PSVII-10 Xylanase improved the nutrient and energy digestibility of diets high in insoluble corn fiber fed to swine following a 36-d dietary adaptation period

Abstract The efficacy of xylanase in practical swine diets is inconsistent and poorly understood. The experimental objective was to investigate the efficacy of xylanase in growing pigs fed a diet high in insoluble corn fiber and afforded a longer adaptation period than typically reported in the literature. Sixty gilts (25.43 ± 0.88 kg BW; L337 X Camborough, PIC, Hendersonville, TN; n = 15 per treatment), were blocked by weight, housed individually, and randomly assigned to one of four dietary treatments: a low-fiber control (LF; 8.45% NDF), a 30% corn bran high-fiber control (HF; 24.5% NDF), HF + 100 mg/kg of xylanase (HF+XY; Econase XT 25P; AB Vista, Marlborough, UK), and HF + 50 mg/kg of arabinoxylan-oligosaccharide (HF+AX; 3-7 degrees of polymerization). Diets contained 0.5% chromium (III) oxide. Gilts were fed ad libitum for 36 d, followed by a 7-d period of adaptation to limit feeding (80% of average ad libitum intake) and housing in metabolism crates, followed by 3 d of urine and fecal collection. Data were analyzed using PROC MIXED (SAS; 9.4) as a randomized complete block design with pig as the experimental unit, block and replicate as random effects, and treatment as a fixed effect. Compared to the LF diet, the HF diet reduced the apparent total tract digestibility (ATTD) of DM (88.7 vs. 75.6%), GE (89.0 vs. 77.4%), CP (87.2 vs. 81.8%), NDF (63.3 vs. 44.4%), ADF, and hemicellulose (P = 0.01). Xylanase supplementation, but not arabinoxylan-oligosaccharide, when compared to the HF control diet, improved the ATTD of DM by 3.3% (78.2 vs. 75.6%), GE by 2.2% (79.1 vs. 77.4%), CP by 2.9% (84.2 vs. 81.8%), NDF by 17.5% (53.9 vs. 44.4%), ADF by 16.3% (52.1 vs. 42.9%), and hemicellulose by 16.4% (P < 0.05). These data indicate insoluble fiber reduced nutrient and energy digestibility, but xylanase was effective in partially mitigating that effect.