Effect of probiotics for common carp (Cyprinus carpio) based on growth performance and digestive enzyme activities

Effect of probiotics for common carp (Cyprinus carpio) based on growth performance, feed utilization (feed conversion ratio, FCR) and digestive enzyme (protease, amylase and lipase) activities was investigated. The photosynthetic bacteria and Bacillus sp. isolated from common carp ponds were added to carp basal diets as the probiotics in three forms: 1 g kg−1 lyophilized photosynthetic bacteria cells (PSB), 1 g kg−1 lyophilized Bacillus sp. (B) and their mix. Twelve aquaria with replicates for treatment and control were used. After a 60-day feeding experiment with probiotics supplemented and non-supplemented control diets, the diets supplemented with probiotics showed significantly better results of growth performance and FCR than those with the basal diet (control). Mean digestive enzyme activities of all probiotics treatment groups were significantly different (P<0.05) with that of the control. The protease activity was remarkably higher in the mix and Bacillus sp. compared with PSB and control. However, there was no difference between the mix and Bacillus sp. As for amylase and lipase, assays showed higher activity in the mix as compared to the rest. In conclusion, it showed that probiotics highly increased the growth performances and digestive enzyme activities, and decreased FCR. Furthermore, different probiotics forms indicated different performances and the mix produced the best results.