## 4 Discussion  
### Effect of Different Growth Stages on Nutritional Components of Whole-Plant Millet Silage  
The degree of maturity at harvest significantly influences the yield, nutritional content, digestibility, and ensling potential of crops [16]. As the growth stage advances, changes in some nutritional values of silage are mostly associated with the degree of seed development and vary according to the different types and varieties of forage crops. Among these, the DM content is a crucial factor affecting silage quality. In this experiment, as the growth stage progressed, the DM content in all treatment groups gradually increased. [PERSON] et al. studied the effects of the pre-heading, heading, and milk stages on the quality of millet silage and found that the DM content increased with the maturity of the millet, which is consistent with our findings [17]. By the time of full maturity, the DM content reached about 40%, as the water content in the plants decreased and sugars in the seeds were converted into starch, thereby increasing the DM content in the seed portion and consequently the whole plant [18; 19]. A high DM content can complicate the compaction process during ensiling, leaving more air, which promotes the growth of yeasts and holds, thereby increasing the risk of \"secondary fermentation\" during feeding. Conversely, a low DM content, indicative of high moisture, can lead to excessive propagation of clostridia, which convert lactic acid into butyric acid, degrading silage quality. This process also triggers effluent loss, resulting in the depletion of WSCs and proteins and ultimately reducing intake by livestock such as cattle and sheep. [PERSON] et al. studied millet at the vegetative and heading stages and found that the cell wall components of the plant significantly increased with the extended growth period. The maximum values for NDF, ADF, cellulose, and lignin were found in the stems, followed by the whole plant and then the leaves. In contrast, hemicellulose, cutin, and silica content were higher in the leaves of the plant [9]. Additionally, [PERSON] et al. studied oat silage  
Figure 3: Relationship between bacterial communities in whole-plant millet silage. (**a**) Phylum level, (**b**) genus level. Note: pos: positive impact; neg: negative impact. at different growth stages and showed that the NDF content increases as the growth stage advances [20]. This difference may be attributed to the varying proportions of stems, leaves, and grains in different varieties, with the ADF and NDF contents being lower in leaves and grains compared to stems [21]. In this study, during the maturation process of forage millet, the NDF content tends to decrease. It is highest at the heading stage, remains relatively stable during the milk and dough stages, and significantly decreases by the mature stage. This trend may be due to the continuous deposition of starch in the grains during the filling process, which leads to a relative decrease in the cellulose content. As the whole-plant millet matures, the CP content initially decreases until the filling stage, then increases, with the CP content at the dough stage being significantly higher than at the filling and milk stages. [PERSON] et al. found that the CP content decreases as the growth stage progresses, which is consistent with our results, which showed a decline in the CP content from the heading to the milk ripening stages [22]. This pattern is echoed in studies by [PERSON] [23], which observed a continuous accumulation of CP in whole-plant millet silage from the pre-milk to dough stages. [PERSON] [24] suggests that an increase in starch content within the silage reduces the proportions of both NDF and CP in the whole plant, explaining why the NDF and CP contents are lower during and after the dough stage compared to the heading stage. However, [PERSON] reports a gradual decrease in CP content from the filling to the dough stage, which may be attributed to varietal differences.