Date Full Report Received


Date Abstract Report Received



Primary Investigator:

The increasing industrial demand for feed grains, partly for biofuel production, has raised the price forecast for feed grains. Co-products are a short-term solution for commercial swine production to control feed cost, but these co-products have substantial amounts of fiber that decrease nutrient digestibility in pigs. Application of fiber degrading enzymes and liquid feeding methods may help to improve the nutritional value of fibrous feed ingredients. The objective of this study was to evaluate the effect of endo-1,4-β-xylanase supplementation (Xyl; with or without), feeding method (dry or liquid) and feedstuff (corn DDGS or wheat middlings) on digestibility of energy and nutrients, intestinal morphology, cecal pH and volatile fatty acids concentrations in growing pigs. Sixty-four pigs (BW 25.9 ± 0.38 kg) were blocked by BW and sex, placed in individual pens and randomly assigned to 8 dietary treatments. Within each feedstuff, diets were fed either liquid or dry, without or with Xyl (24,000 BXU/kg feed). DDGS and wheat middlings-based diets contained 3.32 and 3.19 Mcal/kg ME and 1.03 and 1.07% standardize ileal digestible) lysine, respectively. Pigs were fed equal amounts of ME per day and restricted at 3 times maintenance energy requirements (197 kcal ME/kg BW0.60). The daily ration was fed in 2 equal meals. Liquid diets were prepared by steeping DDGS or wheat middlings with water (1:3 weight:volume) with or without Xyl for 24 h, followed by mixing with the respective basal diet and water to achieve a final ratio of 1:2.5 w:v. Diets were fed for 16 days and then pigs were euthanized. Supplementation of Xyl to dry wheat middlings-based diets increased ileal digestibility of GE and NDF as compared to dry wheat middlings-based diets without Xyl (64.50 vs. 54.67%; 52.88 vs. 31.69%, respectively), but this was not the case for pigs fed liquid diets. Supplementation of Xyl in liquid DDGS-based diets improved ileal digestibility of NDF as compared to liquid DDGS-based diets without Xyl, but Xyl did not affect ileal digestibility of NDF in dry DDGS diets. Addition of Xyl to wheat middlings-based diets improved fecal digestibility of GE and N as compared to wheat middlings diets without Xyl (80.37 vs. 78.07%; 80.23 vs. 77.94%, respectively); however, there was no effect of Xyl in DDGS based diets (feedstuff by Xyl interaction, P < 0.05). DDGS diets in liquid form reduced fecal digestibility of GE as compared to DDGS diets offered in dry form (81.10 vs. 82.97%); however, no effects were observed when wheat middlings diets were offered, regardless of the feeding method (78.89 vs. 79.55%; feeding method by feedstuff interaction, P = 0.010). Pigs fed DDGS diets had greater concentrations of butyrate in the cecum (P = 0.001) as compared to pigs fed wheat middlings diets (27.55 vs. 20.44 mmol/L). Pigs fed DDGS-based diets with Xyl had deeper crypts in the jejunum than pigs fed DDGS diets without Xyl (98.20 vs. 86.16 µm), however, there was no effect of Xyl in pigs fed wheat middlings-based diets. Under the conditions of this experiment, the liquid feeding method and the application of Xyl demonstrated limited potential to enhance nutrient digestibility in pigs fed corn DDGS-based diets. However, supplementation of Xyl in wheat middlings-based diets improved the ileal digestibility of GE and NDF and fecal digestibility of GE and N. Liquid feeding as a pretreatment did not enhance further the nutritional value of wheat middling based diets.
Key Findings:
• The results indicate that when DDGS-based diets were fed, neither addition of the enzyme xylanase nor feeding method (dry or liquid) appeared to improve the total tract and ileal digestibility of nutrients. Thus, xylanase did not increase the amount of energy or nutrients available to the pigs, which may have been related to the complex nature of the cell wall structure of DDGS (making it inaccessible to the enzyme).
• Supplementation of xylanase had a clear positive effect on the total tract digestibility of energy and nitrogen and on the ileal digestibility of energy and NDF when supplemented to wheat middlings-based diets. This improves the nutritional value of wheat middlings in pig diets.
• Pre-steeping DDGS or wheat middlings with enzymes (to increase the opportunity for the enzyme to interact with the feedstuffs and promote degradation of fiber) and feeding the diets in liquid form did not improve the nutritional value of DDGS or wheat middlings. Under the conditions of this study, pre-steeping as a processing step or liquid feeding did not prove to be beneficial.
Contact: Eric van Heugten
North Carolina State University
Box 7621
Raleigh, NC 27695-7621
Phone: (919) 513 1116
E-mail: Eric_vanHeugten@ncsu.edu