中科2号紫花苜蓿青贮过程中长链脂肪酸的变化

Study on the Dynamic Changes of Long-chain Fatty Acids in Medicago sativa‘Zhongke No.2’during Ensiling

以中科2号紫花苜蓿为原料,采用小型袋装青贮法进行青贮,研究青贮前后的营养成分变化,并测定了棕榈酸、棕榈油酸、硬脂酸、油酸、亚油酸和亚麻酸等长链脂肪酸的含量,探究添加乙酸和乳酸菌对青贮长链脂肪酸的影响。结果显示,苜蓿直接青贮品质不佳,添加乳酸菌对苜蓿青贮饲料品质改善作用较小,添加乙酸可以显著降低苜蓿青贮饲料pH值、丁酸含量和氨态氮占总氮比值(P<0.05),同时显著增加乳酸含量(P<0.05),并最大限度保存苜蓿原料草营养成分;苜蓿青贮后棕榈酸含量显著提高(P<0.05);添加乙酸的苜蓿青贮饲料棕榈油酸、油酸、亚油酸和亚麻酸含量显著高于直接青贮(P<0.05),添加乳酸菌的苜蓿青贮饲料油酸、亚油酸和亚麻酸含量显著低于直接青贮(P<0.05),表明添加乙酸和乳酸菌会改变六种长链脂肪酸的动态变化过程。综上所述,苜蓿青贮中添加乙酸可提高总长链脂肪酸含量,有效改善青贮饲料品质。

In this experiment,Zhongke No.2 alfalfa was ensiling by small bag silage method.The changes of nutrients and long-chain fatty acids,including palmitic acid,palmitoleic acid,stearic acid,oleic acid,linoleic acid and linolenic acid,before and after silage were studied,and the effects of acetic acid and lactic acid bacteria on silage long-chain fatty acids were studied.The results showed that the quality of alfalfa silage without any additives was poor,and lactic acid bacteria had little effect on improve its quality.However,acetic acid could significantly decrease pH value,butyric acid content and ammonia nitrogen to total nitrogen,and significantly increased lactic acid content of silage(P<0.05),and preserved the most nutrients of raw alfalfa than others.The content of palmitic acid significantly increased after silage(P<0.05).The contents of palmitic acid,oleic acid,linoleic acid and linolenic acid in alfalfa silage treated with acetic acid were significantly higher than those in no additive silage(P<0.05),while the contents of oleic acid,linoleic acid and linolenic acid in alfalfa silage with lactic acid bacteria were significantly lower than those in no additive silage(P<0.05),which indicated that the dynamic changes of six kings of long-chain fatty acids were changed by adding acetic acid and lactic acid bacteria during alfalfa ensiling.In conclusion,adding acetic acid to alfalfa silage can increase the content of total chain fatty acids and effectively improved the quality of alfalfa silage.