Influence of yeasts supplementation on microbiome composition of liquid fraction rumen content of lactating cows

Dietary supplements are widely used in dairy cows to increase productivity by improving rumen metabolism, but their effectiveness is proven only for few products. The reason is that host and dietary interactions may alter the efficacy of supplements, and remains uneasy to understand which rumen microbial species are involved and in which way. Yeast, in particular Saccharomyces cerevisiae, has been tested on dairy cows in different strains or commercial products with a number of positive effects such as increased DMI and milk production, improved diet digestibility, stabilized rumen pH or stimulated rumen bacteria growth. However, in ruminant diets there are many other reports of no response or negative response, because of the deep influence of diet, yeast strain and commercial formulation on its effectiveness. In this study a gene centric metagenomics approach and next generation sequencing technology were used to investigate simultaneously high amount of sequences from a large number of microorganisms from the liquid rumen content, allowing metagenomic investigations of different microbiomes and to investigate the variability of potential “rumen phenotypes” and the bases of the diet-rumen microbiome interactions. At the best of our knowledge, rumen metagenome data generated from are very few and no information is still available for the rumen liquid fractions. In this study, a gene centric metagenomic approach were used to investigate microbiome composition of fluid fraction rumen content in twelve lactating dairy cows without or with supplementation of 2 forms of dried Saccharomyces cerevisiae in a potato protein support. The aim is to provide an insight of bacteria composition and its biodiversity, a basis for further investigation in ruminant science.