Abstract: To evaluate the potential of tannic acid with or without lactic acid bacteria on alfalfa (Medicago sativa L.) silage quality and ruminal fermentation in vitro, alfalfa at the flowering stage was used as the ensiling material, and was air-dried to a moisture content about 55%. Alfalfa was prepared with four treatments, including no additives (CK), tannic acid (TC), lactic acid bacteria (L) and tannic acid + lactic acid bacteria (TL). The silage samples were obtained after 60 days of ensiling, which were subsequently analyzed for the related indexes of fermentation quality and rumen fermentation characteristics in vitro. The results showed that all additive treatments reduced (P<0.05) the pH value and the content of acetic acid and non-protein nitrogen, while dry matter and true protein content of alfalfa silage was increased significantly (P<0.05). The additive treatments can enhance propionic acid production and microbial protein synthesis in the rumen(P<0.05). In conclusion, the combined addition of tannic acid and lactic acid bacteria has the best effect on modulating alfalfa silage fermentation quality and rumen fermentation in vitro.

Key words: Alfalfa, Tannic acid, Lactic acid bacteria, Ensiling, Rumen fermentation

摘要： 为评价单宁酸和乳酸菌单独以及组合添加对紫花苜蓿（Medicago sativa L.）青贮品质和体外瘤胃发酵的影响，本试验以晾晒至含水量约为55%的初花期紫花苜蓿为青贮原料，设无添加剂为对照组（CK），单宁酸（Tannic acid，TC）、乳酸菌（Lactic acid bacteria，L）和单宁酸+乳酸菌（Tannic acid+Lactic acid bacteria，TL）为添加剂处理组。青贮60 d后开袋取样，测定相关指标。结果表明：添加剂处理组均显著降低了青贮饲料的pH值、乙酸和非蛋白氮含量（P<0.05），干物质和真蛋白含量显著增加（P<0.05）；添加剂处理组均能促进瘤胃丙酸生成，提高微生物蛋白产量（P<0.05）；与TC处理组相比，TL处理组能够减轻TC处理组对青贮饲料干物质降解的抑制作用。综上，单宁酸和乳酸菌组合添加对紫花苜蓿青贮饲料品质的调控作用效果最好。

关键词: 紫花苜蓿, 单宁酸, 乳酸菌, 青贮, 瘤胃发酵