**3.2 Additives**

In addition to a small amount of LCB in raw materials, there are also a large number of spoilage bacteria, yeasts, and other flora that are not conducive to silage fermentation. Most of these floras are aerobic bacteria, while lactobacilli belong to anaerobic bacteria. In the early stage of fermentation, the LCB begin to propagate only after the oxygen in silage is consumed by these aerobic mold spoilage bacteria to form an anaerobic environment. In this process, silage will cause fever and serious occurrence of earthy or mildew taste, which are all adverse factors from silage. Artificial addition of additives can shorten the process, which makes LCB become the dominant bacteria group of silage and improve the overall quality of silage. At present, there are more than 200 silage additives used all over the world, which can be classified into four categories as a whole, namely, bacterial inoculants, enzyme, non-protein nitrogen, and preservatives.
