Silage quality and in vitro rumen fermentation characteristics of stevia and corn stalks

We evaluated the silage quality and fermentation characteristics of different proportions of stevia stalk and corn stalk. Six treatment combinations with varied ratios of corn stalk and stevia stalk 100 ꞉ 0 (CK), 90 ꞉ 10 (A), 80 ꞉ 20 (B), 70 ꞉ 30 (C), 60 ꞉ 40 (D), and 50 ꞉ 50 (E) were prepared. The materials in each group were mixed, sealed, and fermented for 60 days, after which their silage quality and fermentation characteristics were determined. The sensory quality of silage with different mixing ratios was excellent. The dry matter (DM), Ca, and crude protein (CP) contents were increased after ensilage (except for in the CK group and Ca in group D). Additionally, the monosaccharide (ESC), P, neutral detergent fiber (NDF), and acid detergent fiber (ADF) contents decreased in each group, although NDF and ADF increased with increasing Stevia rebaudiana. After ensilaging, DM, Ca, and CP contents in group C increased by 1.92%, 18.46%, and 42.15%, respectively, compared with those in group CK. The CP content in group D was significantly lower than that in the other groups (P < 0.05). Except for groups A and B, the ADF content in all groups significantly differed from that in the CK group (P < 0.05). The pH of the forage after silage was 3.68～4.14. The ammonia nitrogen/total nitrogen (NH₃-N/TN) level increased as the proportion of stevia stalk increased, except for in group E. The lactic acid content in the CK group was significantly lower than that in the other groups (P < 0.05). In vitro gas production was highest in group A (157.92 mL·g⁻¹). The DMD and NDFD in groups A, B, C, and D were higher, respectively, than that in group E (P < 0.05). The range fermentation pH values was 6.52～6.84, and the NH₃-N concentration in group D was significantly lower than those in the other groups. The content of isobutyric acid and valeric acid in CK group was higher than that in the other groups. These results show that the quality of maize silage can be improved by mixing with corn stalk and stevia stalk in a 90 ꞉ 10 ratio.