Evaluation of feeds with different NSP levels on digestive enzyme activity, intestinal histology, and digestibility of Nile tilapia Oreochromis niloticus

Abstract

The increasing use of plant-based feed ingredients may lead to an increase in the level of non-starch polysaccharides (NSP) in fish feed. This study was conducted to assess the effects of varying dietary NSP levels on digestive enzyme activity, intestinal histology, postprandial blood glucose levels, and feed digestibility in Nile tilapia (Oreochromis niloticus). The present study consisted of three treatments, namely control–diet (Low–NSP, 11.59%), Medium–NSP (22.51%), and High–NSP (31.76%) with five replications for each treatment. Nile tilapia with an initial weight of 17.04 ± 0.11 g were kept in aquariums at a density of 15 fish for 30 days. The results showed that the low NSP feed resulted in higher protease, lipase, and amylase enzyme activity compared to the other treatments. The low NSP treatment had greater villi height and wider surface area in the midgut area of the intestine, whereas the high NSP treatment showed higher villi height and surface area in the hindgut area. Protein, fat, dry matter, energy, and phosphorus digestibility were significantly higher in the low NSP (P<0.05). Fish in the low NSP treatment showed higher postprandial blood glucose levels compared to the other treatments. Furthermore, growth performance and retention of protein, lipid, and phosphorus were higher in fish maintained in the low NSP treatment (P<0.05) compared to other treatments. In conclusion, the present study demonstrated that different dietary levels of NSP resulted in different levels of digestive enzyme activities, changes in intestinal structure, feed digestibility as well as growth and nutrient retention in Nile tilapia.

Keywords: enzyme activity, feed digestibility, Nile tilapia, non-starch polysaccharides (NSP)