Abstract: During the process of silage, the anaerobic environment can not be completely achieved by fermentation of silage raw materials alone, which not only results in the increase of pH value and ammonia nitrogen content as well as the decrease of lactic acid content in silage, but also may lead to the fermentation of undesirable microorganisms, affecting the effect of silage. To reduce the loss of nutrients during the fermentation process of silage and to improve the fermentation quality and nutritional value of silage, additives are commonly used in silage preparation. The frequently used additives for silage mainly include the following four types: bacterial inoculants, enzyme preparations, fermentation inhibitors and non-protein nitrogen. Different types of additives improve the fermentation quality of silage through varied ways, further ameliorating the nutritional value and feeding effect of silage. This paper reviewed the research progress on the impacts of different types of additives on sensory quality, fermentation quality and microbial diversity of silage, in hoping to provide a reference for the scientific selection of silage additives.

Key words: silage, fermentation quality, bacterial inoculant, enzyme preparation, fermentation inhibitor, non-protein nitrogen