木聚糖酶對飼喂黑麥和小麥日糧生長豬回腸食糜粘度、纖維、營養物質消化率的影響

畜牧編輯

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

　　木聚糖酶對飼喂黑麥和小麥日糧生長豬回腸食糜粘度、纖維、營養物質消化率的影響

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

　　本論文開展兩個試驗研究木聚糖酶對回腸食糜粘度、體內纖維溶解度和降解率、黑麥和小麥纖維組分、有機物、粗蛋白、淀粉和粗脂肪的表觀回腸消化率（AID）的影響。試驗一，日糧為粗粉碎黑麥，8頭去勢公豬（初始體重30.9±0.3kg），四個試驗處理分別為對照組、木聚糖（黑曲霉）組（AN）、木聚糖（枯草芽孢桿菌）組（BS）、木聚糖（里氏木霉）組（TR），試驗為4×4雙拉丁方設計，每期試驗7天。試驗二，試驗為2（復合酶添加與否）×3（細粉碎黑麥、細粉碎小麥、粗粉碎小麥）雙因子設計，復合酶為枯草芽孢桿菌和里氏木霉木聚糖酶復合產品，6頭試驗豬（初始重33.6±0.5kg），試驗豬只為6×6拉丁方試驗設計，每期試驗7天，第5、7天每天收集回腸食糜8小時。日糧中添加0.2%三氧化二鉻為內源指示劑。試驗一結果表明TR組將回腸食糜濃度從對照組的9.3mPa•s降低至6.0mPa•s（P＜0.001），而AN和BS組無影響。所有酶制劑對液體食糜中總阿拉伯木聚糖、高分子阿拉伯木聚糖（HMW-AX）和阿拉伯木聚寡糖（AXOS）含量無影響。試驗二結果表明，復合酶降低了三種谷物日糧的食糜濃度（P＜0.05），但是細粉碎黑麥降低程度（7.6mPa•s）遠高于細粉碎小麥和粗粉碎小麥（＜1.7mPa•s）。與此同時，細粉碎小麥和粗粉碎小麥菌能提高液體食糜中阿拉伯木聚糖的含量（分別為82.4%和45.9%，P＜0.002和0.006），復合酶將液體食糜中阿拉伯木聚寡糖提高16倍。而酶對黑麥阿拉伯木聚糖含量無顯著影響。酶的添加同時能提高液體食糜中低聚木糖含量，但是只有小麥組木糖含量提高了3.9倍（P＜0.001）。試驗一中木聚糖酶對黑麥阿拉伯木聚糖回腸表觀消化率無影響。試驗二，復合酶分別提高了91%黑麥和107%小麥阿拉伯木聚糖回腸表觀消化率（P＜0.001）。酶的添加提高細粉碎小麥淀粉和粗脂肪的回腸表觀消化率（P＜0.012），對其他營養物質的消化率無影響。總之，試驗結果表明木聚糖酶降解小麥阿拉伯木聚糖的效率比黑麥高。

　　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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