添加丙酸对青稞秸秆和多年生黑麦草混合青贮发酵品质及有氧稳定性的影响

Effects of Adding Propionic Acid on Fermentation Quality and Aerobic Stability of Mixed Silage of Hullessbarley Straw and Perennial Ryegrass in Tibet

为探讨不同水平丙酸对青稞(Hordeum vulgare)秸秆和多年生黑麦草(Lolium perenne)混合青贮发酵品质及有氧稳定性的影响,试验设0(CK),0.3%(PA3),0.4%(PA4)和0.5%丙酸(PA5)4个处理组。青贮后第30 d开窖取样测定发酵品质,并有氧暴露12 d分析有氧稳定性。结果表明:各组pH值、乳酸和干物质含量差异不显著,但丙酸添加组乳酸/乙酸(除PA3组)和水溶性碳水化合物含量显著高于对照组(P<0.05),氨态氮/总氮和丁酸含量显著低于对照组(P<0.05)。有氧暴露阶段,PA4和PA5组pH值与对照组和PA3组相比上升幅度较小,乳酸、干物质含量损失较少,且水溶性碳水化合物含量随着丙酸添加量的增大而升高。随着暴露时间延长,各组氨态氮/总氮值和丁酸含量逐渐升高,且PA4和PA5组显著低于对照组和PA3组(P<0.05)。表明添加0.4%以上的丙酸能够改善混合青贮饲料的发酵品质和有氧稳定性。

This study was carried out to evaluate the effects of adding propionic acid on the fermentation quality and aerobic stability of mixed silages of hullessbarley straw and perennial ryegrass. There were three treatments of different propionic acid addition ratios （0.3%, 0.4% or 0.5% of fresh weight） plus a control. Silos were opened on 30th day of ensiling, six silos per treatment were used for fermentation quality determination, and other silages were exposed to the air for 12 days and subjected to an aerobic stability evaluation. The results showed that the fermentation quality of all treatments were well. There were no significant difference in pH value , lactic acid and dry matter contents among all treatments, however, lactic acid/acetic acid and water soluble carbohydrate in propionic acid treatments （except PA3） were significantly higher than control（P〈0.05） . The propionic treatments showed significantly lower ammonia-N/total-N and butyric acid content compared with control（P〈0.05）. During aerobic exposure, the pH value of 0.4% and 0.5 % propionic acid addition increased more slowly than that of control and 0.3 % propionic acid addition silages. The lactic acid, water soluble carbohydrate and dry matter content decreased gradually during aerobic exposure, and increased with propionic acid addition ratio. The value of ammonia-N/total-N and butyric acid content of all silages increased during aerobic exposure, and these of 0.4% and 0.5% propionic acid addition silages were always significantly lower than control and 0.3% addition silages（P〈0.05）. These results indicated that adding 0.4% or above propionic acid could improve the fermentation quality and aerobic stability of the mixed silage.