Abstract: A study of the biochemical changes induced by natural fermentation of dry cornstalk, wheat straw, and rice straw shows that the fermenting cornstalk smells sweet with pH value diminishing quickly and remaining down below 4.2 hereon. Thirteen volatile fermentation products emerge, chiefly ethanol, acetic acid, lactic acid, and glycerol which improve the fermenting quality. As for the wheat and rice straws, their textures are rude and substantial, the fermenting products smells bad and their pH values diminish insignificantly. The 20 or more kinds of volatile products of fermentation include limited concentrations of acetic acid and lactic acid but a lot more substances like butyric acid which impairs the fermentation quality. Usually, the content of water-soluble carbohydrates (WSC) in the fermenting stuff reflects in certain extent its quality. The pH value diminishes quickly at the beginning of the fermentation with WSC oozing, and remain the same amount in the later stage. When the WSC content is scarce at the initial stage of the fermentation, the pH value diminishes slowly while the WSC content tapers off.

Key words: Fermented feed, Dry stalk or straw, GCMS, Biochemical changes

摘要： 测定玉米、小麦、水稻干秸秆在自然发酵中的生化变化.结果表明:玉米秸秆气味香甜,pH下降迅速并保持在4.2以下,挥发性发酵产物种类有13种,主要为乙醇、乙酸、乳酸及甘油等利于提高饲料品质的物质;而小麦和水稻秸秆质地生硬,生料气味,pH下降困难,挥发性发酵产物多达20种,其中乳酸和乙酸较少,而产生丁酸等影响发酵品质的物质较多;发酵物中可溶性糖含量的变化在一定程度上反映其优劣;当发酵初期可溶性糖较多时,pH下降迅速,后期可溶性糖含量平稳;而当初期可溶性糖含量较低时,pH下降缓慢,后期可溶性糖含量则一直下降.

关键词: 发酵饲料, 干秸秆, 气质联机, 生化变化