Silage is the green feed that moisture content is 65%-75% after be being chopped, below the condition of airtight hypoxia, through the ferment action of anaerobic lactobacillus, restrain the reproduction of all sorts of miscellaneous bacteria, and get a kind of rouge feed. Silage is a good source of livestock feed with sour and sweet smell, soft and juicy, good palatability, rich nutrition and good long-term preservation.

　　The selection of silage materials should pay attention to the following matters

　　1. High sugar content of silage raw materials. The content of sugar refers to the content of soluble carbohydrates in silage raw materials, which is the basic condition to ensure the mass reproduction of lactic acid bacteria and the formation of sufficient lactic acid. The sugar content of silage raw materials should be at least 1% ~ 1.5% of fresh weight. The raw material with high carbohydrate content and low protein content should be selected as the raw material for silage. For example: grass plants, sunflower stems and leaves, root tubers raw materials are high carbohydrate species. However, raw materials with less soluble carbohydrates and more protein, such as legumes and potato stems and leaves, are more difficult to be silage successfully and generally not suitable for single silage. Semi-dry silage is usually prepared by cutting these raw materials and pre-drying them until the water content reaches 45-55%.

　　2. Silage materials must contain adequate water. Proper moisture is an important condition for normal microbial activity. Too low water, affect the activity of microorganisms, in addition, it is difficult to compacting, resulting in a large number of good air bacteria reproduction, so that the feed mildewy decay; Excessive water and low sugar concentration are conducive to the activities of tyrosine bacteria, easy to agglomerate, and the quality of silage deteriorates. At the same time, plant cells lose juice and nutrients. To the feed with excessive moisture, should slightly air dry or add dry feed mixture silage. When the water content of silage material is 65-75%, it is the best for lactic acid bacteria to reproduce. The water content of leguminous herbage was 60-70%. The moisture content of rough and hard material is 78-80%. The moisture content of tender, juicy and soft raw materials should be 60%.