Effects of mixed fermentation on the quality of silage

To explore the effect of mixing three types of forage grass with different mass percentages on silage quality, a single-factor complete random design was adopted. The seven treatments were as follows: oat (Avena sativa), corn silage (Zea mays), and soybean (Glycine max) straw-mixed silage (90 ꞉ 0 ꞉ 10 (Ⅰ), 72 ꞉ 18 ꞉ 10 (Ⅱ), 54 ꞉ 36 ꞉ 10 (Ⅲ), 45 ꞉ 45 ꞉ 10 (Ⅳ), 36 ꞉ 54 ꞉ 10 (Ⅴ), 18 ꞉ 72 ꞉ 10 (Ⅵ), and 0 ꞉ 90 ꞉ 10 (Ⅶ), with 3 repeats for each treatment. Three kinds of forage grass were ground into 1～2 cm pieces, air-dried until the water content was between 65% and 70%, and mixed evenly. Wrapped silage was prepared using a silage-wrapping machine with a compactness of 600 kg·m⁻³, and a single package weight of 55 kg, wrapped in five layers, placed in a cool and dry place, and sampled after 45 days. The results showed that with an increase in the proportion of corn silage, aroma of the silage became stronger, structure of stems and leaves became complete, and color changed from light brown to yellowish green. With an increase in the proportion of corn silage in the mixed ratio of oat and corn silage (fresh weight), the contents of butyric acid and acetic acid also decreased gradually, with the content of butyric acid decreasing from 0.89% during treatment Ⅰ to 0.32% during treatment Ⅶ. There was a significant difference among treatments (P < 0.01). The acetic acid content decreased from 5.21% in treatment Ⅰ to 3.07% in treatment Ⅶ (P < 0.01). In terms of nutritional quality, the dry matter (DM) content in treatment Ⅰ was the highest, reaching 34.60% (which was not significantly different from that in treatment Ⅱ), whereas there was a significant difference between treatments Ⅰ and the other treatments (P < 0.01). The content of crude protein (CP) in treatment Ⅰ was the highest, reaching 7.62%, which was significantly different to that of the other treatments. The content of neutral detergent fiber (NDF) in treatment Ⅵ and Ⅶ was approximately 52%, which was significantly lower than that in other treatment groups (P < 0.01). The acid detergent fiber (ADF) content in treatments Ⅴ, Ⅵ, and Ⅶ was approximately 29%, which was significantly lower than that in the other treatment groups (P < 0.01). The water-soluble carbohydrate (WSC) content in treatment Ⅶ was significantly higher than that in the other treatment groups (P < 0.01). Overall, the fermentation and nutritional qualities of oat: corn silage: soybean straw mixed silage at 36 ꞉ 54 ꞉ 10 in treatment V were the highest, whereas the DM, CP, NDF, ADF, and WSC contents were 33.30%, 6.65%, 53.48%, 29.73%, and 2.71%, respectively.