Effect of storage temperature and ensiling period on fermentation quality of high moisture alfalfa silage

To investigate the effect of storage temperature and ensiling period on fermentation quality of high moisture alfalfa (Medicago sativa) silage at 15, 25 and 35 ℃, silage quality and microbial composition were analyzed after ensiling for 14, 28 and 56 days. Storage temperature, ensiling period and their interaction significantly influenced the silage quality and microbial composition (P < 0.05). Silage pH, butyric acid, ammonia nitrogen content and clostridial counts decreased in high moisture alfalfa silage ensiled at 15 ℃ (P < 0.05) compared to 25 and 35 ℃, while lactic acid, crude protein content and dry matter recovery increased (P < 0.05). As the ensiling period continued, lactic acid content significantly increased (P < 0.05) but silage pH decreased in alfalfa silage ensiled at 15 ℃ (P < 0.05). A decrease in lactic acid content was seen in alfalfa silage ensiled at 35 ℃. After 56 days of ensiling, alfalfa silage ensiled at 15 ℃ had the highest content of lactic acid (22.7 g·kg⁻¹) and crude protein (176 g·kg⁻¹) and lowest content of butyric acid (1.86 g·kg⁻¹) and ammonia nitrogen (71.9 g·kg⁻¹). The V-Score of alfalfa silage at 15 ℃ was fair, but it was poor at 25 and 35 ℃. Therefore, after ensiling for 56 days, high moisture alfalfa ensiled at 15 ℃ preserved nutritional value and improved fermentation quality more than ensilage at 25 and 35 ℃.