## 3 Results
### Changes of pH Value and Acidic Substances of L. _chinensis_ Silage  
The dynamic changes in the pH value and LA content during the process of aerobic exposure of _L. chinensis_ silage with different chopping lengths and different additives are given in Figure 3. At 1-2 cm, with no additives, the pH value remained stable after the silo had been opened for 3 d, and it increased 5 d after exposure to air. With the addition of LP, the pH value did not change after the silo had been opened for 5 d, but it increased 7 d after exposure to air (Figure 3A); after exposure to air for 3 d, the LA content of the control silage with no additives and the LP- and SU+LP-treated silage remained stable. With the addition of SU, the LA content decreased from 27.42 g/kg DM to 17.12 g/kg DM. Additionally, the LA content was close to 0 during the 7-d spoilage test for all treatments (Figure 3B). At 4-5 cm, with the addition of LP or SU+LP, the pH value was lower compared to the control and remained stable after the silo had been opened for 5 d and increased 7 d after exposure to air. With the addition of SU or with no additives, the pH value tended to increase after 3 d of exposure to air (Figure 3C); the LA content of _L. chinensis_ silage treated with LP or SU+LP was higher than that of the control or silage treated with SU on 0 to 5 d of aerobic exposure. After aerobic exposure for 7 d, the LA content was close to 0 for all treatments (Figure 3D). \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multicolumn{1}{c}{\multirow{2}{*}{**Treatments**}} & **Aerobic Stability** & **Maximum Temperature** & **Time to Maximum** \\  & **(h)** & **(\({}^{\circ}\)C)** & **Temperature (h)** \\ \hline  & Length & \textless{}0.001 & 0.088 & \textless{}0.001 \\ \hline \(p\)-Value & Additive & \textless{}0.001 & 0.010 & \textless{}0.001 \\ \hline  & Interaction & \textless{}0.001 & 0.825 & \textless{}0.001 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Significant analyzes of length, additive, and their interactions on aerobic stability, maximum temperature and the time to maximum temperature of _L. chinensis_ silage. Figure 3: Dynamic changes in the pH value during aerobic exposure of _L. chinensis_ silage treated with different additives at 1–2 cm length (**A**) and 4–5 cm length (**C**). Dynamic changes in the lactic acid content during aerobic exposure of _L. chinensis_ silage with different additives at 1–2 cm length (**B**) and 4–5 cm length (**D**). SU, sucrose; LP, _Lactobacillus plantarum_; DM, dry matter. The dynamic changes in the acetic acid, propionic acid and butyric acid contents during aerobic exposure of _L. chinensis_ silage with different chopping lengths and different additives are given in Figure 4. At 1-2 cm, the AA content decreased after silo opening during the 7-d spoilage test. After 7 d of aerobic exposure, the AA content of _L. chinensis_ silage treated with LP was 11.72 g/kg DM, which in the other treatments was close to 0 (Figure 4A); the PA content fluctuated from 5 g/kg DM to 15 g/kg DM and decreased after 7 d of aerobic exposure (Figure 4B); after exposure to air for 3 d, BA was detected on all the days with the addition of SU. In contrast, BA was not detected at any number of days of aerobic exposure with the addition of LP (Figure 4C). At 4-5 cm, the AA content of _L. chinensis_ silage treated with LP and SU+LP was higher than that of control and SU at 0 to 7 d after aerobic exposure. After aerobic exposure for 7 d, the AA content was close to 0 for all treatments (Figure 4D); no regular changes of the PA content were detected after the silo had been opened for 7 d (Figure 4E); BA was detected at 7 d of aerobic exposure in the SU and control, but was not detected in LP and SU+LP treatments at 0 to 5 d of aerobic exposure (Figure 4F). Figure 4: Dynamic changes in the acetic acid content during aerobic exposure of _L. chinensis_ silage with different additives at 1–2 cm length (**A**) and 4–5 cm length (**D**). Dynamic changes in the propionic acid content during aerobic exposure of _L.