## 4 Discussion  
The contents of WSC and LAB are critical for successful ensilage. Previous studies showed that with a low WSC content, inoculants will not produce enough LA due to the limitations of the substrates, and the presence of sufficient LAB can convert WSCs into LA and lower the pH value in an anaerobic environment [24; 25]. However, previous research also showed that relatively low contents of WSC and LAB were observed in _L. chinensis_[10; 26]. Therefore, in order to promote fermentation, it is necessary to supplement WSC or LAB inoculants. In addition, the _L. chinensis_ stalk is hollow and hard; thus, removing all the air when making silage is difficult [10]. Compacting and chopping were used to exhaust the air from _L. chinensis_ stems to make high-quality _L. chinensis_ silage. In our experiments, SU, LP and SU+LP were added to _L. chinensis_ silage, which was cut into different lengths. The pH value is an important factor that reflects the silage quality, and a pH value below 4.20 is considered an important key indicator for inhibiting the growth of contaminating microorganisms [27]. For processing silage, the key factors that determine the pH value are the LA and AA contents. Lower pH value and higher LA content were obtained in _L. chinensis_ silage with the shorter chopping length, which was consistent with the results of [PERSON] et al. [12]. Additionally, lower pH value and higher LA content were detected with the SU+LP treatment at all lengths. Moreover, the results of ensiling for 30 d and 90 d were similar. Usually, both biological (mainly consisting of homofermentative LAB) and chemical additives are used to improve silage quality [28; 29]. The addition of homofermentative LAB to forage at ensiling can enhance the fermentation process by producing high concentrations of LA and rapidly reducing the pH of the silage [17]. Similar results were found in our experiments. In addition, we found that when the cut length was 4-5 cm, all additives showed positive effects on _L. chinensis_ preservation, and LP or SU+LP treatments resulted in lower pH values and higher LA contents. _Lactobacillus buchneri_ (LB) were reported to increase the AA content, and _L. plantarum_ (i.e., LP in this study) was shown to increase the LA content [23; 30]. In our study, inoculation of the _L. chinensis_ silage with LP increased the AA content and thereby affected the lactate:acetate ratio, which might be related to the lack of effect of inoculation on certain fermentation end products. However, the increased BA content upon the addition of SU with ensiling for 90 d was difficult to explain, and it may have arisen from _Clostridia_ reproduction in the silage [31]. The yeast count of the 4-5 cm length with no additives was \(1\times 10^{3.63}\) cfu/g FM, which was higher than the count in the other treatments. The results showed that the yeast number was inhibited by the length of chopping and additives. The aerobic deterioration of silage is a significant problem for farm profitability and feed quality throughout the world [32; 33]. After the silo was opened, the anaerobic environment became aerobic immediately, and aerobic microorganisms began to reproduce. Generally, the aerobic deterioration of silage is mainly caused by the activities of aerobic microorganisms such as yeast and mold, which use the LA and residual carbohydrates, amino acids and proteins produced by silage fermentation to release heat from the silage and cause the deterioration of aerobic metamorphism [34]. In this study, when the cutting length was 4-5 cm, the yeast and mold levels of _L. chinensis_ silage were higher than those in all the other treatments, and the aerobic stability of _L. chinensis_ silage was poorest with no additives. Molasses and LAB have been reported to promote resistance to aerobic deterioration [35; 36], and similar results were found in this study. When the chopping length was longer, the aerobic stability increased with the addition of SU, LP and SU+LP. In addition, we found that _L.