## 3 Results and Discussion
### In Vitro Ruminal Fermentation of Silages: Ruminal Gas Production Kinetics  
The technique of gas production was used as an indicator of the kinetics of the ruminal fermentation of silages, as the amount of gas produced was directly related to the amount of organic matter fermented [33]. The gas production kinetics parameters and gas production curves for all of the tested samples are shown in Table 3 and Figure 1, respectively. Compared with the CON silage, the addition of either formic acid or urea and molasses did not affect the potential gas production (PGP) and the fractional rate of gas production (\(c\)), but the addition of the three additives in FAUM silage decreased (\(p<0.05\)) PGP and increased (\(p<0.05\)) \(c\). The greater \(c\) value in the FAUM silage was consistent with the rapid degradation of both urea and molasses [34; 35]. Although lower gas production is related to lower degradability, it has to be taken into account that ruminal fermentation of CP produces less gas than that of carbohydrates, and thus high-protein feeds can have lower gas production during in vitro fermentation [35; 36]. This could help explain the lower PGP of FAUM silage. The observed reduction (\(p<0.05\)) in Lag (time before fermentation starts) in all of the treated silages compared with the CON silage agreed well with the rapid fermentation of molasses and with the hypothesis that formic acid could accelerate the start of fermentation because of the increased water-soluble carbohydrate content observed previously in the silages treated with this acid [37; 38]. Our results agreed well with previous studies, showing improvements in gas kinetics when urea and molasses were added to sugarcane bagasse silages [34] or Leucaena silages [35]. The greater (\(p<0.05\)) AGPR observed for all of the treated silages than for the CON silage supported these results, as AGPR is the gas production rate in the initial phases of in vitro fermentation. \begin{table}
\begin{tabular}{l c c c c c c c c} \hline \hline  & \multicolumn{6}{c}{**Silage Treatment**} \\ \cline{2-9}
**Item** & **CON** & **FA** & **UM** & **FAUM** & **SEM 2** & \(p\) = &
\begin{tabular}{c} **Thypha** \\ **Pre-Ensiling** \\ \end{tabular} & **Triticale Hay** \\ \hline Crude ash & 123 b  & 117 a  & 135 c  & 123 b  & 1.2 & \(<\)0.001 & 1120 & 86.0 \\ Crude protein & 114 a  & 115 a  & 222 c  & 2.9 & \(<\)0.001 & 119 & 109 \\ Ether extract & 39.7 & 36.9 & 46.4 & 48.9 & 4.52 & 0.081 & 48.4 & 23.8 \\ Neutral detergent fibre & 694 bc  & 702 c  & 666 ab  & 643 a  & 7.6 & 0.002 & 691 & 587 \\ Acid detergent fibre & 411 & 404 & 415 & 395 & 10.8 & 0.581 & 401 & 315 \\ Acid detergent lignin & 69.2 ab  & 63.1 a  & 73.3 b  & 65.8 a  & 1.64 & 0.012 & 66.9 & 37.4 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Chemical composition (g/kg of dry matter) of typha silages treated with no additive (CON); with formic acid (FA); with urea and molasses (UM); or with formic acid, urea, and molasses (FAUM); of typha biomass before ensiling and of a triticale hay used as a reference 1. The treatment with urea and molasses (UM and FAUM) led to greater PDMD compared with the CON silage, possibly due to an increase in the degradability of the structural carbohydrates, as has been previously reported for silages of other forages [35]. In contrast, the use of formic acid decreased (\(p\) < 0.05) PDMD, which was difficult to explain, but this effect has also been previously reported by [PERSON] et al. [39] in maize silage. During the ensiling period, some fermentable substances were lost, which could explain the PGP reduction observed in the silages compared with the pre-ensiling typha (Table 4). Compared with the triticale hay used as a reference, all typha silages presented lower values of PGP, AGPR, and PDMD, with the exception of UM and FAUM silages, which had a similar PDMD.