| To study the effect of avilamycin and narasin on the intestinal microflora of Cyprinus carpio, the concentrations of avilamycin of both groups were 4mg/kg and 8mg/kg feed respectively, and the concentrations of narasin of both groups were 20mg/kg and 40mg/kg feed respectively. The quantity and composition of the intestinal bacteria were detected on 0, 14, 28, 42 and 56 d after fed with these antibiotics. The results were as following:1 During the whole experiment, the quantity of the intestinal aerobic and facultative anaerobic bacteria was 6.36-8.49shown in lg value, quantities of the obligate anaerobic bacteria, Bifidobacterium, Lactobacillus and Bacteriodes were 8.87-10.28, 8.45—10.12, 5.55-7.73 and 4.24-5.90 respectively shown in lg value. Before fed with antibiotics, the predominant intestinal aerobic and facultative anaerobic bacteria were Enterobacteriaceae, Flavobacterium, Acinetobacter and Vibrio. Among the anaerobic bacteria, the quantity of Bifidobacterium was the most, Lactobacillus the second, and Bacteriodes the least.2 After Cyprinus carpio was fed with avilamycin, the percent of Vibrio decreased, but the percent of Corynebacterium increased. After avilamycin 4mg/kg was fed to Cyprinus carpio, the quantity and composition of the intestinal aerobic and facultative anaerobic bacteria did not change greatly, except quantity of Lactobacillus decreased significantly on the 14th d, other obligate anaerobic bacteria did not change evidently either. After avilamycin 8mg/kg was fed to Cyprinus carpio, the quantity of the intestinal aerobic and the facultative anaerobic bacteria, the percent of Enterobacteriaceae, and the quantity of Lactobacillus decreased significantly on the 14th d, at the same time , the percent of Flavobacterium increased evidently, the quantity and percent of Bacteriodes decreased evidently during the first 28 d of the experiment.3 After Cyprinus carpio was fed with narasin, the percent of Corynebacterium increased. After narasin 20mg/kg was fed to Cyprinus carpio, The quantity and composition of the intestinal bacteria did not change greatly. After narasin 40mg/kg was fed to Cyprinus carpio, the quantity of the intestinal bacteria decreased evidently on the 14th d, while during whole experiment, the composition of the intestinal microflora did not change greatly. |
