Submitted to: Proceedings of American Registry of Professional Animal Scientists
Publication Type: Abstract Only
Publication Acceptance Date: 10/22/2018
Publication Date: N/A
Technical Abstract: Complex plant polymers, such as cellulose, are difficult to break-down and provide little nutritional value if not further processed. Ruminants, such as cattle, sheep, and goats, have developed a specialized digestive system that is capable of degrading these complex polysaccharides and to turn them into volatile fatty acids (VFA) and microbial protein (MP) that are absorbed by the animal. The first and largest portion of the ruminant digestive tract, eponymously named the rumen, is a large muscular sack containing anaerobic microbial species and the digesta they process. The key players of ruminant digestion consist of members of all three kingdoms of life. The most numerous occupants of the rumen are from the Bacterial superkingdom, and they comprise approximately 60% of the total living biomass in the rumen lumen. Members of the Archaeal superkingdom are also present in the rumen and are mostly comprised of species that produce methane, a potent greenhouse gas. Finally, a large proportion (20-50%) of the living biomass in the rumen is comprised of microscopic Eukaryotes consisting of protists and fungal species. Each of the microscopic components of the rumen occupy a unique metabolic niche and many of the digestive pathways that they contribute have been very well-characterized by ruminant microbiologists in the past several decades. While we are able to derive a larger picture of the activity of microbes in the rumen, there is substantial difficulty in fully characterizing all of the occupants of the rumen and predicting their proliferation in response to stimulus.