## 4 Discussion  
This study evaluated the efficacy of DPI on the fermentation and aerobic stability of corn silage with different scales of silos. The inoculant consisted of two silage isolates, _L. plantarum_ LP1028 and _L. buchneri_ LBC1029, making it more adaptable to the field environment. DPI silage tended to have a lower LA-AA ratio, indicating more heterolactic fermentation, but no significant differences in nutrient composition was observed during the experiments. Heterolactic fermentation products, such as acetic acid, may inhibit spoilage microbial growth and therefore improve feed-out stability in silage. All silages had pH values less than 4.00, indicating adequate fermentation after conservation; however, the pH value seemed to be higher in DPI silage. This finding is common in previous studies, showing that _L. buchneri_-treated silages are often 0.1-0.2 pH units higher than the untreated silages [13; 28; 29]. Regarding the acid profiles in our results, the LA-AA ratio tended to be lower in DPI silage. As the pH value is dependent on the silage acid profile, it is likely that the pH may rise when lactic acid (pKa of 3.86) is converted to acetic acid (pKa of 4.75) by _L. buchneri_[29; 30]. Heterofementation has been linked to DM losses in silage production [4]. Although DPI contains heteroferminative LAB, previous studies showed that using DPI did not affect the nutritive value in silage [21]. In agreement with the previous findings, our results demonstrated no significant difference in DM when silages were inoculated in all trials. In addition, the control and DPI silages did not differ from each other in terms of CP, ADF, NDF, WSC, starch, and ammonia nitrogen after prolonged storage in all trials. [PERSON] and [PERSON] [31] found that the unfavorable characteristics of _L. buchneri_ may be overthrown in the presence of homolactic inoculant since each type of inoculant can target different aspects of fermentation [31]. _L. buchneri_ is well known for its ability to produce acetic acid and propylene glycol, which inhibit yeast and mold growth [30]. Measurement of propylene glycol can be broadly used to determine whether inoculated _L. buchneri_ dominates fermentation [29]. The ability of _L. buchneri_ inoculant to increase the propylene glycol concentration in silage was not observed in this study except in 45 d laboratory minisilos (_p_ = 0.04), probably because _Lactobacillus diolivorans_, a natural epiphytic bacterium on corn plants, can metabolize this compound to propionic acid and propanol [32]. Acetic acid is the second-highest acid in corn silage, the amount of which affects the aerobic stability of silage [29]. Based on the laboratory-silo results (Table 1), the LA-AA ratio was significantly lower at 45 d DPI (_p_ = 0.014), and a nonsignificant decrease in the LA-AA ratio was also found at 105 d DPI. Figure 5: Thermogram of corn silage after 105-d storage. Corn silage was treated without (left-half) and with (right-half) DPI and the silo working face was exposed to air for 96 h. Color indicated different temperature from low (blue, 27.7 \({}^{\circ}\)C) to high temperature (red, 33.2 \({}^{\circ}\)C). After silo opening, the lower pH (Figure 1b) and YMC (Figure 1a) in DPI further indicated that the onset of aerobic deterioration was delayed by inoculation. Similar results were observed in bunker silage, showing that the pH (Figure 3a) and lactic acid level (Figure 3b) changed more rapidly in the control under aerobic conditions, which may be attributed to lactate-assimilating microorganisms using lactic acid as an energy source and causing a pH increase when the silage is exposed to air [30]. Aerobic stability was not significantly different when this parameter was defined as the hours required for increasing the silage temperature to 2 \({}^{\circ}\)C above the ambient temperature; however, there was a tendency that applying DPI may double the aerobic stability time in the bunker silo after ensiling for 105 days. [PERSON] et al.