**3.3 Quality evaluation of the silage**

The standardization and development of silage quality grading may help to accurately assess the quality, which is one of the key measures to improve the quality of forage. Generally speaking, quality evaluation of silage includes sensory evaluation and chemical analysis [25]. Sensory evaluation is simple and feasible, but subjective; laboratory evaluation of chemical analysis involves many indicators, which can be quantitatively compared objectivity. According to the color, odor, texture, structure, and other indicators of silage, the quality of silage was evaluated by sensory operation. Chemical analysis evaluation is to quantitatively evaluate the chemical composition of silage through instrumental analysis, while the main indicators are pH value, organic acids (lactic acid, acetic acid, butyric acid, etc.), ammonia nitrogen, total nitrogen, alcohols, and other fermentation parameters.
