Carbohydrases supplementation increased nutrient utilization in white seabream (Diplodus sargus) juveniles fed high soybean meal diets

• White seabream accept, grow and utilize diets with low or very low FM inclusion level.
• Dietary carbohydrases supplementation considerably increased overall feed utilization, reducing wastes.
• Carbohydrases supplement may have a great economic and environmental impact in omnivorous aquaculture fish production.

A study was undertaken to evaluate the effects of supplementation of high soybean meal (SBM)/low fish meal (FM) based diets for white seabream (Diplodus sargus) juveniles with Natugrain® TS, a nonstarch carbohydrases (NSPase) enzyme complex. Four isoproteic (36% CP) and isolipidic (18% CL) diets were formulated in a 2 × 2 factorial design with FM/SBM levels and NSPase supplementation as factors. Diets included 15%FM/32%SBM or 5%FM/42%SBM, supplemented or not with 0.04% of Natugrain® TS. Twelve groups of 15 fish (IBW = 58 g) were fed each diet to near satiation for 10 weeks. The apparent digestibility coefficients of the diets were evaluated in a different trial. Reduction of dietary FM from 15 to 5% did not affect voluntary feed intake, growth performance, feed efficiency, whole body composition, apparent digestibility coefficients, distal intestine and liver histomorphology, and digestive enzyme activities. However, dietary NSPase supplementation greatly increased overall feed, protein, and energy utilization, and this effect was higher in the low than in the high FM diet. Whole-body protein and lipid content also increased with dietary NSPase supplementation, and nitrogen and energy fecal losses were reduced. Moreover, in the low FM diet NSPase supplementation promoted an increase of amylase and lipase activities but not of protease activity. Overall, results indicate that white seabream perform well with diets almost devoid of FM. Also, NSPase supplementation to high plant feedstuff diets improves feed and nutrient utilization efficiency, and contribute to a reduction of fecal waste production.Statement of relevanceDietary supplementation with carbohydrase complexes is a possible strategy to overcome some of the drawbacks of plant based feedstuffs diets for aquaculture species, enhancing nutrient availability and alleviate digestive disorder. White seabream accepted, grew and utilized almost non-FM diets, if dully supplemented with carbohydrases. Dietary carbohydrase supplementation considerably increased feed utilization efficiency, reducing environmental waste.