Evaluation of rice distillers' dried grains soluble (DDGS) blended with non-starch polysaccharidases (NSPase) as a fish meal substitute in the diet of climbing perch, Anabas testudineus juveniles

Abstract

A study was undertaken to evaluate the effects of supplementation of rice distiller’s dried grains Soluble (DDGS) in the diet for climbing perch, Anabas testudineus juveniles with non-starch polysaccharidases (NSPase) (Cellulase:Xylanase: Arabinoxylanase: Glucanase::1:1:1:1 w/w) enzyme complex. Twelve isoproteic (40 % crude protein) and isolipidic (8 %) semi-purified diets were formulated in a 4 × 3 factorial design with fishmeal (FM)/rice DDGS levels and NSPase supplementation as factors. Diets included four levels of rice DDGS viz.0, 10, 20, or 30 % replacing up to total dietary fish meal (FM), supplemented with three levels (0, 0.1 or 0.2 %) of NSPase. Thirty six groups of 15 fish (average weight, 5.00 ± 0.2 g) were fed each diet to near satiation for 60 days. Increase of dietary rice DDGS inclusion up to 20 % significantly increased (p < 0.05) the growth performance, feed efficiency, and digestive enzyme activities in juveniles compared to the 0 % & 10 % inclusion levels of rice DDGS, however, these parameters significantly decreased in the treatment fed with diet having 30 % inclusion level of rice DDGS in place of FM. Fish fed diets with either 10 % or 20 % rice DDGS recorded significantly (P < 0.05) higher activities of protein metabolism enzymes (AST and ALT). Likewise, an increase in rice DDGS inclusion up to 20 % significantly (P < 0.05) increased glycolytic enzyme activities (Hexokinase and Pyruvate kinase) in juvenile A. testudineus, recording the lowest in the control group. However, dietary NSPase supplementation increases growth, nutrient utilization as well as improved digestive and metabolic enzyme activities compared to non-supplemented group. As a consequence, supplementation of NSPase at 0.2 % could further enhance the inclusion level of rice DDGS up to 30 % and encourage total replacement of fish meal in the diet of climbing perch (Anabas testudineus) juveniles without compromising the growth and nutrient utilization. Overall, results of this study indicate that total replacement of FM by rice DDGS in the diets for climbing perch reduced the growth and feed utilization, while supplementation of rice DDGS-based diet with 0.2 % exogenous NSPase improved growth performance and feed utilization efficiency, and ultimately shall reduce the final cost of the feed from commercial point of view.