132 A longer adaptation time increased xylanases efficacy in improving dry matter and fiber digestibility in the small intestine of growing pigs fed insoluble fiber
Abstract The objective of this experiment was to investigate xylanase efficacy and impact of adaptation time on nutrient utilization in the small intestine of growing pigs fed insoluble fiber. Twenty gilts (30.6 ± 0.2 kg BW; n=5 per treatment) were surgically fitted with t-cannulae in the medial jejunum (292 ± 12 cm distal to the pyloric sphincter) and in the terminal ileum, housed individually, and randomly assigned to one of four dietary treatments: a low-fiber control (LF; 7.3% NDF), a 30% corn bran high-fiber control (HF; 27.2% NDF), HF + 100 mg xylanase/kg (HF+XY; Econase XT 25P; AB Vista, Marlborough, UK), and HF + 50 mg arabinoxylan-oligosaccharide/kg (HF+AX; 3-7 degrees of polymerization). Gilts were limit fed for three 17 d periods (P1, P2, or P3). Each period included 5 d of adaptation, 2 d of fecal collections, 3 d of ileal collections, and 3 d of jejunal collections. Data were analyzed as repeated records using a linear mixed model (PROC Mixed, SAS 9.4) with surgery date as a random effect, and treatment, period, and their interaction as fixed effects. There tended to be a treatment by period interaction for the apparent jejunal digestibility (AJD) of DM driven by HF+XY improving digestibility over time when compared to HF. Xylanase improved AJD of DM by 21.9% (12.04% vs. 15.4%) in P2, and 40.5% (12.18% vs. 20.49%) in P3 (Treatment Period, P = 0.054). Xylanase supplementation improved AJD of NDF, compared to HF, in P2 by 36.3% (13.7% vs. 21.5%), and in P3 by 28.6% (17.7 vs 24.8%; Treatment Period, P = 0.031). Supplementing xylanase improved the apparent ileal digestibity (AID) of DM over HF in P1 by 4.4%, in P2 by 3.7% (73.91% vs. 76.2 %), and in P3 by 7.4% (75.04% vs. 80.84%; Treatment Period P=0.043). In conclusion xylanase efficacy improved with increased adaptation time.