Effect of supplementation of non-starch polysaccharide-degrading enzymes on nutrient digestibility of wheat and wheat millrun based diets in growing pigs

Abstract Text: Nutrient digestibility of wheat millrun (WMR) is limited by non-starch polysaccharides (NSP) such as arabinoxylans. Supplementation of NSP-degrading enzymes may increase nutrient digestibility of WMR. Effects of supplementation of 2 endo-xylanases, fed with or without 2 arabinofuranosidases, on nutrient digestibility of a wheat and WMR-based diet were evaluated in a 6 × 6 Latin square. Six ileal-cannulated barrows were fed 5 test diets and one N-free diet in six 9-d periods. Five test diets contained 56.2% wheat, 40% WMR, and added enzymes as follows: 1) control (diet C), without enzyme; 2) 10 mg enzyme protein (EP)/kg of xylanase Ronozyme WX (diet X1); 3) 10 mg EP/kg of xylanase GH11 (diet X2); 4) 10 mg EP/kg of xylanase Ronozyme WX + 5 mg EP/kg of arabinofuranosidase GH43 + 5 mg EP/kg of arabinofuranosidase GH51 (diet X1A); and 5) 10 mg EP/kg of xylanase GH11 + 5 mg EP/kg of arabinofuranosidase GH43 + 5 mg EP/kg of arabinofuranosidase GH51 (diet X2A). Feces and ileal digesta were collected sequentially for 2 d. Data were analyzed using MIXED procedure of SAS. Wheat and WMR contained 12.2% and 21.2% total NSP, respectively. Insoluble NSP were greater than soluble NSP, respectively, in wheat (10.8 vs. 1.4%), WMR (18.8 vs. 2.4%), and diets (14.6 vs. 5.1%). Digesta viscosity (resistance to flow) was greatest for diet C. Compared with C (377 Pascal-second (Pa.s)) digesta viscosity was reduced by 15.1% (P < 0.05) for diet X2A (320 Pa.s), while viscosity was not affected for diets X1 (362 Pa.s), X2 (354 Pa.s), and X1A (348 Pa.s). Apparent total tract digestibility (ATTD) of GE and CP were greater (P < 0.05) for diets X2 and X2A than for diet C. Specifically, ATTD of GE was 79.7, 80.3, 81.0, 80.3, and 81.3% and ATTD of CP was 81.9, 82.1, 83.3, 83.1, and 83.7%, respectively, for diets C, X1, X2, X1A, and X2A. Diets X1A and X2A increased (P < 0.05) apparent ileal digestibility (AID) of NSP compared to diets C, X1, and X2. Compared with control, diets X1A and X2A increased (P < 0.05) AID of insoluble and total NSP, insoluble and total arabinose, insoluble and total xylose by 52, 42, 86, 80, 85, and 84%, respectively. In conclusion, combined application of xylanase and arabinofuranosidase was more effective than single application of xylanase to increase the nutritional value of diets based on wheat and WMR.

Keywords: wheat co-product, xylanase, arabinofuranosidases