青贮饲料是一类饲料，多由青绿作物或副产物经过密封、发酵后而成，主要用于喂养反刍动物。青贮饲料比新鲜饲料耐储存，营养成分强于干饲料。另外，青贮饲料储存占地少，没有火灾问题。

青贮饲料经过压实密封，内部缺乏氧气。乳酸菌发酵分解糖类后，产生的二氧化碳进一步排除空气，分泌的乳酸使得饲料呈弱酸性（pH值3.5-4.2）能有效地抑制其他微生物生长。最后，乳酸菌也被自身产生的乳酸抑制，发酵过程停止，饲料进入稳定储藏。但此时原料中的糖分等营养成分损失还不大。

Silage is fermented, high-moisture stored fodder which can be fed to cattle, sheep and other such ruminants (cud-chewing animals) or used as a biofuel feedstock for anaerobic digesters. It is fermented and stored in a process called ensilage, ensiling or silaging, and is usually made from grass crops, including maize, sorghum or other cereals, using the entire green plant (not just the grain). Silage can be made from many field crops, and special terms may be used depending on type (oatlage for oats, haylage for alfalfa – but see below for the different British use of the term haylage).