A dose–response study to evaluate the effects of pH-stable β-mannanase derived from Trichoderma citrinoviride on growth performance, nutrient retention, and intestine morphology in broiler chickens

The objective of this trial was to determine the optimal supplementation level of β-mannanase preparation enzyme from Trichoderma citrinoviride on growth performance, apparent total tract retention of nutrients and gut health of broiler chickens. A total of 600 broiler chickens (Ross 308) were randomly allotted to four treatments on the basis of similar body weight. The dietary treatments included a corn soybean-based diet supplemented with 0 (control), 1200, 2400, or 4800 MNU/kg β-mannanase preparation. The experimental diets were fed in crumbles in phase 1 (1 to 14 days) and pellets in phase 2 (15 to 35 days). The linear and quadratic contrasts were used to compare effects of increasing dietary β-mannanase preparation levels. The overall result indicated a linear increase (p < .01) in overall body weight gain and feed conversion ratio. The retention of N, GE, soluble none starch polysaccharide, and insoluble none starch polysaccharide linearly improved in the phase 1 and phase 2 (p < .05). A linear response to increasing dietary β-mannanase was demonstrated for the digesta viscosity (p < .01). Increasing β-mannanase level in the diets increased the concentration of mannose, galactose, and glucose in ileum and caecum. An increase in villus height of the jejunum with increasing dietary levels of β-mannanase was observed (linear, p < .05). In addition, villus height of the duodenum and the ileum tended to increase (linear; p = .06) and with increase in dietary β-mannanase. In conclusion, this β-mannanase has potential to improve the growth performance, apparent total tract retention of nutrients and gut health of broiler chickens fed a corn SBM-based diet.Highlights Dietary β-mannanase improved the growth performance of broiler chicks by increasing the retention of gross energy, soluble NSP and insoluble NSP. The viscosity of digesta in ileum was linearly increased as dietaryβ-mannanaselevel increased. An increase in villus height of the jejunum was observed with increasing dietary levels ofβ-mannanase.