Abstract
The objective of this experiment was to evaluate the effects of a Bacillus subtilis xylanase on nutrient digestibility, intestinal health, and growth performance of broiler chickens undergoing an intestinal challenge. Nine hundred one-day-old Cobb 500 male chicks were randomly distributed into three dietary treatments with 10 replicates (30 birds/pen) until 42 d. Treatments were: Control (CT) diet, energy reduction (ER) diet, and the ER diet supplemented with B. subtilis endo 1,4-β-xylanase at 100 g/t (ER+xylanase). The ER diets had metabolizable energy reductions as per manufacturer guidelines: 80, 82, 87, and 92 kcal/kg for pre-starter, starter, grower, and finisher, respectively. All birds were challenged with Eimeria spp. on d 1 and Clostridium perfringens on d 12-14. Feed intake, body weight gain (BWG), and feed conversion ratio (FCR) were evaluated weekly. On d 17, the intestinal permeability was determined using fluorescein isothiocyanate-dextran (FITC-d) as marker. On d 21, I See Inside (ISI) methodology assessed intestinal alterations. On days 21 and 42, nutrient digestibility and cecal short-chain fatty acids (SCFA) concentrations were calculated. Data underwent ANOVA or Kruskal-Wallis tests, followed by Fisher or Dunn tests, respectively. From 0 to 42 d, broilers fed the ER+xylanase diet had greater (P = 0.046) BWG than birds fed the ER diet, while FCR showed improvements in CT and ER+xylanase diets. Broilers fed the ER+xylanase diet had improved intestinal integrity with the lowest (P = 0.017) serum FITC-d concentration and highest (P = 0.057) Mucin-2. Pancreas ISI scores were worsened (P = 0.034) in CT and ER diets compared to ER+xylanase diet. Ileal digestibility of DM and energy, and SCFA were greater (P ≤ 0.006) in broilers fed the ER+xylanase diet compared to ER diet. In conclusion, the B. subtilis xylanase supplementation improved nutrient digestibility, enhanced intestinal barrier integrity and increased SCFA concentrations which improved growth performance in broilers undergoing an intestinal challenge. Results indicated that this xylanase was able to compensate the energy reduction in corn-soy diets fed to broiler chickens.