## 4 Discussion
### Effects of KF and LP on Microbial Community  
The application of high-throughput sequencing provided a detailed picture of the microbial community. The Ace and Chao1 indexes were used to characterize the richness of the bacterial community, and the Shannon and Simpson indexes were used to represent the community diversity. In the present study, the decreased Shannon and Simpson indexes caused by KF, LP, and their combination indicated decreased bacterial diversity. It could be explained by the decreased pH, the inhibited growth of undesirable bacteria and the predominance of _Lactobacillus_ caused by the treatments. Similarly, the Shannon index of high-moisture alfalfa silage treated with a commercial LAB inoculant also decreased after 30 days of ensiling [8]. And the combination of L. acidophilus and LP was found to decrease the Chao1, Ace, and Shannon indexes in the whole-plant corn silages [36]. Little is known about the effectiveness of KF on the ensiling process, including microbial community. Despite that, [PERSON] et al. demonstrated that bacterial diversity sharply decreases after successful fermentation [37]. Therefore, KF, LP, and their combination improved the fermentation of high-moisture forage rape silages, evident by the reduction in microbial diversity. During ensiling, LAB plays a key role in silage fermentation. _Lactobacillus_ is one of the most important LAB, which could ferment WSC to lactic acid, reduce pH and prevent silage spoilage caused by undesirable bacteria [8; 38]. Hence, _Lactobacillus_ is often the dominant genus of high-quality silage. In the untreated forage rape silages, _Lactobacillus_ accounted for only 28.23%, while family _Enterobacteriaceae_, as well as genera _Serratia_ and _Clostridium_sensu_stricto_12, were the most abundant bacteria based on the LefSe analysis. The presence of enterobacteria is undesirable as they may compete with LAB for available sugars [39]. Furthermore, members of _Serratia_ may cause important infections in humans, animals, and insects [40]. Clostridia are also undesirable in silages as many of them ferment carbohydrates and proteins, causing problems such as reduction in feeding value and the production of biogenic amines [39]. Besides, Clostridia in silages impair milk quality, and their occurrence and transmission through the dairy chain always cause the death of animals and humans [41]. Ensiling methods that cause a rapid and sufficient drop in silage pH will help to prevent the development of enterobacteria and clostridia [10]. In the present study, the rather high pH value (4.84) of naturally ensiled high-moisture forage rape is not sufficient to inhibit enterobacteria and clostridia. _Lactobacillus_ became the predominant bacterium in all the treated silages, especially for silages treated with the combination of KF and LP, where _Lactobacillus_ was the most abundant genera based on the LefSe analysis. The remarkably increased abundance of _Lactobacillus_ caused by KF and LP was in accordance with the decreased pH value and elevated lactic acid content in forage rape silages. In addition, almost no clostridia were found in the treated silages, which was in line with the nearly eliminated butyric acid. It could be speculated that KF and LP might enhance the fermentation quality of high-moisture forage rape by promoting the proliferation of _Lactobacillus_ and inhibiting the proliferation of undesirable bacteria, such as clostridia. Some studies reported that LAB inoculation might reduce the pH value of silage, but the degree of reduction may be insufficient to prevent undesirable bacteria [8; 42]. Under the current experimental condition, the inhibition effect of LP on undesirable bacteria is obvious, which was in line with previous studies conducted with high-moisture alfalfa and Napier grass [18; 31]. So far, no information is available regarding the effect of KF on silage quality or microbial community.