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

In this study, the effects of seven pure plant secondary metabolites (PSMs) on rumen fermentation, methane (CH4 ) 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 CH4 production. However, effective concentrations differed among individual PSMs. The lowest concentrations that reduced (p < .05) CH4 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) CH4 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 CH4 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 CH4 production. The PSMs tested in this study demonstrated considerable impact on rumen bacterial communities even at the lowest concentrations that decreased CH4 production. The findings from this study may help to elucidate how PSMs affect rumen bacterial fermentation.

In vitro Screening of Essential Oil Active Compounds for Manipulation of Rumen Fermentation and Methane Mitigation.

The objective of this study was to investigate the effects of 11 active compounds of essential oils (ACEO) on rumen fermentation characteristics and methane production. Two trials were conducted. In trial 1, ACEO (eugenol, carvacrol, citral, limonene, 1,4-cineole, p-cymene, linalool, bornyl acetate, α-pinene, and ß-pinene) at a dose of 1,000 µL/L were incubated for 24 h in diluted rumen fluid with a 70:30 forage:concentrate substrate (16.2% crude protein; 36.6% neutral detergent fiber). Three fistulated Holstein cows were used as donors of rumen fluid. The reduction in methane production was observed with nine ACEO (up to 86% reduction) compared with the control (p<0.05). Among these, only limonene, 1,4-cineole, bornyl acetate, and α-pinene did not inhibit volatile fatty acid (VFA) production, and only bornyl acetate produced less methane per mol of VFA compared with the control (p<0.05). In a subsequent trial, the effects on rumen fermentation and methane production of two concentrations (500 and 2,000 µL/L) of bornyl acetate, the most promising ACEO from the first trial, were evaluated using the same in vitro incubation method that was used in the first trial. In trial 2, monensin was used as a positive control. Both doses of bornyl acetate decreased (p<0.05) methane production and did not inhibit VFA production. Positive effects of bornyl acetate on methane and VFA production were more pronounced than the effects of monensin. These results confirm the ability of bornyl acetate to decrease methane production, which may help to improve the efficiency of energy use in the rumen.

High serum levels of antibodies against the recombinant 70 kDa ribonucleoprotein are useful for diagnosing mixed connective tissue disease.

BACKGROUND: Anti-Sm antibodies and anti-RNP antibodies are considered to be diagnostic markers of systemic lupus erythematosus (SLE) and mixed connective tissue disease (MCTD). However, cross-reactivity between the antibodies diminishes their discriminating specificity between these diagnoses. OBJECTIVE: We examined whether we could achieve better differentiation between these two disease entities using recombinant antigens to RNP70 and SmD and quantitative immunoassays. PATIENTS/METHODS: Sera from 51 patients with SLE and 10 patients with MCTD and from a control group of 59 patients were used in a cross-sectional setting. Semiquantitative ELISAs for the detection of antibodies to RNP-70, RNP-A, RNP-C, SmBB' and SmD were used and the results were compared to conventional ELISA tests using U(1)-snRNP and a mixture of SmBB' and SmD as antigenic substrates. RESULTS: Sera from MCTD patients showed higher levels of anti-RNP-70 antibodies than sera from SLE patients. Levels of anti-SmBB' or anti-SmD antibodies were not significantly different between SLE and MCTD sera. However, the presence of antibodies directed against SmD was more frequent in SLE. CONCLUSIONS: Our results suggest that the use of RNP-70 and SmD antigens may increase the practical value of immunoassays used to confirm a diagnosis of SLE or MCTD in patients with connective tissue disease.