AUTHOR=Bagheri Varzaneh Maryam , Klevenhusen Fenja , Zebeli Qendrim , Petri Renee 

TITLE=Scrophularia striata Extract Supports Rumen Fermentation and Improves Microbial Diversity in vitro Compared to Monensin

JOURNAL=Frontiers in Microbiology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2018.02164

DOI=10.3389/fmicb.2018.02164

ISSN=1664-302X

ABSTRACT=<p>In the search for natural alternatives to antibiotic feed additives, we compared the efficacy of two doses of <italic>Scrophularia striata</italic> extract [<italic>S. striata</italic>-Low at 40 and <italic>S. striata</italic>-High at 80 mg g<sup>-1</sup> dry matter (DM)] with monensin (monensin) and a negative control in the modulation of rumen fermentation, methane production and microbial abundance <italic>in vitro</italic>. Microbes were investigated using qPCR and 16S rRNA targeted sequencing. Data showed that the addition of <italic>S. striata</italic> increased production of total short chain fatty acids (SCFA) in comparison to both monensin and control (<italic>P</italic> = 0.04). The addition of <italic>S. striata</italic> increased acetate production, and increased propionate at the higher dosage (<italic>P</italic> &lt; 0.001). Supplementation of <italic>S. striata</italic> lowered methane production (<italic>P</italic> &lt; 0.001) compared to control but with no effect compared to monensin. Ammonia concentration decreased by 52% (<italic>P</italic> &lt; 0.001) with <italic>S. striata</italic>-High supplementation (4.14 mmol L<sup>-1</sup>) compared to control, which was greater than that of monensin (36%). The diversity of rumen bacteria was reduced (<italic>P</italic> &lt; 0.001) for monensin and <italic>S. striata</italic> for both the number of observed OTUs and the Chao1 index. Quantitative analysis of Protozoa showed a decrease in the monensin treatment (<italic>P</italic> = 0.05) compared to control. Archaea copy numbers decreased equally in both <italic>S. striata</italic>-High and monensin treatments compared to the control group. Supplementation with <italic>S. striata</italic> increased relative abundances of <italic>Fibrobacteres</italic> (<italic>P</italic> &lt; 0.001) and <italic>Planctomycetes</italic> (<italic>P</italic> = 0.001) in comparison to both the control and monensin treatments. Significant negative correlations were observed between the abundances of <italic>Bacteroides, Fusobacterium</italic>, and <italic>Succinivibrio</italic> genera and methane (<italic>r</italic> &gt; -0.71; <italic>P</italic> ≤ 0.001). The abundance of <italic>Fibrobacter</italic> genera and total SCFA (<italic>r</italic> = 0.86), acetate (<italic>r</italic> = 0.75), and valerate (<italic>r</italic> = -0.51; <italic>P</italic> &lt; 0.001) correlated positively. These results suggest that <italic>S. striata</italic> supplementation at 80 mg g<sup>-1</sup> DM inclusion, similar to monensin, supports rumen fermentation, lowers methane and ammonia production. However, <italic>S. striata</italic> supported rumen fermentation toward higher total SCFA and propionate production, while unlike monensin still supported a diverse rumen microbiome and an increase in cellulolytic bacteria such as <italic>Fibrobacter</italic>.</p>