Nortey T N, Patience J F, Sands J S, Trottier N L, Zijlstra R T
Prairie Swine Centre Inc., Saskatoon, Saskatchewan, Canada.
J Anim Sci. 2008 Dec;86(12):3450-64. doi: 10.2527/jas.2007-0472. Epub 2008 Aug 1.
Wheat by-products are feedstuffs that vary in nutritional value, partly because of arabinoxylans that limit nutrient digestibility. Millrun is a byproduct from dry milling wheat into flour and contains varying amounts of the bran, middlings, screening, and shorts fractions. The digestible nutrient content of mill-run is not well known. Effects of xylanase supplementation (0 or 4,000 units/kg of diet) on energy, AA, P, and Ca digestibilities were studied in a wheat control diet and 5 diets containing 30% of a by-product (mill-run, middlings, shorts, screening, or bran) in a 2 x 6 factorial arrangement of treatments. The wheat control diet was formulated to contain 3.34 Mcal of DE/kg and 3.0 g of standardized ileal digestible Lys/Mcal of DE. Diets contained 0.4% chromic oxide. Each of 12 ileal-cannulated pigs (32.5 +/- 2.5 kg) was fed 6 or 7 of 12 diets at 3 times the DE requirement for maintenance in successive 10-d periods for 6 or 7 observations per diet. Feces and ileal digesta were each collected for 2 d. Xylanase tended to increase (P < 0.10) ileal energy digestibility by 2.2 percentage units and the DE content by 0.10 Mcal/kg of DM and increased (P < 0.05) ileal DM digestibility by 2.8 percentage units; a diet x xylanase interaction was not observed. Xylanase increased (P < 0.05) total tract energy and DM digestibilities and the DE content. A diet x xylanase interaction was observed; xylanase increased (P < 0.05) total tract energy digestibility of the millrun diet from 72.1 to 78.9%, DE content from 3.19 to 3.51 Mcal/kg of DM, and DM digestibility from 71.5 to 78.6%. Diet affected (P < 0.05) and xylanase improved (P < 0.05) digestibility and digestible contents of some AA in diets and by-products, including Lys, Thr, and Val. Xylanase increased (P < 0.05) Lys digestibility by 13.8, 5.0, 5.2, 6.0, and 14.1 percentage units in millrun, middlings, shorts, screening, and bran, respectively. Diet affected (P < 0.01) total tract P and Ca digestibilities. Xylanase increased (P < 0.05) digestible P and Ca contents. In summary, nutrient digestibility varies among wheat by-products. Millrun contained 2.65 Mcal of DE/kg of DM, which xylanase increased to 3.56 Mcal of DE/kg of DM. Xylanase improved nutrient digestibility and DE content in wheat by-products; and the extent of improvement depended on the by-product. Xylanase supplementation may maximize opportunities to include wheat byproducts in swine diets and ameliorate reductions in nutrient digestibility that may be associated with arabinoxylans.
小麦副产品作为饲料原料，其营养价值各异，部分原因在于阿拉伯木聚糖会限制养分消化率。磨粉厂下脚料是干磨小麦制粉过程中的副产品，包含不同比例的麸皮、粗粉、筛屑和细麸等部分。磨粉厂下脚料的可消化养分含量尚不清楚。本研究采用2×6析因试验设计，以小麦对照日粮和5种分别含有30%某种副产品（磨粉厂下脚料、粗粉、细麸、筛屑或麸皮）的日粮为研究对象，探讨添加木聚糖酶（0或4000单位/千克日粮）对能量、氨基酸、磷和钙消化率的影响。小麦对照日粮的配制目标为每千克含3.34兆卡消化能以及每兆卡消化能含3.0克标准回肠可消化赖氨酸。日粮中氧化铬含量为0.4%。选取12头安装了回肠瘘管的猪（体重32.5±2.5千克），在连续的10天周期内，按照维持所需消化能的3倍，每种日粮投喂6或7次，每种日粮进行6或7次观测。粪便和回肠食糜均采集2天。木聚糖酶使回肠能量消化率有提高趋势（P<0.10），提高了2.2个百分点，消化能含量每千克干物质增加0.10兆卡，回肠干物质消化率提高（P<0.05）2.8个百分点；未观察到日粮与木聚糖酶的交互作用。木聚糖酶提高了（P<0.05）全肠道能量和干物质消化率以及消化能含量。观察到日粮与木聚糖酶的交互作用；木聚糖酶使磨粉厂下脚料日粮的全肠道能量消化率从72.1%提高到78.9%，消化能含量从每千克干物质3.19兆卡提高到3.51兆卡，干物质消化率从71.5%提高到78.6%。日粮影响（P<0.05）且木聚糖酶改善（P<0.05）了日粮及副产品中某些氨基酸的消化率和可消化含量，包括赖氨酸、苏氨酸和缬氨酸。木聚糖酶使磨粉厂下脚料、粗粉、细麸、筛屑和麸皮中的赖氨酸消化率分别提高（P<0.05）13.8、5.0、5.2、6.0和14.1个百分点。日粮影响（P<0.01）全肠道磷和钙的消化率。木聚糖酶提高了（P<0.05）可消化磷和钙的含量。总之，小麦副产品间的养分消化率存在差异。磨粉厂下脚料每千克干物质含2.65兆卡消化能，木聚糖酶使其提高到每千克干物质3.56兆卡消化能。木聚糖酶提高了小麦副产品的养分消化率和消化能含量；改善程度取决于副产品种类。添加木聚糖酶可能会最大程度地增加在猪日粮中使用小麦副产品的机会，并缓解可能与阿拉伯木聚糖相关的养分消化率降低问题。
