Effects of pure plant secondary metabolites on methane production, rumen fermentation and rumen bacteria populations in vitro

Abstract

In this study, the effects of seven pure plant secondary metabolites (PSMs) on rumen fermentation, methane (CH ) production and rumen bacterial community composition were determined. Two in vitro trials were conducted. In trial 1, nine concentrations of 8-hydroxyquinoline, α-terpineol, camphor, bornyl acetate, α-pinene, thymoquinone and thymol were incubated on separate days using in vitro 24-hr batch incubations. All compounds tested demonstrated the ability to alter rumen fermentation parameters and decrease CH production. However, effective concentrations differed among individual PSMs. The lowest concentrations that reduced (p < .05) CH production were as follows: 8 mg/L of 8-hydroxyquinoline, 120 mg/L of thymoquinone, 240 mg/L of thymol and 480 mg/L of α-terpineol, camphor, bornyl acetate and α-pinene. These concentrations were selected for use in trial 2. In trial 2, PSMs were incubated in one run. Methane was decreased (p < .05) by all PSMs at selected concentrations. However, only 8-hydroxyquinoline, bornyl acetate and thymoquinone decreased (p < .05) CH relative to volatile fatty acids (VFAs). Based on denaturing gradient gel electrophoresis analysis, different PSMs changed the composition of bacterial communities to different extents. As revealed by Ion Torrent sequencing, the effects of PSMs on relative abundance were most pronounced in the predominant families, especially in Lachnospiraceae, Succinivibrionaceae, Prevotellaceae, unclassified Clostridiales and Ruminococcaceae. The CH production was correlated negatively (-.72; p < .05) with relative abundance of Succinivibrionaceae and positively with relative abundance of Ruminococcaceae (.86; p < .05). In summary, this study identified three pure PSMs (8hydroxyquinoline, bornyl acetate and thymoquinone) with potentially promising effects on rumen CH production. The PSMs tested in this study demonstrated considerable impact on rumen bacterial communities even at the lowest concentrations that decreased CH production. The findings from this study may help to elucidate how PSMs affect rumen bacterial fermentation.

Effects of Thymol Supplementation on Goat Rumen Fermentation and Rumen Microbiota In Vitro

“…In the present study, thymol at doses of 100 mg/L and 200 mg/L tended to increase butyrate concentration while a dramatical decrease was observed with 400 mg/L of thymol supplementation. The increase in butyrate concentration is consistent with previous study by Joch et al [ 13 ] with 240 mg/L thymol supplemented to dairy cow in vitro. The dramatical decrease in butyrate concentration caused by highest dose implicates a strong inhibitory effect of high dose thymol in the present study, which is in accord with previous results, i.e., total gas production, IVDMD, and total VFA production.…”

“…Thymol (5-methyl-2-isopropylphenol) is one of the active compounds in EOs derived from Thymus and Origanum plants [ 11 , 12 ]. Dosages of thymol higher than 240 mg/L have been reported to affect rumen fermentation with a decrease in methanogenesis and altered rumen bacteria composition in lactating cows in vitro [ 13 ]. A similar effect on rumen methane reduction was found by Castañeda-Correa et al [ 14 ] with 200 mg/L thymol supplemented in vitro, whereas no effect was found on dry matter digestibility and methanogenic bacteria except for individual bacterial population changes within rumen microorganisms.…”

A Mixed Phytogenic Modulates the Rumen Bacteria Composition and Milk Fatty Acid Profile of Water Buffaloes

“…The major fermentation product of this bacterial family is succinate which is subsequently converted to propionate in the rumen, so it creates the possibility of competition between Succinivibrioanceae and methanogens to utilize hydrogen as a substrate to produce succinate and propionate instead of methane. In line with this, greater abundance of Succinivibrioanceae was negatively correlated with methane production (R = −0.72) in cattle (102). Substantially higher abundance of Succinivibrioanceae has been observed in beef cattle with low methane production compared to cattle with higher emissions (103).…”

Effect of dry medicinal plants (wormwood, chamomile, fumitory and mallow) on in vitro ruminal antioxidant capacity and fermentation patterns of sheep

“…Our results are consistent either with the direct effects of the bioactive compounds of Plants on methanogens or the indirect effect on reducing hydrogen production as a substrate for micro‐organisms (Tavendale et al, 2005). Even though the effect of a medicinal plant enriched diet on gastrointestinal fermentation patterns in vitro can usually be within the physiological range, the efficacy of PSM on rumen fermentation, methane production and rumen bacterial communities can vary considerably depending on the type, sources, molecular weight and doses of the diet (Joch, Mrázek, Skřivanová, Čermák, & Marounek, 2018; Patra et al, 2017).…”