Xylanase and β-glucanase in tandem improve performance, digestive enzymes activity and digestibility in juvenile Nile tilapia fed corn distillers’ dried grains with solubles-added diet

Recently studies have demonstrated the benefits of xylanase and β-glucanase (XB) in enhancing the digestibility of nutrients in Nile tilapia (Oreochromis niloticus) fed fiber-rich diets. However, the underlying mechanisms of XB on digestive enzymes activity and growth performance are not fully understood. Therefore, this study aimed to determine the effect of XB supplementation on growth performance, blood parameters, activity of digestive enzymes, and apparent digestibility coefficients (ADC) in juvenile Nile tilapia fed corn distillers' dried grains with solubles (DDGS)-contained diets. A 2 × 2 factorial design was used with two DDGS supplementation levels: one without DDGS (control) and one with 185 g/kg corn DDGS, either unsupplemented (−XB) or supplemented with 0.2 g/kg diet of XB (+XB). Each diet was tested using four replicates of 12 fish each. The fish (n = 192; 7.49 ± 0.07 g) were hand-fed six times daily until apparent satiety over eight weeks. DDGS inclusion improved body weight gain, energy retention efficiency, ADC of crude lipids, and digestive amylase and lipase activity. Fish fed control and DDGS diets with XB had higher feed efficiency ratio (+12.7%), energy retention efficiency (+12.5%), whole-body crude lipids (+6.5%), plasmatic cholesterol (+5.7%), activity of and lipase enzyme (+18.0%), and ADC of crude lipids (+8.8%) than those fed XB-unsupplemented diets. Exogenous XB in DDGS-contained diets increased digestible energy (DE) content by 2.22 MJ/kg, relative to values found in diet with DDGS without XB supplementation. XB improved digestible protein (DP) content by 2.9 g/kg diet relative to value found in the corresponding diets without XB supplementation. Overall, XB supplementation effectively alleviates the adverse effects of NSP in corn DDGS, enhancing digestive enzyme activity, and digestibility of energy and nutrients, thereby improving growth performance of juvenile Nile tilapia. The findings highlight the potential of corn DDGS as a sustainable and nutritive feedstuff for tilapia production.