International Symposium on Ruminant Physiology: The holobiont concept in ruminant physiology-More of the same, or something new and meaningful to food quality, food security, and animal health?

The holobiont concept has emerged as an attempt to recognize and describe the myriad interactions and physiological signatures inherent to a host organism, as affected by the microbial communities that colonize and co-inhabit the environment within which the host resides. The field acknowledges and draws upon principles from evolution, ecology, genetics, and biology, and in many respects has been pushed by the advent of high throughput DNA sequencing and, to a lesser extent, other omics-based technologies. Despite the explosion in data generation and analyses, much of our current understanding of the human and ruminant holobiont is based on compositional forms of data and thereby, restricted to describing host phenotypes via associative or correlative studies. So, where to from here? We will discuss some past findings arising from ruminant and human gut microbiota research and seek to evaluate the rationale, progress, and opportunities that might arise from the holobiont approach to the ruminant and human host. In particular, we will consider what is a "good" or "bad" host gastrointestinal microbiome in different scenarios, as well as potential avenues to sustain or alter the holobiont. Although the holobiont approach might improve food quality, food security, and animal health, these benefits will most likely be achieved via a judicious and pragmatic compromise in data generation, both in terms of its scale as well as its generation, in context with the forgotten knowledge of ruminant and human physiology.