## 3 Results and Discussion
### The Fermentation Parameters, Organic Acids and Microbial Population of ML Silages  
DM recovery, the dynamics of the pH value, organic acid content and microbial population counts in ML silages are shown in Figure 1. The factor analysis revealed that CA had a significant effect (\(p<0.01\)) on DM recovery, pH, lactic acid content, acetic acid content, lactic acid bacteria counts and coliform bacteria counts in ML silages. DM loss is a common issue during every stage of ensiling, which reduces the silage yield [24]. The silages treated with CA showed higher DM recovery than the CK, and the highest DM recovery occurred in the silages treated with 2% CA after 30 days of ensiling. The increase in DM recovery would significantly improve the economic efficiency of ML as an excellent protein supplement for livestock. The pH is the most intuitive fermentation parameter, which directly reflects the quality of silage. The pH value of silages treated with CA was lower than that of the CK during the ensiling process in this study. The pH value of ML silages reached stability in 3 days of ensiling, and the final pH was lower than 4.5 with the addition of 2% CA. It might be that enough CA directly reduced the pH value due to its strong acidity, with a pK1 3.13 [10]. However, the pH value of silage treated with 1% CA was maintained at around 5.0 and the final pH value of the CK remained approximately 6.0, which might be due to the high buffer capacity of ML [25]. The relatively low pH of ML silage ensiled with CA indicated that CA could effectively promote the fermentation of ML. During the ensiling process, lactic acid and acetic acid were the dominant organic acids in ML silage, and no butyric acid or propionic acid was detected. The addition of CA significantly increased (\(p<0.01\)) the lactic acid content and reduced the acetic acid content of ML silages. Similarly, [PERSON] et al. [14] reported that 0.1% CA and 0.5% CA increased the lactic acid content. In the first 7 days of ensiling, the lactic acid accumulated rapidly in the ML silages. After 7 days of ensiling, the lactic acid content decreased in the silages treated with 2% CA, and after 14 days of ensiling in the CK and the silages treated with 1% CA. At the same time, the acetic acid content of the CK and the silages treated with 1% CA increased. The drop in lactic acid content and the rise in acetic acid content indicated that part of the lactic acid was converted into acetic acid, which might be caused by hetero-fermentation of the lactic acid bacteria, such as _Lactobacillus buchneri_[26]. Moreover, the ML silages treated with CA showed a lower (\(p<0.01\)) ratio of acetic acid to lactic acid than the CK, which suggested that the addition of CA promoted the accumulation of lactic acid and inhibited the production of acetic acid during the ensiling process. The dynamics of lactic acid bacteria, coliform bacteria and yeasts are shown in Figure 1. In the first 7 days of ensiling, lactic acid bacteria counts increased rapidly, which could explain the accumulation of lactic acid at the same time. The lactic acid bacteria counts then decreased from 8.0 log10 cfu/g FM to 6.0 log10 cfu/g FM when the ensiling time was prolonged, which was consistent with the report by [PERSON] et al. [2]. The reduction in lactic acid bacteria counts might be explained by the lack of water-soluble carbohydrates as a fermentation substrate [27]. Compared with the CK, lower (\(p<0.01\)) coliform bacteria counts were observed in the silages treated with CA during the ensiling process, which could explain the higher DM recovery and the lower acetic acid content in these silages. Moreover, the reduction in coliform bacteria counts of silages treated with CA was consistent with those reported by [PERSON] and [PERSON] [28]. When the ensiling time was prolonged, yeast counts decreased (\(p<0.01\)), which might be because the progressively anoxic situation inhibited its growth. Unexpectedly, no yeast was detected in the silages treated with 2% CA during the fermentation process.