Abstract
The experimental objective was to investigate the impact of xylanase on the bioavailability of energy, oxidative status, and gut function of growing pigs fed a diet high in insoluble fiber and given a longer adaptation time than typically reported. Three replicates of 20 gilts with an initial body weight (BW) of 25.43 ± 0.88 kg were blocked by BW, individually housed, and randomly assigned to one of four dietary treatments: a low-fiber control (LF) with 7.5% neutral detergent fiber (NDF), a 30% corn bran without solubles high-fiber control (HF; 21.9% NDF), HF + 100 mg/kg xylanase (HF + XY; Econase XT 25P), and HF + 50 mg/kg arabinoxylan-oligosaccharide (HF + AX). Gilts were fed ad libitum for 36 d across two dietary phases. Pigs and feeders were weighed on days 0, 14, 27, and 36. On day 36, pigs were housed in metabolism crates for a 10-d period, limit fed (80% of average ad libitum intake), and feces and urine were collected the last 72 h to determine the digestible energy (DE) and metabolizable energy (ME). On day 46, serum and ileal and colonic tissue were collected. Data were analyzed as a linear mixed model with block and replication as random effects, and treatment, time, and treatment × time as fixed effects. There was a significant treatment × time interaction for BW, average daily gain (ADG), and gain to feed (G:F; P < 0.001). By design, BW at day 0 did not differ; at day 14, pigs fed LF were 3.5% heavier, and pigs fed HF + XY, when compared with HF, were 4% and 4.2% heavier at days 27 and 36, respectively (P < 0.001). From day 14 to 27 and day 27 to 36, when compared with HF, HF + XY improved ADG by 12.4% and 10.7% and G:F by 13.8% and 8.8%, respectively (P < 0.05). Compared with LF, HF decreased DE and ME by 0.51 and 0.42 Mcal/kg, respectively, but xylanase partially mitigated that effect by increasing DE and ME by 0.15 and 0.12 Mcal/kg, over HF, respectively (P < 0.05). Pigs fed HF + XY had increased total antioxidant capacity in the serum and ileum (P < 0.05) and tended to have less circulating malondialdehyde (P = 0.098). Pigs fed LF had increased ileal villus height, and HF + XY and HF + AX had shallower intestinal crypts (P < 0.001). Pigs fed HF + XY had increased ileal messenger ribonucleic acid abundance of claudin 4 and occludin (P < 0.05). Xylanase, but not AX, improved the growth performance of pigs fed insoluble corn-based fiber. This was likely a result of the observed increase in ME, improved antioxidant capacity, and enhanced gut barrier integrity, but it may require increased adaptation time to elicit this response.
Highlights
Dietary energy impacts nearly every performance metric in pork production (Beaulieu et al, 2009), and meeting the specification for dietary energy accounts for more than 60% of the input cost of raising one hog to market (Patience, 2017)
By design, body weight (BW) at day 0 did not differ among treatments, at day 14, pigs in the low-fiber control (LF) treatment were 3.5% heavier, and pigs fed xylanase, when compared with high-fiber control (HF), were 4% and 4.2% heavier at days 27 and 36, respectively (P < 0.05)
Non-starch polysaccharides (NSP) are often considered an antinutritional factor in swine diets associated with reduced energy and nutrient utilization, decreased growth performance, and reduced carcass yield (Weber et al, 2015; Acosta et al, 2020)
Summary
Dietary energy impacts nearly every performance metric in pork production (Beaulieu et al, 2009), and meeting the specification for dietary energy accounts for more than 60% of the input cost of raising one hog to market (Patience, 2017). One approach to reduce this cost is to improve the energetic contribution of dietary components that supply energy: protein, fat, simple carbohydrates, and fiber. Of these four, fiber has the greatest opportunity for improvement. Swine diets in the United States contain between 8% and 20% fiber, generally insoluble and corn-based, and within these diets, the contribution of fiber to energy is estimated to be less than 4%, irrespective of the energy system (Patience and Petry, 2019). One strategy to improve the energetic contribution of fiber is to include carbohydrases, such as xylanase, into the formulation matrix. Xylanase hydrolyzes the β-(1-4) glycosidic bonds of arabinoxylan by releasing a mixture of xylose, arabinose, and xylooligosaccharides that can be either absorbed or fermented by the pig (Dodd and Cann, 2009), but its efficacy in corn-based diets is inconsistent and poorly understood
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