木聚糖酶对饲喂黑麦和小麦日粮生长猪回肠食糜粘度、纤维、营养物质消化率的影响

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　　2015. J. Anim. Sci. 93(9): 4323-4335

　　木聚糖酶对饲喂黑麦和小麦日粮生长猪回肠食糜粘度、纤维、营养物质消化率的影响

　　H. N. Lærke, S. Arent, S. Dalsgaard和K. E. Bach Knudsen

　　本论文开展两个试验研究木聚糖酶对回肠食糜粘度、体内纤维溶解度和降解率、黑麦和小麦纤维组分、有机物、粗蛋白、淀粉和粗脂肪的表观回肠消化率（AID）的影响。试验一，日粮为粗粉碎黑麦，8头去势公猪（初始体重30.9±0.3kg），四个试验处理分别为对照组、木聚糖（黑曲霉）组（AN）、木聚糖（枯草芽孢杆菌）组（BS）、木聚糖（里氏木霉）组（TR），试验为4×4双拉丁方设计，每期试验7天。试验二，试验为2（复合酶添加与否）×3（细粉碎黑麦、细粉碎小麦、粗粉碎小麦）双因子设计，复合酶为枯草芽孢杆菌和里氏木霉木聚糖酶复合产品，6头试验猪（初始重33.6±0.5kg），试验猪只为6×6拉丁方试验设计，每期试验7天，第5、7天每天收集回肠食糜8小时。日粮中添加0.2%三氧化二铬为内源指示剂。试验一结果表明TR组将回肠食糜浓度从对照组的9.3mPa•s降低至6.0mPa•s（P＜0.001），而AN和BS组无影响。所有酶制剂对液体食糜中总阿拉伯木聚糖、高分子阿拉伯木聚糖（HMW-AX）和阿拉伯木聚寡糖（AXOS）含量无影响。试验二结果表明，复合酶降低了三种谷物日粮的食糜浓度（P＜0.05），但是细粉碎黑麦降低程度（7.6mPa•s）远高于细粉碎小麦和粗粉碎小麦（＜1.7mPa•s）。与此同时，细粉碎小麦和粗粉碎小麦菌能提高液体食糜中阿拉伯木聚糖的含量（分别为82.4%和45.9%，P＜0.002和0.006），复合酶将液体食糜中阿拉伯木聚寡糖提高16倍。而酶对黑麦阿拉伯木聚糖含量无显著影响。酶的添加同时能提高液体食糜中低聚木糖含量，但是只有小麦组木糖含量提高了3.9倍（P＜0.001）。试验一中木聚糖酶对黑麦阿拉伯木聚糖回肠表观消化率无影响。试验二，复合酶分别提高了91%黑麦和107%小麦阿拉伯木聚糖回肠表观消化率（P＜0.001）。酶的添加提高细粉碎小麦淀粉和粗脂肪的回肠表观消化率（P＜0.012），对其他营养物质的消化率无影响。总之，试验结果表明木聚糖酶降解小麦阿拉伯木聚糖的效率比黑麦高。

　　Effect of xylanases on ileal viscosity, intestinal fiber modification, and apparent ileal fiber and nutrient digestibility of rye and wheat in growing pigs

　　H. N. Lærke, S. Arent, S. Dalsgaard and K. E. Bach Knudsen

　　Two experiments were performed to study the effect of xylanase on ileal extract viscosity, in vivo fiber solubilization and degradation, and apparent ileal digestibility (AID) of fiber constituents, OM, CP, starch, and crude fat in rye and wheat in ileal-cannulated pigs. In Exp. 1, coarse rye without (NX) or with addition of xylanase from Aspergillus niger (AN), Bacillus subtilis (BS), or Trichoderma reesei (TR) was fed to 8 ileal-cannulated barrows (initial BW 30.9 ± 0.3 kg) for 1 wk each according to a double 4 × 4 Latin square design. In Exp. 2, fine rye, fine wheat, and coarse wheat with or without a combination of xylanase from Bacillus subtilis and Trichoderma reesei were fed to 6 ileal-cannulated barrows (initial BW 33.6 ± 0.5 kg) for 1 wk according to a 6 × 6 Latin square design with a 2 × 3 factorial arrangement of enzyme and cereal matrix. Chromic oxide (0.2%) was used as an inert marker. Ileal effluent was collected for 8 h on d 5 and 7 and pooled for analysis. In Exp. 1, TR reduced intestinal viscosity of pigs fed rye from 9.3 mPa&#8226;s in the control diet (NX) to 6.0 mPa&#8226;s (P < 0.001), whereas AN and BS had no effect. None of the enzymes changed the concentration of total arabinoxylan, high-molecular-weight arabinoxylan (HMW-AX), or arabinoxylan oligosaccharides (AXOS) in the liquid phase of digesta. In Exp. 2, the enzyme combination reduced intestinal viscosity for all 3 cereal matrices (P < 0.05), but the viscosity was much higher with fine rye (7.6 mPa&#8226;s) than with fine and coarse wheat (<1.7 mPa&#8226;s). Simultaneously, the total concentration of arabinoxylan in the liquid phase of digesta increased by 82.4% in fine wheat (P < 0.002) and by 45.9% in coarse wheat (P < 0.006), and AXOS increased 16-fold with enzyme addition. Similar effects of enzyme were not seen with rye. The concentration of xylooligosaccharides in the liquid phase of digesta increased with enzyme addition, but for xylose, it was only significant for wheat, for which it increased 3.9-fold (P < 0.001). None of the xylanases affected AID of arabinoxylan of rye in Exp. 1. In Exp. 2, the enzyme combination increased AID of arabinoxylan by 91% to 107% (P < 0.001) across cereal matrices. Enzyme addition did not affect AID of nutrients in any of the experiments except for a higher starch and crude fat digestibility of fine wheat with enzyme addition (P < 0.012) in Exp. 2. Collectively, the results suggest that xylanase is more efficient in degrading arabinoxylan from wheat than from rye.
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