## 4 Discussion
### Effect of Moisture Content and Additives on the Fermentation Quality of AWB Mixed Silage
Effect of Moisture Content and Additives on Chemical Composition and In Vitro Digestibility of AWB Mixed Silage  
A suitable MC can protect proteins by reducing the protease activity of the silage material itself. In this study, the AWB mixed silage in the 60% MC group had the highest DM and CP content among the three MC groups. Moreover, the NDF, ADF, and ADL contents in AWB mixed silage gradually increased with increasing MC, indicating that a low MC could better preserve the nutrient content in AWB mixed silage. This was explained by the fact that the increase in DM in the silage reduced the leaching of nutrient solutions by appropriately lowering the MC in the raw material, thus reducing the consumption of nutrients in the silage by microorganisms. Under 60% MC conditions, fewer nutrients were lost from the silage material, and the nutrients in the AWB mixed silage were preserved better than those in the other two MC groups, which had high DM content and did not reach the state of physiological drought. A high MC will promote the growth of harmful microorganisms, such as clostridia and molds, and the exudate produced will carry nutrients out and affect the quality of silage. [PERSON] et al. [25] showed that a low MC treatment could increase the DM level of Sudan grass silage and improve the quality of silage. [PERSON] et al. [26] performed silage on _Lolium multiform_ with different MCs (85%, 75%, and 65%) and found better results at 65% MC, which concentrated nutrients in the silage, inhibited _Clostridium_ and protease activity, reduced NDF and ADF content, and increased DM and CP content compared to 75% and 85% MC, in agreement with the results of this study. In this study, the highest IVDMD and IVCPD were found for the AWB mixed silage in the 60% MC group. This may be because a proper reduction in MC reduced the loss of DM from silage, better preserved the CP and residual WSC content in silage, and utilized more fermentation substrate during rumen fermentation, thus exhibiting a higher IVDMD and IVCPD. Changes in the protein content in silage are not only related to the activity of harmful microorganisms such as clostridia and molds but are also influenced by the protein hydrolytic enzymes contained in plants [40]. [PERSON] et al. [30] showed that when making maize silage, CP and DM were higher and fungal counts were lower in a lactic acid bacteria treatment group than in the control group, indicating that the addition of lactic acid bacteria preserved the nutrient content of the silage and reduced the accumulation of mycotoxins, in agreement with the results of this study for the trials with the addition of L under each MC condition. The WSC content in the two silage feedstocks in this study was high, and the lactic acid bacteria used WSC for growth and reproduction, producing a large amount of LA, and thus creating an acidic environment that increased the inhibition of protease activity and reduced the decomposition of CP. For example, another study found that inoculation of alfalfa silage with lactic acid bacteria preparations increased the CP content and effectively reduced _Bacillus Escherichia coli_ populations [41]. Cellulases, mainly consisting of endo-\(\beta\)-glucanase, exo-\(\beta\)-glucanase, and \(\beta\)-glucosidase, are capable of disrupting the cellulose crystal structure at the nonreducing end of the fiber molecule and releasing simple sugars [42]. The NDF and ADF contents are key indicators to evaluate the quality of silage: when the NDF and ADF contents are approximately low, the silage forage value is approximately high. At 60% MC, the E and M groups had reduced contents of NDF, ADF, and ADL, increased CP content, and an improved nutritional value of AWB mixed silage compared to the control group. AN/TN can reflect the degree of protein degradation in the silage. Under 60% MC conditions, AN/TN was lower in the E and M groups than in the control group. Lower AN/TN also proved that E and M have a good preservation effect on the protein in AWB mixed silage. [PERSON] et al.