Abstract: In order to study the effects of three different additives on the silage quality of alfalfas, the second cut Algongum alfalfa with 70% moisture content were ensiled with addding Radix astragalus (0, 5, 10 g·kg^-1), formic acid(0, 6 mL·kg^-1), sucrose (0, 20 g·kg^-1), respectively. At the end of ensiling period (45 days), the silages were sampled and the fermentation quality, chemical composition and LAB counts were analyzed. Results showed that the pH values of silages were significantly lower in all additive treatments (5 g·kg^-1 Radix astragalus except) in comparison with control (P<0.01). Lactic acid contents and lactic acid/acetic acid ratios showed significantly higher than control (P<0.05). NH₃-N/total N ratios in all additive treatments (except sucrose) were significantly decreased (P<0.05). The effect of formic acid on NH₃-N/total N ratios was better than Radix astragalus. However, formic acid had a certain corrosive. Lactic acid bacteria were significantly increased in 10 g·kg^-1 Radix astragalus treatment (P<0.05). From a safety point of view and silage quality considerations, the 10 g·kg^-1 of Radix astragalus was recommended as silage additives.

Key words: Alfalfa, Radix astragalus, Silage quality, Formic acid, Sucrose

摘要： 为研究不同添加剂对紫花苜蓿(Medicago sativa L.)青贮效果的影响,以第2茬70%含水量的阿尔冈金品种为材料,分别设置添加黄芪(0, 5, 10 g·kg^-1)、甲酸(0, 6 mL·kg^-1)、蔗糖(0, 20 g·kg^-1)用对照(未添加)共5个处理组,调制青贮饲料,45 d后开封并取样分析。结果表明:甲酸、蔗糖和10 g·kg^-1黄芪组均极显著降低紫花苜蓿青贮的pH值(P<0.01);蔗糖组显著增加乳酸含量及乳酸/乙酸比(P<0.05);甲酸和2个黄芪组均极显著降低氨态氮/总氮比(P<0.01),其中甲酸效果最好,黄芪次之; 10 g·kg^-1黄芪组显著增加乳酸菌含量(P<0.01)。甲酸具有一定腐蚀性,从安全角度和青贮品质方面考虑,推荐使用10 g·kg^-1的黄芪作为青贮添加剂。

关键词: 紫花苜蓿, 黄芪, 青贮品质, 甲酸, 蔗糖