Comparing the efficacy of stimbiotic and a combination of xylanase and beta-glucanase, in broilers fed wheat-barley based diets with high or low AME

A stimbiotic is defined as a product that stimulates a fibre-degrading microbiome to increase fibre fermentability. The aim of this study was to examine if it is more advantageous to feed a stimbiotic (xylanase + xylo-oligosaccharides (STB)) or a combination of xylanase and beta-glucanase (Xyl + BG) to broilers fed wheat-barley based diets with differing AME levels. Cobb 500 broilers (n = 480, 80 birds per treatment) were fed 6 dietary treatments in a 2 × 3 factorial arrangement; two AME levels, 'High' or 'Low', which differed by 100kcal ME/kg, and three additive supplementations, with no supplemental additives, STB or Xyl + BG. Diets were fed as three phases, starter (d 0–14), grower (d 14–21) and finisher (d 21–35). On bird age d14, 21 and 35, total pen body weight and feed intake were determined, and feed conversion ratio corrected for mortality (cFCR) was calculated. On d21 and d35 ileal viscosity and beta-glucan content and caecal SCFA concentration were determined. Additive suplementation had no impact on cFCR in birds fed the low AME diet, but in birds fed the high AME diet the cFCR value was reduced in the presence of the additives (P = 0.001 and P = 0.015, at d14-21 and d21-35, respectively). At d21, caecal SCFA concentration was consistently higher (P = 0.015), and ileal beta-glucan level lower (P = 0.002), in birds fed the diet supplemented with STB compared to those without additives. At d35, ileal viscosity was lower in birds fed STB compared to those fed the diet without supplementation of additives, irrespective of diet AME level (P = 0.017). These results suggest that both STB and Xyl + BG ameliorate the antinutritive effects of the non-starch polysaccharides (NSP) present in wheat-barley based diets, resulting in improved bird performance. However, supplementation with STB induces a comparatively greater positive effect on NSP hydrolysis and SCFA production.