Effects of Different Microbial Preparations on the Growth, Physical Indices and Intestinal Tissue Structure of Micropterus salmoides

In order to explore the effects of different microbial preparations on the growth, body index and intestinal tissue structure of Micropterus salmoides, different concentrations of Clostridium butyricum 0 (group A, CK), 0.25% (group B), 0.5% (group C), 1% (group D) Clostridium butyricum (5×10⁸ cfu·g^-1), 0.2% yeast products (group E) and their mixture (0.25% Clostridium butyricum+0.2% yeast products, group F) were added to the commercial compound feed for a two-stage breeding experiment for 17 weeks. The results showed that: in the first stage (14 weeks), except for adding 0.2% yeast products (group E), the growth performance of Micropterus salmoides was significantly improved compared with the control group, and the effect of adding 0.5% Clostridium butyricum was the best. In the second stage (17 weeks), the final mean weight and final body length of 0.5% Clostridium butyricum (group C) and 0.25% Clostridium butyricum+0.2% yeast products (group F) were significantly higher than those of the control group A. There were no significant differences in the fullness, visceral-body ratio index, length of intestinal villus and muscle layer thickness among the three groups. However, compared with the control group (group A), the indexes of adding 0.5% Clostridium butyricum (group C) had an increasing tendency, and the indexes of adding 0.25% Clostridium butyricum+0.2% yeast products (group F) had a decreasing tendency. The results showed that under the experimental conditions, the addition of 0.5% Clostridium butyricum to the commercial compound feed had the best effect on the growth and improvement of intestinal health of Micropterus salmoides.