Innovation and exploitation of biomarkers of rumen function efficiency in dairy cows using metabolomics technologies

J Moorby, M Rose & J Draper

Dairy cows typically use feed protein with an efficiency of conversion into milk protein of about 25%. This means that 75% of feed protein is excreted, contributing to pollution problems in the form of ammonia and nitrous oxide (N2O). Inefficient rumen utilisation of feed proteins is the greatest source of excreted N, although it is difficult to monitor rumen fermentation using non-invasive methods.

IBERS is involved in a new EU FP7 research project (Rednex; worth €8M over 5 years in total) to investigate ways of reducing N excretion from dairy cows. It is based around current mathematical models of the cow and the rumen, and aims to investigate the effects of low N feeding in more detail. The best way to reduce N excretion is to reduce N intake; production can be maintained by increasing the efficiency of use of feed N. IBERS is formally involved in several of the project’s workpackages, concentrating on the effects of protozoa on rumen function and using various metabolomics techniques to refine and discover existing and novel biomarkers of rumen function. The latter workpackage is being led by Jon Moorby. Biomarkers of microbial protein production currently in use include urinary purine derivatives and milk odd- and branched-chain fatty acids; novel biomarkers of rumen efficiency that could be used to feed back into scientific and applied (on-farm) models of the dairy cow will help to refine ration formulation and reduce the environmental footprint of dairy production.

Approaches
The progressive and independent-thinking PhD student will be involved in IBERS Rednex activities. Additionally, there would be opportunity to interact with researchers on FSA-funded N05 projects concerned with human nutritional metabolomics. The student will work on in vitro (rumen function) and in vivo (sheep and dairy cow) rumen function studies. Although project milestones are already set, the student will have the opportunity to carry out their own studies (particularly in vitro) alongside those already planned, relating rumen function to metabolites in blood, urine and milk. He or she will learn lab methods such as GC-MS, LC-MS, and FTIR analyses, and methods for the analysis of the data produced as a result. Publication of the results of this work will be achieved in high impact factor journals.