Abstract The hypothesis that xylanase and a stimbiotic improve apparent ileal digestibility (AID), apparent cecal digestibility (ACD), and apparent total tract digestibility (ATTD) of energy, insoluble dietary fiber (IDF), soluble dietary fiber (SDF), and total dietary fiber (TDF) in diets containing wheat middlings fed to growing pigs was tested. Twenty-four barrows (initial body weight: 48.39 ± 7.30 kg) with a T-cannula in the distal ileum and another T-cannula in the proximal colon were allotted to a randomized complete block design with 8 pigs per diet. The control diet was based on corn, soybean meal, and wheat middlings, and two additional diets were formulated by supplementing the control diet with 100 g/ton of xylanase or 100 g/ton of stimbiotic. The exogenous xylanase (Econase XT 25) and the stimbiotic (Signis) were supplied by AB Vista, Marlborough, UK. Pigs were housed individually in crates and fed experimental diets for 35 days. A blood sample was collected on d 27 and plasma was analyzed for peptide YY. Fecal samples from pigs fed experimental diets were collected on d 28 to d 31, colon digesta samples were collected on d 32 and 33, and ileal digesta samples were collected on d 34 and 35. The ex-situ pH of colon or ileal digesta was measured on days 32-33, and days 34-35, respectively. Data were analyzed using the MIXED procedure of SAS. Diet was the fixed effect, and block and replicate within block were random effects. Results indicated that the AID of dry matter, energy, IDF, and TDF were greater (P 0.05) in diets containing xylanase or stimbiotic compared with the control diet (Table 1), indicating that xylanase and stimbiotic enhance hydrolysis of fiber and fermentation in the small intestine. Xylanase also tended to increase (P 0.10) the AID and ACD of SDF compared with the control diet. However, only the diet containing xylanase had greater (P 0.05) ACD and ATTD of dry matter, energy, IDF, and TDF compared with the control diet, likely because the xylo-oligosaccharides in the stimbiotic were already fermented in the ileum, and therefore, did not impact the cecum and colon digestibility. The ex-situ pH of colon and ileal digesta, and the peptide YY concentrations in the plasma of pigs were not impacted by xylanase or stimbiotic addition to the diet. In conclusion, addition of xylanase increased the AID, ACD, and ATTD of dry matter, energy, IDF, and TDF in diets for pigs containing wheat middlings, and stimbiotic increased AID of dry matter, energy, IDF, and TDF.
Acosta et al. (2026) studied this question.