_0～B_3) were fed the diets containing bacterium Bacillus thuringiensis at a rate of 1.0×10~(11), 3.0×10~(11), and 5.0×10~(11)cfu/kg to investigate the effect of the bacterium on the immune response of the common carp in Yellow River. The phagocytic activities of leucocytes, lysozyme activities, and agglutinating antibody titer were determined 0, 15, 30, and 40 days after the feeding trial. The results showed that the fish fed the diets containing different levels of Bacillus thuringiensis had significantly enhanced phagocytic activities of leukocytes, and lysozyme activities(P < 0.05), increasing with the increment in the levels of the bacterium. There were no significant differences in phagocytic activities of leukocytes for the immunized and un-immunized fish (P>0.05), but significant differences in the lysozyme activities(P<0.05). The significant differences in the phagocytic activities of leucocytes and lysozyme activities were not observed 10 days after the fish stopped feeding the diets(P>0.05). The different concentrations of Bacillus thuringiensis improved the agglutinating antibody titer and the survival of the fish after the fish challenged with live Aeromonas hydrophila. The immunized fish had the maximal relative percent survival (RPS) when fed the diets containing the Bacillus thuringiensis at a rate of 5.0×10~(11)cfu/kg feed.
|
|
Received: 25 November 2009
|
|
|
|
|
|
|
