This experiment was conducted to study the effects of different concentrations of polyphenols of Paulownia Clon In Vitro 112® 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.

This study aims to perform population analysis of the rumen ciliated protozoa of the free-living European bison (wisent, Bison bonasus, Linnaeus). The samples of the rumen fluid from the 18 bison subjected to the controlled culls within the free-ranging population in the Bialowieza primeval forest in Poland were collected and examined. The examined ciliates population consisted of the species of the families Isotrichidae and Ophryoscolecidae. There were 12 genera (Isotricha, Dasytricha, Diplodinium, Elytroplastron, Entodinium, Eodinium, Epidinium, Eremoplastron, Eudiplodinium, Metadinium, Ophryoscolex, and Ostracodinium) and 32 morphospecies of the ciliates. We observed the prevalence of a type B protozoan population (56% animals) with the typical Epidinium and Eudiplodinium genera members. Other examined animals possessed the mixed A–B population with Ophryoscolex genus, distinct for type A ciliate population. The average total ciliates count was 2.77 ± 1.03 × 105/ml (mean ± SD). The most abundant genera were Entodinium, 83%, and Dasytricha, 14%. The abundance of other genera was <1% of the total count. Within the 16 Entodinium species determined, the most abundant species was Entodinium nanellum (16.3% of total ciliates count). The average Shannon–Wiener diversity index was 2.1 ± 0.39, evenness was 0.7 ± 0.11, and species richness was 24 ± 3.0 (mean ± SD). Our study is the first report on the population composition and diversity of rumen ciliates of European bison. The composition and counts of ciliate genera and species were similar to the composition and counts of the rumen ciliated protozoa of American bison and many other kinds of free-living and domestic ruminants. Our European bison ciliate population analysis has shown medium ciliate density and high diversity typical for large free-living ruminants with mixed feeding behavior.

Paulownia is a fast-growing tree that produces a huge mass of leaves as waste that can be used as a feed source for ruminants. The previous study showed that phenolic compounds were the most active biological substances in Paulownia leaves, which affected the ruminal parameters and methane concentration. However, there are no scientific reports on the Paulownia leaves extract (PLE) containing phenolic compounds for their mode of action in the rumen. Phenolics constituted the main group of bioactive compounds in PLE (84.4 mg/g dry matter). PLE lowered the concentration of ammonia, modulated the VFA profile in the ruminal fluid, and decreased methane production. The PLE caused a significant reduction of in vitro dry matter degradability, reduced the number of methanogens and protozoa, and affected selected bacteria populations. PLE had a promising effect on the fatty acid profile in the ruminal fluid. Paulownia as a new dietary component or its extract as a feed additive may be used to mitigate ruminal methanogenesis, resulting in environmental protection and reducing ruminal biohydrogenation, improving milk and meat quality.