Addition of herbal supplement to in vitro fermentation of dairy cow rumen modulates the microbial community

The diet of cows has a great impact on their ruminal environment altering the microbiota and metabolomics of the rumen. However, instead of changing the overall diet, feed can be supplemented with herbs to allow this modulation. We investigated the effect in vitro by fermenting herbs in rumen liquid from donor cows, analyzing the microbial community that developed, to evaluate the safety and possible benefits of the procedure. Materials and Methods Ruminal liquid was collected from three different dairy cows and mixed with media plus plant roots or one of six different herbs. As controls we tested: a bottle with only media, a rumen bottle without any supplement and a bottle with supplementation of regular grass hay. Each mixture was fermented for 24h. Microbial DNA of rumen samples was extracted with commercial kit and sequenced by Illumina sequencing of V3 and V4 region of bacterial 16S rDNA. The raw reads have been analysed by QIIMNE pipeline and bacterial taxa identified by means of the greengenes 16S database. The alpha and beta diversities have been calculated by QIIME2 scripts. Results The supplementation produced distinct microbiota significantly different ftom each other. Plant root supplementation caused the highest differences in rumen microbiota. Bacteriodales was the most abundant order, except for plant root supplemented fermentations, where Streptococcus was the most abundant genus. Conclusion Different herbal supplementation can alter the microbial community of rumen in vitro. The Streptococcus abundance in plant root supplemented rumen samples could be a cause for concern, as the increase in Streptococcus genus in rumen microbiota could be related to a lowering of pH in rumen and cause acute acidosis to the dairy cows.