###### Abstract  
Two lactic acid bacteria (LAB) strains with different ferulic acid esterase (FAE) activities were isolated: _Lactobacillus fraciminis_ (LF18) and _Lactobacillus plantarum_ (LP23). The effects of these strains on the fermentation quality, in vitro digestibility and phenolic acid extraction yields of sorghum (_Sorghum bicolor_ L.) silage were studied at 20, 30 and 40 \({}^{\circ}\)C. Sorghum was ensiled with no additive (control), LF18 or LP23 for 45 days. At 40 \({}^{\circ}\)C, the lactic acid content decreased, whereas the ammonia nitrogen (NH\({}_{3}\)-N) content significantly increased (\(p<0.05\)). At all three temperatures, the inoculants significantly improved the lactic acid contents and reduced the NH\({}_{3}\)-N contents (\(p<0.05\)). Neither LP23 nor LF18 significantly improved the digestibility of sorghum silages (\(p>0.05\)). The LP23 group exhibited higher phenolic acid extraction yields at 30 \({}^{\circ}\)C (\(p<0.05\)), and the corresponding yields of the LF18 and control groups were improved at 40 \({}^{\circ}\)C (\(p<0.05\)). FAE-producing LABs might partially ameliorate the negative effects of high temperature and improve the fermentation quality of sorghum silage. The screened FAE-producing LABs could be candidate strains for preserving sorghum silage at high temperature, and some further insights into the relationship between FAE-producing LABs and ensiling temperatures were obtained. s 2021 9 114 11.11.  
the cell wall. Microorganisms containing particular ferulic acid esterases (FAEs) can remove side chains attached to the main chains in hemicellulose, and this process makes the polysaccharide backbone accessible to main-chain-degrading enzymes [7]. The free forms of ferulic acids and \(p\)-coumaric acids are released after disruption of their ester bonds by esterases in the plant cell wall, which might have a variety of implications for the livestock diet [6; 8]. The vast majority of feruloyl esterases have been found in fungi (e.g., _Aspergillus niger_, _Penicillium funcitolsum_, _Neurospora crassa_ and _Talaronymces stipitatus_), and different fungi tend to produce diverse types of esterases with a variety of substrate activities [9]. The hydrolysis rate of an esterase from bacteria, such as _Pseudomonas fluorescens_, is significantly lower than that of fungal feruloyl esterases [9]. However, most esterase-producing fungi are strictly aerobic and cannot be grown under ensiling conditions [10]. Moreover, the addition of exogenous feruloyl esterases would increase the silage cost. Therefore, FAE-producing LAB, which can exhibit tolerance to low pH and anaerobic conditions, might play crucial roles as silage inoculants [10]. FAE-producing LAB makes cross-linked polysaccharides more fragile and thus more easily degraded by rumen due to the synergy between esterases and main-chain degrading enzymes [10]. Several research studies have attempted to study the effects of FAE-producing LAB strains on ensiling and fiber degradability, and some of the findings have shown that LAB-treated silage exhibits higher neutral detergent fiber digestibility (NDFD) [11; 12; 13]. The success of silage making might also depend on the ability of the LAB to adapt to hot weather [14]. In general, a moderate temperature of 20-30 \({}^{\circ}\)C is most suitable for silage fermentation [15]. However, sorghum is mostly harvested and ensiled from June to September in China, which is the hottest period of the year. Researchers have reached a consensus that high temperature usually exerts detrimental effects on the ensiling process. High temperature tends to accelerate the aerobic deterioration of silages and thus leads to butyric and alcoholic fermentation [16]. In addition, some early studies have shown that temperature also significantly affects the activity of FAE produced by LAB [10; 17]. Lactic acid bacteria can dominate homolactic or heterolactic fermentation. With the homolactic fermentation, only lactate is produced.