## 4 Discussion
In this study, the CP contents slightly decreased at 30 or 40 \({}^{\circ}\)C. The NH\({}_{3}\)-N contents also increased at higher temperature, but the change was extremely small. Nevertheless, regardless of the storage temperature, all LAB-treated sorghum silages had lower NH\({}_{3}\)-N contents than the control silages, which is in agreement with the results reported by [PERSON] et al. [32; 35]. This finding might have been obtained because the selected strains do not ferment amino acids and because protein breakdown was reduced due to a rapid decrease in pH [36]. The inoculants performed good in reducing the fresh weight losses of silage but did not reduce the DM losses. This might be due to the higher loss of volatile products caused by the oven drying, which could also explain the higher ash contents in the inoculant-treated silages [37]. The high temperature of 40 \({}^{\circ}\)C did not cause significantly higher DM losses in this study. However, the silages stored at high temperature still had higher ADL contents. Thus, we tentatively conclude that the high temperature promoted the Maillard reaction, which increased the Maillard polymer contents in the sorghum silage [38]. The inoculants tended to reduce the aNDF and hemicellulose contents of sorghum silage at 20 and 30 \({}^{\circ}\)C. This result confirmed the positive effect of the inoculants on fiber degradation. The LAB-treated silages had lower aNDF contents at 30 \({}^{\circ}\)C, but no significant difference was detected at 40 \({}^{\circ}\)C. A similar phenomenon observed by [PERSON] et al. [39], who inoculated corn stalk silages with FAE-producing LAB and stored the samples at different temperatures. These researchers also found that FAE-producing LAB promoted the degradation of lignocellulosic biomass at lower temperature, but the effect in the absence of cellulase was extremely small [39]. The NDFD of the LP23 group was significantly higher than that of the LF18 group at 30 and 40 \({}^{\circ}\)C, which exactly corresponded to the FAE enzymatic activity of the two LAB strains at the same temperatures, and this finding indicates that FAE might potentially improve the NDFD of sorghum silage. However, it should be noted that the anaerobic and acidic conditions might lead to a different FAE enzymatic activity than that found in the broth. The activity of the FAE produced by the inoculants might be inhibited in an actual ensiling environment [17]. Furthermore, small molecule ferulic acid esters (such as methyl or ethyl ferulate) are usually used in screening for enzyme activity. But these substrates are different from the actual plant ferulate, so we also would like to point out that other characteristic substrates may be able to better predict their effect in silage, which is what we plan to investigate in the future. No significant difference in NDFD was found between the control and LAB-treated silages, which might be due to the epiphytic bacteria in the control group also exhibiting better NDFD-enhancing characteristics than LF18. In the study conducted by [PERSON] et al. [40; 41], the improvement in NDFD was found to be more dependent on other characteristics of the inoculants rather than the expression of FAE. However, due to the potential of FAE to improve digestibility, it may be possible in the future to screen for more effective FAE-producing LAB to degrade the fiber and improve digestibility of silage using the more appropriate methods we mentioned above. Furthermore, cell wall digestibility depends on multiple factors, and further research is needed to explore the potential interactions between FAE-producing LAB and NDFD. The FAE enzymatic activity was low at 20 \({}^{\circ}\)C; thus, no significant difference in the phenolic acid extraction yields was found among the three groups. A higher phenolic acid extraction yield was obtained with LP23-treated silage than with the control and LF18-treated groups at 30 \({}^{\circ}\)C, which corresponded to the enzymatic activity data.