体外产气法评价不同比例玉米秸秆和甜叶菊秆混贮效果

Evaluation of feeding value for mixed silage of corn straw and stevia straw by in vitro gas production method

摘要:

【目的】探讨玉米秸秆与甜叶菊秆混贮的青贮品质。【方法】采用体外产气法评价玉米秸秆与甜叶菊秆按 100∶0（CK 组）、90∶10（Ⅰ组）、80∶20（Ⅱ组）、70∶30（Ⅲ组）、60∶40（Ⅳ组）和 50∶50（Ⅴ组）比例混贮的效果。【结果】随着体外发酵时间的延长，各组总产气量逐渐升高。其中Ⅰ组产气增长速率最大，48 h 产气量（GP_{48 h}）最高（157. 92 mL/g），且显著高于除Ⅱ组以外的其他组（P＜0. 05）；随发酵时间的延长，各组干物质降解率（DMD）和酸性洗涤纤维降解率（ADFD）逐渐增加，其中Ⅴ组 DMD_{48 h} 和 ADFD_{48 h} 显著低于其他组（P＜0. 05）。随甜叶菊秆添加比例的增加，各处理中性洗涤纤维降解率 （NDFD_{48 h}）和 ADFD_{48 h}呈先增加后降低的趋势。Ⅰ和Ⅱ组 NDFD_{48 h}显著高于其他组（P＜0. 05）。随着甜叶菊秆添加量的增加，发酵液 pH 值降低，各处理 pH 值介于 6. 52~7. 18，且发酵时间与 pH 值呈负相关；发酵液氨态氮（NH₃-N）浓度介于 10. 51~17. 81 mg/dL，在瘤胃微生物活动的适宜浓度范围内；不同处理混合青贮的体外乙酸和丁酸含量差异不显著（P＞0. 05），CK 组丙酸含量与其他组差异显著（P ＜0. 05）。灰色关联度分析表明：不同比例甜叶菊秆和玉米秸秆混合青贮的体外发酵参数关联值为Ⅰ 组＞Ⅲ组＞Ⅱ组＞Ⅳ组＞CK 组＞Ⅴ组。【结论】本试验条件下，玉米秸秆和甜叶菊秆以 90∶10 的比例混合时，发酵效果最优。

Abstract:

In order to study the silage quality of mixed corn stalk and stevia stalk，an in vitro gas production method was used to evaluate the silage feeding value of corn stalk and stevia stalk mixed at 100∶0（CK group），90∶10 （I group），80∶20（II group），70∶30（III group），60∶40（IV group） and 50∶50（V group）. The results showed that with the extension of fermentation time，the total gas production in each group increased gradually. The growth rate of gas production in group I was the highest，especially at 48 h（GP_{48 h}） which wassignificantly higher than other groups ex- cept the Ⅱ group（P＜0. 05）. With the extension of fermentation time，dry matter digestibility（DMD） and acid deter- gent fiber digestibility（ADFD）increased. DMD_{48 h} and ADFD_{48 h} in group V was significantly lower than that in other groups（P＜0. 05）. The neutral detergent fiber degradability（NDFD_{48 h}） and ADFD_48h increased first and then de- creased with the increase of stevia proportion. NDFD_{48 h} in groups I and II was significantly higher than those in other groups（P＜0. 05）. As the adding stevia increasing，the silage pH reduced ranging from 6. 52 to 7. 18，which was nega- tively correlated with fermentation time. The concentration of ammonia nitrogen（NH₃-N） was between 10. 51 mg/dL and 17. 81 mg/dL，but within the normal range of microorganisms growth. The acetic acid and butyric acid content in mixed silages of different treatments differed significantly （P＞0. 05）. Comprehensive grey correlation analysis showed that the order of mixed silage of stevia and corn straw with different proportions was I Group＞III Group＞II Group＞IV Group＞CK Group＞V Group. Above all，the ratio of corn stalk and stevia stalk at 90∶10，the fermentation effect was the best.