Effects of the addition of grape pomace on the quality and in vitro digestive characteristics of alfalfa silage

This study evaluated the effect of grape pomace on the fermentation quality and in vitro digestibility of alfalfa silage. Experiments were conducted using alfalfa ‘Xinmu No. 4’ (Medicago sativa ‘Xinmu No. 4’) and Cabernet Sauvignon grape pomace as raw materials. A control group (alfalfa silage alone) was analyzed alongside the experimental groups C₁ (with 100 g·kg⁻¹ grape pomace), C₂ (with 150 g·kg⁻¹ grape pomace), and C₃ (with 200 g·kg⁻¹ grape pomace). The fermentation quality, nutrient composition, and in vitro digestibility of each treatment were measured after 60 d of silage. The results showed that the addition of grape pomace increased the content of alfalfa silage protein and lactic acid, improved the score of V-Score, reduced the pH and ammonia nitrogen content of alfalfa silage, and increased the in vitro digestibility of alfalfa silage dry matter and crude protein, thus improving the quality of alfalfa silage. The quality of silage was C₂ > C₃ > C₁ > control group. Overall, grape pomace was found to improve the fermentation quality and in vitro digestion of alfalfa silage. With 150 g·kg⁻¹ of grape pomace added to alfalfa for silage being the most effective.