Effects of chemical additives on the fermentation quality and N distribution of alfalfa silage in south of China

In order to better utilize the last cut alfalfa harvested before killing frost in a high moisture environment, the effects of chemical additives on the quality of alfalfa silage were studied in south of China. The alfalfa was freshly harvested at branching stage, and wilted by dry matter content of about 300 g/kg (fresh matter basis). Silage was prepared by using a small-scale silage fermentation system, where sucrose, potassium citrate, sodium carbonate, formic acid, acetic acid and propionic acid were used as silage additives, and no additives served as control. These silos were stored at ambient temperature (5-20°C), and the silage qualities were analyzed after 120 days of fermentation. All additive treatments affected the chemical composition and N distribution, increased the water-soluble content and crude protein contents, decreased non-protein nitrogen (NPN) content, and enhanced the in vitro ruminal dry matter digestibility (except for sodium carbonate). Silages treated with organic acids were preserved with significantly (P < 0.05) lower pH value, ethanol content and NPN content compared with control. When the fermentation quality, chemical composition and N distribution were considered, the treatment with sucrose or organic acids resulted in high quality of alfalfa silage ensiled before killing frost, with formic acid having the best effect.