# Quality of Maize Silage After Using Meat Bone Meal as a Phosphorus Fertilizer in a Field Experiment
## 4 Discussion
### Fermentation Parameters and Feed Value of Maize Silage  
Fermentation parameters are important predictors of maize silage quality because acidity and the concentrations of VFAs and N-NH\({}_{3}\) affect feed intake and palatability [43]. The value of pH is one of the key quality attributes of maize silage, and it was high in the present experiment, compared with that reported by [PERSON] et al. [44] (3.7-4.0). Silage acidity is influenced by many factors, mainly LA concentration and the buffering capacity of the ensiled crop. A lower pH of maize silage, relative to that determined in this study, was also obtained by [PERSON] et al. [5] (3.9) and [PERSON] et al. [1] (4.01). Above-normal pH levels in silage may be due to too high buffering capacity, which is generally observed in legumes rather than in maize, and limited fermentation due to e.g., low ambient temperature [44]. Typical LA concentrations in commonly fed maize silages range from 30 to 60 g\(\cdot\)kg\({}^{-1}\) DM [44]; the value noted in this experiment was, on average, twice higher. A wider range of values was reported by [PERSON] et al. [1], 36.7 to 72.1 g LA\(\cdot\)kg\({}^{-1}\) DM. According to [PERSON] et al. [44], the highest LA concentration in maize silage can be achieved with a DM of 351-400 g\(\cdot\)kg\({}^{-1}\), which was not confirmed in this study. Above-average LA concentration in maize silage can be attributed to the composition of epiphytic microbiota and the levels of water-soluble carbohydrates (WSCs) that provide sufficient amounts of substrate for LA bacteria [45]. The composition of epiphytic bacterial communities, the abundance of heteroferenterative genera in the community, and the extent of the transition from hetero-fermentation to homo-fermentation in the initial stage of the ensiling process are important determinants of silage quality [46], and they could affect silage fermentation in the present experiment. Acetic acid is the second most abundant acid in silage [45], and its recommended range for silage made from whole maize plants is 10 to 30 g\(\cdot\)kg\({}^{-1}\) DM [44], which was also observed in this experiment. The AA content of silage, determined in the present study, is adequate and sufficient to inhibit yeast growth. Such a concentration of AA also contributes to improving the aerobic stability of silage [47]. High-quality silage is characterized by a low concentration (<0.1% DM) or absence of PA, which was also observed in the experimental silage. A low proportion of PA in silage is indicative of the absence of activity of _Clostridium propionicum_ bacteria [44]. Well-fermented silage should not contain BA. The presence of this acid is associated with the metabolic activity of _Clostridium_ bacteria, which leads to considerable DM lossesand poor energy recovery [48]. Unfortunately, BA was detected in the silage produced in this experiment. According to [PERSON] and [PERSON] [49], silages containing BA have lower than normal LA concentrations, higher than normal pH, and higher than normal concentrations of AA and N-NH\({}_{3}\), which was not observed in the current study. Increased pH may be due to the activity of _Clostridium_ spp., and the noted concentration of N-NH\({}_{3}\) was below the recommended values (50-70 g\(\cdot\)kg\({}^{-1}\) Ntotal) [44]. The concentrations of AA and N-NH\({}_{3}\) are the most important indicators of maize silage quality. In this experiment, they were consistent with the recommended values, or lower. The LA/AA ratio is commonly used as a qualitative indicator of fermentation. In well-fermented silages, this ratio ranges from 2.5 to 3.0 [44]. In the silages made in this experiment, the LA/AA ratio was above 3.22 and up to 3.93, due to the high abundance of homolactic acid bacteria that produce only LA [45]. In general, the quality of silages with a higher LA/AA ratio should not be considered as low.