Silage Additives Usage in Improving Fermentation Quality of Alfalfa Silage: A Review

Abstract

Alfalfa is difficult to ensile due to its high protein content, low water-soluble carbohydrate level, low dry matter content, and high buffering capacity. Therefore, alfalfa has recently increased its efforts to make silage with additives. Silage additives have been used to enhancing the silage quality of alfalfa in recent years. This review covers research studies that have investigated the efficacy of silage additives on fermentation quality, the bacterial diversity of alfalfa silage using the Next-Generation Sequencing (NGS) technique, the effects of microbial inoculant on these bacterial communities, silage's antioxidant enzymes, and unsaturated fatty acid levels. In recent studies, more clear information about bacterial communities in silage fermentation has begun to be obtained with the use of NGS technique. In studies using these techniques, it was reported that lactic acid bacteria (LAB) organic acid additions to alfalfa silage caused Lactobacillus, Pediococcus and Sporolactobacillus species to increase relatively in silage environment, the ratio of unwanted species decreased and silage quality increased. Although the amount of alpha-tocopherol, and beta carotene decreased by half in pure silage compared to fresh alfalfa, it was observed that LAB inoculation increased the ratio of alpha tocopherol, beta carotene and also polyunsaturated fatty acids. Future silage additives are expected to determine effects fermentation quality, the bacterial community, the antioxidant enzymes, and unsaturated fatty acid levels.