Unveiling the influence of adaptation time on xylanase and arabinoxylan-oligosaccharide efficacy: a study on nutrient digestibility, viscosity, and scanning electron microscopy in the small and large intestine of growing pigs fed insoluble fiber

Abstract

The experiment objective was to evaluate the impact of xylanase over time on viscosity and digestibility in growing pigs fed corn-based fiber. Twenty gilts with an initial body weight of 30.6 ± 0.2 kg (n = 5 per dietary treatment) were fitted with t-cannulae in the medial jejunum and terminal ileum, housed individually, and randomly assigned to one of four dietary treatments: low-fiber control (LF) with 10.4% total dietary fiber (TDF), 30% corn bran high-fiber control (HF; 26.4% TDF), HF + 100 mg xylanase/kg (XY; Econase XT 25P; AB Vista, Marlborough, UK), and HF + 50 mg arabinoxylan-oligosaccharide/kg (AX). Gilts were limit fed for three 17 d periods (P1, P2, P3); each included 5 d adaptation, 2 d fecal collection, 3 d ileal collection, 3 d jejunal collection, and 4 d related rate of passage study. Data were analyzed as repeated measures using a linear mixed model with surgery date as a random effect, and dietary treatment, period, and their interaction as fixed effects. Jejunal and ileal digesta viscosity did not differ among dietary treatments or periods (P > 0.10). There was a dietary treatment × period interaction for the apparent jejunal digestibility (AJD) of dry matter (DM), gross energy (GE), insoluble dietary fiber (IDF), neutral detergent fiber (NDF), total arabinoxylan (T-AX), total non-starch polysaccharide (T-NSP), and TDF (P≤ 0.05). In P1, LF had the greatest AJD of DM (15.5%), and relative to HF and AX, XY decreased it (9.3%, 10.1 %, and 6.3%, respectively). In P2, the AJD of DM in XY was greater than HF (11.7% vs. 9.1%) but did not differ from AX (10.5%). Relative to HF, in P3, XY increased AJD of DM (11.7 vs 15.3%), and AX decreased it (7.2%). For the AJD of NDF, AX performed intermediately in P1; in P2, relative to HF, XY, and AX increased the AJD of NDF (8.4%, 13.1%, and 11.7%, respectively), and in P3, XY, and LF did not differ (13.6 vs. 14.4%). A similar response was observed for the AJD of IDF and TDF, except for XY having the greatest AJD of IDF, T-AX, T-NSP, and TDF in P3 (P < 0.05). Compared to LF, irrespective of period, HF decreased the apparent ileal digestibility (AID) and apparent total tract digestibility (ATTD) of IDF, TDF, and NDF (P < 0.05). Relative to HF, XY partially mitigated this effect, improving the AID and ATTD of TDF, IDF, and NDF (P < 0.05). Increased corn-based fiber decreased nutrient digestibility, but XY partially mitigated that effect in the small intestine through enhanced fiber digestibility when given sufficient adaptation time.

Keywords: adaptation time; corn fiber; ileal digestibility; jejunal digestibility; swine; xylanase.

Figure 1.

The relationship between viscosity measured at a given shear rate for jejunal and ileal digesta. (A) The impact of dietary treatment on the viscosity of jejunal digesta. (B) The effect of period on the viscosity of jejunal digesta. (C) The impact of dietary treatment on the viscosity of ileal digesta. (D) The effect of period on the viscosity of ileal digesta.

Figure 2.

The simple effects of dietary treatment by period on the apparent jejunal digestibility (AJD) of dry matter (DM) and gross energy (GE).

Figure 3.

The simple effects of dietary treatment by period on the apparent jejunal digestibility (AJD) of neutral detergent fiber (NDF), insoluble dietary fiber (IDF), and total dietary fiber (TDF).

Figure 4.

The simple effects of dietary treatment by period on the apparent jejunal digestibility (AJD) of total arabinoxylan-oligosaccharide (T-AX) and total non-starch polysaccharide (T-NSP).

Figure 5.

The main effects of dietary treatment and period for the apparent jejunal digestibility (AJD) of acid detergent fiber (ADF).

Figure 6.

The simple effects of dietary treatment by period on the apparent ileal digestibility (AID) of dry matter (DM) and gross energy (GE).

Figure 7.

Field emission scanning electron microscopy images (100×) of corn bran, and jejunal digesta from pigs fed high-fiber dietary treatment (HF), HF plus xylanase (XY), and HF plus arabinoxylan oligosaccharide (AX) in P1, P2, and P3. Representative images were selected by a research technician blinded to treatments.

Figure 8.

Field emission scanning electron microscopy images (100×) of corn bran, and ileal digesta from pigs fed the high-fiber dietary treatment (HF), HF plus xylanase (XY), and HF plus arabinoxylan oligosaccharide (AX) in periods 1, 2 and 3 (P1, P2, and P3). Representative images were selected by a research technician blinded to treatments.