302 Late-Breaking: Improving the porcine in vitro digestibility of maize using xylanase and cellulase alone or in combination with debranching enzymes.

Abstract A study evaluated the (i) effects of increasing pancreatin dosage level on the porcine in vitro digestibility of dry matter (IVDDM) for corn and wheat, and (ii) porcine IVDDM and solubilization of non-starch polysaccharides (NSP) in corn without or with supplemental enzymes. In Experiment 1, corn and wheat were subjected to a porcine in vitro digestion with varying dosage levels of pancreatin whereas in Experiment 2, corn was subjected to a porcine in vitro digestion with xylanase and cellulase at 4,000 U/kg each without or with low or high doses of arabinofuranosidase (4,000 or 40,000 U/kg) and feruloyl esterase (35 vs. 350 U/kg) individually or in combination with acetyl xylan esterase at 4,000 U/kg. An increase in dosage level of pancreatin product from 200 to 400 mg/g of sample increased (P < 0.05) the IVDDM for corn but not for wheat. A further increase of pancreatin product dosage level from 400 to 600 mg/g of sample unaffected IVDDM. Supplementation of corn with xylanase and cellulase improved (P < 0.05) the IVDDM (86.2 vs. 87.7%), but unaffected the NSP of the undigested residue. Addition of arabinofuranosidase to the xylanase- and cellulase-supplemented corn increased (P < 0.05) the IVDDM (87.7 vs. 88.3%) and solubilized some NSP of the undigested residue regardless of the dosage level. Increasing the arabinofuranosidase dosage level from 4,000 to 40,000 U/kg reduced (P < 0.05) the total NSP in the undigested residue from 19.1 to 12.6%, but unaffected the IVDDM for corn. Addition of feruloyl esterase to a xylanase- and cellulase-supplemented corn improved (P < 0.05) the IVDDM (87.7 vs. 88.3%) and solubilized some of the galactose, glucose, mannose, total NSP in the undigested residue. Increasing feruloyl esterase dosage level from 35 to 350 U/kg unaffected the IVDDM but increased (P < 0.05) the solubilization of glucose-containing NSP. Addition of acetyl xylan esterase to xylanase, cellulase, arabinofuranosidase and feruloyl esterase-supplemented corn tended (P < 0.10) to improve the IVDDM for corn and increased (P < 0.05) the solubilization of arabinoxylans in the undigested residue. In conclusion, the pancreatin dosage level of 200 mg/g may not be adequate for porcine in vitro digestion of corn. Xylanase and cellulase can increase the porcine IVDDM for corn partly through release of some glucose from the NSP. Arabinofuranosidase can increase the porcine IVDDM for xylanase and cellulase-supplemented corn through release of some glucose from the NSP. Feruloyl esterase can increase IVDDM for xylanase and cellulase-supplemented corn by releasing glucose, arabinose and xylose from the NSP. Dosage of arabinofuranosidase and feruloyl esterase had limited effects on corn digestibility. The addition of acetyl xylan esterase to xylanase-, cellulase-, arabinofuranosidase- and feruloyl esterase-supplemented corn can increase IVDDM by releasing some arabinose and xylose from NSP.