Effect of feed supplementation with effective microorganisms (em) bokashi on hepatopancreas and gut histology, growth performance, and survival rate of freshwater crayfish Pontastacus leptodactylus (Eschscholtz, 1823)

A sixty-day feeding trial was conducted to investigate the effect of dietary effective microorganisms (EM) Bokashi on organ histology, growth performance, and survival rate of freshwater crayfish Pontastacus leptodactylus (Eschscholtz, 1823). Bokashi serum and powder consisted of two major microorganisms as Bacillus amyloliquefaciens spp. plantarum and Lactobacillus plantarum. Four treatment groups were established in control (without bokashi), bokashi powder 1% and 5% supplemented to diets. Bokashi serum was added at a ratio of 0.01% (v/v) of the total volume of the tank water once a week into which there was a constant flow of fresh water at a flow rate of 1.2 L min(-1). The crayfish were fed ad libitum with treatment diets for 60 days. The results showed that there was no significant difference in growth performance among the groups, but survival rates were significantly different between groups (p < 0.05). As a result of the microscopic examination of the intestine, pathological changes such as inflammatory cell infiltrations in the interstitial tissue, and lack of B, F, and R epithelial cells were found in the groups that were supplemented with bokashi while the control group exhibited normal tissue histology. As a result of this study, the addition of nonindustrial bokashi to crayfish diets had no effect on growth. In addition, nonindustrial bokashi products supplementation to crayfish diets caused severe pathological findings in hepatopancreas and guts and a low survival rate.