Effect of NSPase and feeding regimen on performance, nutrient digestibility and ileal microbiota of broiler chickens fed pelleted diets containing low- or high-viscosity barley

The effects of NSPase, barley variety and feeding regimen and their interactions on the performance, nutrient digestibility, digestive tract characteristics and ileal microbiota were studied. A total of 1936 eleven-day-old Ross 308 female broilers were given ad libitum (ADL) or intermittent (INT) access to pelleted diets based on low-viscosity (LVB) or high-viscosity (HVB) barley at 540 g/kg, with or without a cocktail of β-glucanase and xylanase (Ronozyme® MultiGrain) at 0.1 g/kg in a replicated pen trial. From d 11 to 17, INT birds had interrupted feed access for 8 h daily, which reduced to 7 h daily from d 18 to 33, while ADL birds had continuous feed access for 18 h daily. Supplementation with NSPase improved weight gain and FCR, reduced water intake and load of ileal C. perfringens and the effect was larger with HVB diets due to interactions between NSPase and barley variety ( p < 0.025). Despite higher weight gain and feed intake with ADL feeding ( p < 0.001), FCR and ileal bacterial load was lower with INT feeding ( p < 0.001). Protein digestibility was improved with NSPase supplementation and with INT feeding ( p < 0.009). The HVB diets resulted in higher jejunal digesta viscosity, longer small intestines and more sticky/watery excreta ( p < 0.001), all of which were offset with NSPase supplementation ( p < 0.025). Overall, the HVB diets performed more poorly regardless of their better response to NSPase, than the LVB diets. Furthermore, the effect of NSPase and INT feeding on nutrient utilization, FCR and gut health was additive.