## 3 Results and Discussion
### Concentration of Volatile Fatty Acid (VFA) in Pig Slurry
However, even though the peat moss used in our study had a high fiber content, a 3% inclusion of peat moss had a limited impact on enhancing VFA levels in the pig slurry. The authors of [49] examined factors affecting VFA content in stored pig slurry, encompassing diet, season, storage location, conditions (covered or aerated), and pig operation type (finishing, sow, mixed), with pig operation type emerging as the most prominent factor. In the present study, maintaining consistent conditions except for dietary variations, the utilization of excreted sow slurry enabled the attribution of the observed difference in VFA content between the PFS and CTL mainly to the presence or absence of peat moss supplementation. During the experimental period, the pH of the CTL and PFS ranged from 7.4 to 7.8 and 7.5 to 8.1, respectively. The relationship between VFA accumulation and pH decrease in the pig slurry did not show a clear trend in either group. Changes in CH\({}_{4}\) Carbon (CH\({}_{4}\)-C), CO\({}_{2}\) Carbon (CO\({}_{2}\)-C), and Carbon Dioxide Equivalent (CO\({}_{2}\)-eq.) Emissions during Storage of Pig Shurry  
A comparative analysis of carbon emissions was conducted to determine the gaseous carbon sources contributing to decreased CO\({}_{2}\) and CH\({}_{4}\) emissions in PFS. Figure 5 presents the total carbon emissions (CH\({}_{4}\)-C + CO\({}_{2}\)-C) of PFS and CTL. As previously observed, cumulative CO\({}_{2}\) and CH\({}_{4}\) emissions decreased by 23% and 44% in PFS compared with CTL, respectively. On the 7 th day of storage, CTL and PFS showed higher carbon emissions in the form of CO\({}_{2}\) compared with CH\({}_{4}\). CO\({}_{2}\) accounted for 66% and 84% of the total carbon emissions in CTL and PFS, respectively. On the 14 th day of storage, the contribution of carbon emissions from CH\({}_{4}\) in CTL increased, accounting for 65% of the total carbon emissions. PFS increased CH\({}_{4}\)-C emissions compared with the previous week, but CO\({}_{2}\) still accounted for about half of the total carbon emissions. During the subsequent storage period, the proportion of CO\({}_{2}\) in the total carbon emissions was dominant in PFS until day 49 (average of 66% of total carbon emissions) and in CTL until day 42 (average of 78% of total carbon emissions). The percentage of CH\({}_{4}\) in total carbon emissions ranged from 16 to 46% and 14 to 65% in PFS and CTL, respectively, comparable to the maximum values of 50-70% reported in other studies [16; 50; 51]. In the storage of pig slurry, CO2 emissions exceed those of CH4 when assessed based on total carbon emissions. However, when expressed in terms of CO2-eq., CH4 significantly influences greenhouse gas emissions. During the experimental period, the emissions of CH4-C and CO2-C converted to CO2-eq. displayed a different trend from the total carbon emissions (Table 4). The results of this study indicate that, in both PFS and CTL, the amount of CH4 emissions converted into CO2-eq. exceeded that of CO2 emissions throughout the entire storage period. This persistent pattern of CH4 dominance in the total carbon emissions is consistent with CH4 accounting for about 93% and 95% of the total carbon emissions in PFS and CTL, respectively. These findings are in contrast to those presented in Figure 5. Furthermore, PFS was found to have approximately 43% less impact on greenhouse gas emissions than CTL. Overall, these results suggest that CH4 emissions during the 56-day storage period are a significant contributor to greenhouse gas emissions in pig slurry storage and should be carefully monitored and managed in efforts to mitigate the environmental impacts of agricultural waste management practices. Although CH4 emissions from pigs contribute a smaller proportion compared with the cattle's impact from enteric fermentation on greenhouse gas generation, their significance remains pronounced in CH4 production through their integral role in manure management [1].