The Effect of Different Concentrations of Total Polyphenols from Paulownia Hybrid Leaves on Ruminal Fermentation, Methane Production and Microorganisms

Simple Summary: Paulownia hybrid leaves, a wood industry by-product, have been recognized not only as a valuable dietary ingredient for ruminants but also as a rich source of bioactive components such as polyphenolic compounds. Hence, this study was carried out to assess the effects of different concentrations of Paulownia hybrid leaves rich in polyphenols or their particular part on in vitro ruminal fermentation, methane production and microbial populations. Paulownia leaves with high (PLH), medium (PLM), and low levels of polyphenols (PLL) were used from different plantation areas. Lamina (PLLA) and twigs (PLT) of the leaves were also collected from the PLM plantation. Most of the basic nutrient content was similar to dehydrated alfalfa. The use of Paulownia leaves with high content of total polyphenols (PLH and PLLA) or high content of fiber (PLT) lowered ruminal methane production. Reduction of methane production was attributed to the lowering of methanogen populations in PLH and PLLA without affecting substrate degradability and volatile fatty acid concentrations, but in PLT, it was due to decreased in vitro degradability causing decreases in some ruminal parameters, mainly total volatile fatty acids. This experiment was conducted to study the effects of different concentrations of polyphenols of Paulownia Clon In Vitro 112(R) leaves or their particular parts on in vitro ruminal fermentation, methane production and microbial population. Paulownia leaves with high (PLH; 31.35 mg/g dry matter (DM)), medium (PLM; 26.94 mg/g DM), and low level of polyphenols (PLL; 11.90 mg/g DM) were used from three plantation areas. Lamina (PLLA; 33.63 mg/g DM) and twigs (PLT; 2.53 mg/g DM) of leaves were also collected from the PLM plantation. The chemical analyses of Paulownia leaves indicated that the content of the most basic nutrients (e.g., crude protein concentration of 185 g/kg of DM) were similar to dehydrated alfalfa. The in vitro results showed that the use of Paulownia leaves with the highest content of total polyphenols (PLH and PLLA) decreased methane production, methanogens numbers, and acetate to propionate ratio. In PLT, lowered methane production was followed by reduced substrate degradability and volatile fatty acid (VFA) concentration along with higher acetate to propionate ratio. Therefore, reduction of methane production in PLH and PLLA was attributed to the lowered methanogen population, whereas in PLT it was caused by decreased substrate degradability with the resultant of limited hydrogen availability to the methanogens.

Automated summary

This study evaluated the effects of polyphenol-rich Paulownia hybrid leaves on in vitro ruminal fermentation, methane production, and microbial populations. The results showed that leaves with high polyphenol content reduced methane production, while the decrease in methane production in twigs was mainly attributed to decreased substrate degradability.