## 4 Discussion  
### In Vitro Gas and Methane Production  
Low in vitro gas production parameters observed in T2 and T4 could be partly explained by the negative effect of tannins on ruminal fermentation [29]. The values of the \begin{table}
\begin{tabular}{l c c c c c} \hline \hline  & \multicolumn{4}{c}{**Treatments**} & \multirow{2}{*}{**SEM**} & \multirow{2}{*}{**\(p\) < Value**} \\ \cline{2-2} \cline{5-6}  & **T1** & **T2** & **T3** & **T4** \\ \hline TDIVMD\({}_{48\,h}\) (mg\({}^{-1}\) 100 mg DM) & 667  & 622  & 654  & 642  & 2.4 & 0.030 \\ pH & 6.60 & 6.6 & 6.6 & 6.5 & 0.017 & 0.854 \\ N-NH3, (mg dL\({}^{-1}\)) & 12.6  & 8.7  & 11.5  & 9.3  & 0.152 & 0.024 \\ TVFA, (mM/L) & 10.6  & 6.5  & 7.9  & 7.5  & 0.281 & 0.002 \\ Volatile fatty acids (molar & \\ Acetate & 66.8  & 72.0  & 67.7  & 70.5  & 0.161 & 0.003 \\ Propionate & 24.4  & 18.2  & 22.3  & 19.3  & 0.674 & 0.033 \\ Butyrate & 5.7 [FOOTNONOTE:8]Footnote 8: footnotemark: [ENDFOOTNOTE] & 9.1  & 9.3  & 9.0  & 0.247 & 0.027 \\ A:P ratio & 2.7 & 3.9 & 3.0 & 3.6 & 0.143 & 0.911 \\ MBS (mg\({}^{-1}\) g DM) & 165.2  & 132.2  & 147.4  & 145.1  & 1.13 & 0.007 \\ PF (mg TDMD/mL gas) & 6.0  & 6.5 [FOOTNONONONOTE:8]Footnote 8: footnotemark: [ENDFOOTNOTE] & 6.5 [FONONONOTE:8]Footnote 8: footnotemark: [ENDFOOTNOTE] & 6.3  & 1.05 & 0.050 \\ \hline \hline \end{tabular} \({}^{a}\)Red Means within the same row with various superscripts are significantly different (\(p\) < 0.05). TDMD\({}_{48\,h}\) = True degradability dry matter; TVFA = Total volatile fatty acids MBS = Microbial biomass synthesis; PF = Partition factor. SEM = Standard error of mean.  
\end{table} 
Table 6: True degradability in vitro dry matter, fermentation ruminal patterns and microbial biomass synthesis of experimental treatments. \begin{table}
\begin{tabular}{l c c c c c c} \hline \hline  & \multicolumn{4}{c}{**Treatments**} & \multirow{2}{*}{**SEM**} & \multirow{2}{*}{**\(p\) < Value**} \\ \cline{2-2} \cline{5-6}  & **T1** & **T2** & **T3** & **T4** & \\ \hline Total bacteria  & 14.7 & 14.9 & 15.2 & 15.4 & 0.030 & 0.22 \\ Celulolytic bacteria  & 7.6 & 7.6 & 5.0 & 0.076 & 0.98 \\ Protozoa  & 16.6  & 7.3  & 13.3  & 10.2  & 0.082 & 0.04 \\ Total methanogens  & 14.2  & 13.5  & 13.8  & 13.6  & 0.066 & 0.05 \\ Methanogen:bacteria ratio & 0.95 & 0.91 & 0.91 & 0.88 & 0.091 & 0.88 \\ YATP (g microbial cells mol\({}^{-1}\) ATP) & 24.0 & 22.2 & 24.0 & 23.3 & 0.61 & 0.930 \\ \hline \hline \end{tabular} \({}^{a}\)Red Values with different letters in the same row are statistically different (\(p\) < 0.05); \({}^{b}\)Log [mgDNAg-1 RC]; \({}^{b}\) (\(\times 10^{4}\) CFU\({}^{-1}\) mL); \({}^{d}\) (\(\times 10^{6}\) CFU\({}^{-1}\) mL); RC = Ruminal content; CFU = Colony forming units. SEM = Standard error of mean.  
\end{table} 
Table 7: Ruminal microbial population of the experimental treatments after in vitro incubation with rumen fluid. in vitro gas production parameters obtained in the current study are in partial agreement with the findings of [PERSON] et al. [30] and [PERSON] et al. [31], who evaluated in vitro conditions phenolic compounds and alfalfa hay in addition to concentrates in a 50:50 range, respectively. Despite the nutrient supply of LLL leaves and PP in T2, T3, and T4, the \"a\", \"b\", \"GPP\", and \"Kd\" values were lower than the control treatment where alfalfa hay was a main source of forage, which could be due to the fact that rumen microbes were stimulated, as well as the digestibility of the incubated substrate, resulting in better gas production kinetics [32]. As regards to the decrease in CH4 production recorded in T2 and T4 could be attributed to the content of condensed tannins (CT) [PERSON] et al. [33]. This suggests that CT is at least partially responsible for this effect. According to [PERSON] et al. [34], LLL inhibits CH4 production both in vitro and in vivo conditions. The reduction in CH4 production is attributable not only to CT but could be partly due to differences in other components of the diets, mainly cell wall components [35].