# Quality of Maize Silage After Using Meat Bone Meal as a Phosphorus Fertilizer in a Field Experiment
## 4 Discussion
### Chemical Composition of Maize Silage
The maturation of maize plants during grain filling is associated with an increase in DM and starch content, and a decrease in NDF and CP concentrations. These changes occur unevenly in individual parts of the plant, i.e., leaves, cobs, and stems, which is also an important consideration. The NDF content of stems increases with advancing maturity, whereas NDF concentration in the entire crop decreases due to a more rapid increase in the proportion of grains in the DM of whole plants, compared with the NDF content of stems. As a result, a negative relationship (R\({}^{2}\) = 0.669) between starch concentrationand NDF content can be observed in maize silage. Therefore, a deliberate delay in the harvesting process to attain a high starch content of maize silage will result in a reduction in NDF content, particularly digestible NDF content [28; 31]. In a study by [PERSON] et al. [5], a substantial increase in starch concentration and a considerable decrease in NDF content were observed when the DM content of maize silage increased from \(<\)250 g\(\cdot\)kg\({}^{-1}\) FM to 250-290 g\(\cdot\)kg\({}^{-1}\) FM. The processes of ear growth and nutrient accumulation in grains occur rapidly in the early grain-filling stage. However, their rate decreases as the maturation process progresses. Consequently, ensiling maize at an early maturity stage and DM content \(<\)250 g\(\cdot\)kg\({}^{-1}\) FM can be expected to decrease the starch/NDF ratio. Thus, maturity at harvest influences not only the chemical composition of silage, but also its digestibility and fermentation quality [5]. The relationships described above were also observed in this study although all maize plants were harvested in the milk-dough stage in all years of the experiment. Maize harvested in 2019 was characterized by significantly lower DM content and significantly higher NDF content than maize harvested in 2014 and 2020. Maize silage is relatively low in CP, and CP content and digestibility decrease with advancing maturity [5]. [PERSON] et al. [32] found that genetic variation had a significant effect on the concentrations of total CP (62-89 g\(\cdot\)kg\({}^{-1}\) DM) and CP fractions in maize, which is consistent with previous findings [33; 34]. In the work of [PERSON] et al. [35], maize cultivars were characterized by different molecular structures of proteins, which were correlated with protein solubility and rumen degradability. High negative values of the degraded protein balance in the rumen were noted for maize silage, pointing to a high N deficiency in the rumen relative to the amount of degraded energy when maize silage was the sole source of nutrients for dairy cattle [35]. According to [PERSON] et al. [36], whole-crop CP content is significantly influenced by N fertilization. In turn, [PERSON] et al. [37] found that N fertilizer induced an increase in total N content only in some maize cultivars. The CP content of maize increases in response to N fertilization due to the role of N in protein synthesis [36]. In addition, N is the main factor limiting plant growth and development. Soil N availability, as well as weather conditions and agronomic practices, play an important role in maize cultivation. Another important aspect is the CP content of maize leaves, as they are associated with metabolic activity such as photosynthesis and high N concentration [38].