# The Effect of Meat and Bone Meal on Yield and Herbage Quality in Silage Maize
## 3 Results and Discussion
### Nutritional Value of Maize Herbage  
In this study, the CP content was significantly higher in whole-crop maize herbage provided with mineral fertilizers or MBM than in the zero-fert treatment (Table 3). No significant differences were noted between the inorganic NPK treatment and MBM treatments (\(p>0.05\)). The lowest dose of MBM (1.0 Mg\(\cdot\)ha\({}^{-1}\)) supplemented with mineral N at 50% ensured an adequate supply of N to plants, at the level closest to that in the NPK treatment. In a study by [PERSON] et al. [24], the obtained protein yield of silage maize differed significantly at different doses of MBM; however, an increase in protein yield was not linearly related to increasing MBM doses. In comparison with the NPK fertilizer, which supplied the same amount of N as 2.0 Mg\(\cdot\)ha\({}^{-1}\) MBM, the yield of protein was significantly higher under MBM fertilization than mineral fertilization. The chemical composition of maize plants, particularly the contents of N, P, and K as well as N use efficiency, were affected by weather conditions and the supply of other mineral nutrients [5; 42]. [PERSON] et al. [27] found that soil abundance with mineral plant-available forms of N was significantly influenced by MBM doses and then by weather conditions during the growing seasons and crop species. A comparison of the mean values of the analyzed parameters of maize herbage harvested during three growing seasons revealed significant (\(p\leq 0.05\)) differences (Table 3). In the first year of the study (2014), maize herbage had the highest content of DM, CP, and EE, and the lowest CF concentration. In 2019 and 2020, the herbage was less abundant in DM, CP, and EE, and more abundant in CF, which is consistent with the findings of [PERSON] et al. [43] who found that an increase in the moisture content of plants was accompanied by an increase in fiber concentration. This relationship was also noted in this study where 2019 was characterized by abundant rainfall, nearly two-fold higher than in 2014, whereas weather conditions were optimal in 2020. Water available to plants has a significant effect on their growth and the chemical composition of forage, mostly due to its influence on plant maturity, the leaf blade-to-stem ratio, and the rate of senescence [43]. According to other researchers [44], water deficits induce a decrease in the leaf, stem, cob, and total fresh yields of maize, which was associated with lower nutritional value of maize grown for fodder. The content of nutrients, particularly CP, is one of the key parameters of biomass quality in fodder crops intended for silage production. In the current experiment for the CP content, an interaction was found between maize fertilization and the year of the study (Table 3, Figure 1). The response of plants to fertilization in particular years varied in terms of protein content. The closest CP content was recorded in 2014. According to the literature, the N rate exerts a significant effect on the CP content of maize plants, whereas its influence on the composition and concentrations of structural carbohydrates is ambiguous. The effect of N fertilization on the CP content of plant fractions may be determined by the availability of irrigation water [45]. [PERSON] et al. [46] demonstrated that water availability and N fertilization act synergistically, but there is no clear information on the combined effect exerted by both factors on maize yield, plant fractions, and chemical composition. In the present study, an interaction was observed  
Figure 1: Interaction between fertilization and year of study for the crude protein (CP) content of maize herbage; a, b, c within a year (\(p\leq 0.05\)). between the experimental factors for DM content (Figure 2). The high maize herbage yield achieved in 2019 resulted from a decrease in DM content in three treatments, whereas in the other two treatments (zero-fert and 1.5 Mg MBM), the DM content decreased only slightly relative to that in 2014.