Abstract:

The contents of total saponins in both alfalfa and alfalfa silage were determined by colorimetric method. The results showed that the contents of total saponins in different alfalfa varieties were significantly different (P <0.01), which were the range of 0.69%～0.98%. The contents of total saponins also were significantly different among different harvest phases (P <0.01). The contents of total saponins in all tested developmental stages at the second harvest were higher than that at the first harvest, and there was the highest content of total saponins at budding stage, the highest level was 51.72% more than the lowest level. The content of total saponins in the control was the lowest level which was 0.65%. The content of total saponins in the fresh samples was 1.07% and higher than that of alfalfa silage (P <0.01), which indicated the content of total saponins could be effectively decreased by ensilaging. Therefore, it is an effective method to decrease the content of total saponins by selecting ‘Forerunner’ and ‘Captain’ varieties as the materials of ensilage, which the best harvest phases are early flowering at the first harvest and pod period at the second harvest, and using sucrose and previous fermented juice as the additives of ensilage.

Key words: Alfalfa, Saponins, Colorimetric method, Silage

摘要：

为研究比较不同品种、刈割时期紫花苜蓿(Medicago sativa)总皂苷含量变化及添加剂处理的苜蓿青贮后总皂苷变化的程度,采用比色法对总皂苷含量进行测定。结果表明:不同苜蓿品种间总皂苷含量差异极显著(P <0.01),总皂苷含量范围为0.69%～0.98%。不同刈割时期苜蓿青贮间的皂苷含量差异极显著(P <0.01),第2茬不同生育期比第1茬相应时期皂苷含量都有增加趋势,不同生育期以现蕾期含量最高,苜蓿皂苷含量最高的时期比最低时期要多51.72%。不同添加剂处理的苜蓿青贮以对照组含量最小为0.65%,蔗糖和绿汁发酵液处理的苜蓿青贮皂苷含量之间差异不显著,但与对照组相比差异极显著(P <0.01)。苜蓿鲜样中总皂苷含量最高为1.07%,与苜蓿青贮相比较差异极显著(P <0.01),苜蓿青贮总皂苷含量较青贮前明显降低。选择‘先驱者’、‘首领’2个苜蓿品种,在第1茬初花期、第2茬结荚期进行刈割,以蔗糖和绿汁发酵液作为添加剂制作青贮,可以有效降低总皂苷含量。

关键词: 苜蓿, 皂苷, 比色法, 青贮