玉米秸秆不同部位主要化学成分和活体外消化率比较

Comparison of main chemical composition and in vitro digestibility in various sections of corn stalks

本试验测定了“农大108”玉米秸秆不同部位的主要化学成分含量、活体外消化率和瘤胃微生物发酵产气量,结果表明:秸秆各部位间存在显著差异(P<0.05),其中总糖含量以茎节、茎皮中最高(分别达到20.7%和19.3%),粗脂肪含量也在茎节和茎皮中最高(分别为5.8%和5.2%),而茎髓中的含量最少;粗蛋白质含量则是叶片中最高(14.9%),茎髓次之;粗灰分、Ca和P含量均以叶片中最高(分别为10.5%、1.03%和0.1%);中性洗涤纤维(NDF)在苞叶中含量最高(77.1%);酸性洗涤纤维(ADF)和木质素含量均以茎皮中最高(分别为52.0%和14.4%),苞叶中最低(分别为38.2%和6.7%)。阉牛活体外对DM、NDF和ADF消化率都以茎皮为最低、苞叶为最高;阉牛活体外瘤胃微生物发酵产气量以苞叶最高,其次为茎髓、叶片、叶鞘和茎节,而茎皮最少。综合比较得出,玉米秸秆各部位的营养价值存在明显差异,从高到低的排序为:苞叶>茎髓>叶片>叶鞘>茎节>茎皮。

Using corn （var. Nongda 108） as experimental material, various sections of stalks were compared for their chemical composition, in vitro digestibility and gas production. The results showed that there was significantly difference （P〈0.05） among sections. The stem nodes and barks had highest content of total carbohydrates （20.7% and 19.3%, respectively） and of ether extract （5.8% and 5.2%, respectively）. The stem pith contained the lowest ether extract. The highest content of crude protein was found in leaf blades （14.9%）, followed by that in stem pith. Leaf blade accumulated 10.5 % of ash, 1.03 % of Ca and 0.1 % P, A concentration of 77.1 % NDF was found in ear husks, whereas 52.0%ADF and 14.4% lignin were localized in stem barks. When steers were used as experimental animals, the ear husk exhibited highest in vitro digestibilities of dry matter, NDF and ADF, and stem barks was lost. More in vitro gas production occurred in ear husk, followed respectively by stem pith, leaf blade, leaf sheath, stem node and stem bark. It was concluded that different sections of corn stalks contained different nutritive values, ranked as follows： ear husk 〉 stem pith 〉 leaf blade 〉 leaf sheath 〉 stem node 〉 stem bark.