Cellulase activity in rohu fingerlings

The activity of cellulase was determined in the intestine of rohu, Labeo ro hita, fingerlings fed on separate dietary formulations incorporating Leucae na leaf meal and synthetic cellulose at 20% level in proportional replaceme nt of the ingredients from the fish-meal-based reference diet. Three more r eplicate experimental diets were prepared by incorporating 1% tetracycline, a broad-spectrum antibiotic, into the former three dietary formulations so as to circumvent the action of microflora in digestive function. Cellulase activity was found to be highest in fish fed on the cellulose incorporated diet, followed by those maintained on the plant-protein-based and referenc e diets, respectively. A diet-dependent variation in cellulase activity was apparent. However, a sharp decline in the level of cellulase activity was observed in the fish fed diets containing tetracycline, which is supposed t o have destroyed all the gut microflora. The microbial culture of intestina l and hepatopancreatic extracts also confirmed the absence of microflora in the fish fed tetracycline-compounded diets. The study indicates that cellu lase activity in rohu is largely contributed by the intestinal microflora, while the reduced activity recorded in the fish reared on antibiotic-compou nded diets may be due to the presence of some other source of cellulase sec retion apart from cellulolytic microbial action. The information generated from the present investigation might contribute towards better feed formula tion for carp at low cost, incorporating plant-based feed ingredients.