Dietary D-xylose effects on growth performance and portal-drained viscera nutrient fluxes, insulin production, and oxygen consumption in growing pigs

Abstract Text:

Addition of xylanase to pig diets rich in insoluble fiber can promote nutrient digestibility and pig performance. However, high doses of xylanase could result in high xylose release, particularly in diets with high cereal co-products, which are rich in xylose. It is well documented that free dietary xylose has negative effects in non-ruminants. However, the amount of xylose that could elicit such adverse effects is not known in pigs. Thus, 2 experiments were conducted to investigate the effects of dietary D-xylose on growth performance and portal-drained viscera (PDV) fluxes of glucose (GLU), essential AA (EAA), urea-N (BUN), insulin production, and O₂ consumption in growing pigs. In Exp. 1, 32 pigs (21.4 ± 0.1 kg BW; 8 pigs per diet) were used to determine the effects of replacing 25% cornstarch (CS) with D-xylose (w/w basis; 0, 5, 15, and 25%) in corn-soybean meal-based diet on pig performance in a 28-d trial. The results indicated that up to 15% dietary D-xylose did not reduce (P > 0.10) pig performance, whereas replacing 25% of CS with 25% D-xylose resulted in a 10%-unit decline (P < 0.05) in body weight and feed efficiency. In Exp. 2, six portal-vein catheterized gilts (22.8 ± 1.6 kg BW) were fed the 0 and 15% D-xylose diets at 4% of their BW once daily at 0900 h for 7 d in a cross-over design (6 pigs per diet). On d 7, para-amino hippuric acid was infused into the ileal vein to measure blood flow rate (BFR), whereas blood was sampled from the portal vein and carotid artery for 6 h, postprandially, to assay GLU, O₂, BUN, insulin, and EAA concentrations. Diet had no effect (P > 0.10) on postprandial BFR, insulin production, and portal BUN and AA fluxes. In addition, diet had no effect (P > 0.10) on postprandial portal AA concentrations. Pigs fed 0% D-xylose had greater portal and carotid GLU (P < 0.05) and BUN (P < 0.10) concentrations, and portal GLU fluxes (P < 0.05) than pigs fed 15% D-xylose diet. Further, postprandial PDV O₂ consumption was greater (P< 0.05) in pigs fed 0% D-xylose diet than those fed 15% D-xylose. In conclusion, 15% D-xylose did not reduce pig performance, postprandial AA fluxes or increase PDV energetic demand, but reduced glucose fluxes linked to low dietary glucose. However, 25% xylose reduced growth performance in growing pigs.

Keywords: D-xylose diet, performance, net portal flux, nutrients, pig