Effect of Bromelain-Fermented Diets on Digestive Enzyme Activities and Muscle Proximate Composition of Labeo Rohita

Abstract

Plant proteins are considered most suitable to replace fish meal because they are cheap, readily available, and abundant. However, plant proteins are not digested efficiently in fish due to the presence of complex protein structures. Therefore, this preliminary study was conducted to evaluate the effect of bromelain-fermented plant diets on the digestive enzyme activities and muscle proximate composition of Labeo rohita. For this purpose, healthy fingerlings with an average initial weight of 10±0.2 g were procured and acclimatized under laboratory conditions. Then, 20 fingerlings were transferred to each of 20 glass aquaria (160 L capacity) in three replicates. Five diets were prepared using plant meals and were fermented using 10, 20, 30 and 40% bromelain powder for 48 hours at 55°C. The control diet was not fermented. Fermented diets were fed to fish for 90 days, and then digestive enzyme activities and muscle proximatecomposition were determined. Fish fed bromelain-fermented diets (10-40%) showed a significant increase in digestive enzyme activities (protease and lipase) compared with the control group. However, no significant effect was observed on the amylase activities in fish fed bromelain-fermented diets. Muscle proximate composition revealed that crude protein (CP) contents were increased while crude fat (CF) contents were decreased in fish fed fermented diets compared with the control group. However, no significant differences were observed in moisture and ash contents. In conclusion, fish fed fermented diets showed enhanced activities of digestive enzymes (protease and lipase) and crude protein contents in the muscle of L. rohita. Therefore, it is recommended to conduct a detailed trial on bromelain fermentation.