Physiology Methane Evidence Mapping

Five rapid evidence mapping studies of published literature and expert thinking (including through the use of surveys) to address the five questions listed below. Emphasis on identifying novel thinking and new opportunities, including ideas that are quite speculative, as well as reviewing early work that was not followed up, perhaps because of the difficulty of techniques available at that time (1960s and 1970s). The purpose is to identify opportunities that can be pursued in new experimental work, particularly recognising the new experimental techniques that are now available for physiology studies, and the opportunity to conduct more work in developing countries. The interface between measurements and modelling will remain important for progress in this area. Outputs from these studies will be discussed with a group of rumen modellers to develop scenarios using existing models or new models to determine which relationships merit investment in experiments.

Each section will be led by a post-doctoral researcher from within the consortium, supported by senior researchers across the collaborating organisations (SRUC (UK), Teagasc (Ireland), Aarhus University (Denmark), ETH Zurich and University of Zurich (both Switzerland)). All partners will participate in a face-to-face kick-off workshop at the start of the project and the five reviews will each run in parallel. It is anticipated that the scope of reviews will evolve as new opportunities and interactions become evident. The interaction between methane emissions and nutrient utilisation (absorption and partitioning) is a particular focus because progress in identifying 'win-win' approaches delivering both reduced methane emissions and increased productivity (feed efficiency) will be important for adoption of technologies.

i) What evidence is there for changes in methane production being causally linked to any of the four main categories of physiological process: (a) feeding behaviour and feed intake patterns, (b) particulate passage rates from the rumen, rumen volume, rumen motility and rumination activity, (c) liquid passage rates from the rumen, water consumption and saliva production, (d) proportions of different short-chain fatty acids (SCFA) produced in the rumen;

ii) What do we know about feeding behaviour and intake patterns, and their effects on nutrient absorption from different diets;

iii) What do we know about particulate passage rates from the rumen, rumen volume, rumen motility and rumination activity, and how important they are in changing nutrient absorption from different diets;

iv) What do we know about how water, saliva and liquid passage rate influence nutrient absorption from different diets;

v) What do we know about how differences in SCFA production ratios in the rumen are likely to influence nutrient partitioning.