This is particularly due to the presence of methanogens (microbes that produce methane) in their digestive systems. Considering methane has a global warming potential (GWP) approximately 21 times greater than carbon dioxide, these livestock are often used as scapegoats to justify climate change inaction.
However, there is potential for widespread breakthroughs in dealing with excessive, ruminant-derived methane emissions. Inspiration has been sought from their marsupial counterparts: kangaroos. ‘Roos’ utilise acetogens, rather than methanogens for metabolising plant material, subsequently producing acetic acid. It is believed that these methanogens, which are generally slow-growing, would not to able to survive after passing through a kangaroo’s forestomach.
Associate Professor Athol Klieve from the University of Queensland, Australia, has been collaborating with fellow microbiologists to develop breakthroughs in this field of research. If proven successful, it could drastically change the impact of livestock on greenhouse gas emissions (GHGs). Meat and dairy products account for approximately half the overall food-related GHGs, which, in turn, account for 18% of global GHGs (CO2-e). Furthermore, cattle and sheep alone contribute to roughly 11% of Australia’s total methane emissions.
The livestock industry, overall, is a major contributor to GHGs, with the rearing of cattle contributing to approximalely 16 tonnes of CO2-equivalent (when factoring in all inputs and resources per tonne of meat. This could reach up to 22.6 tonnes of CO2-e per tonne of meat. This is in contrast to chickens and pigs, which emit 4.6 and 6.4 tonnes of CO2 respectively.
Notwithstanding these figures, it is paramount to remember that cattle can readily metabolise grasses and graze on areas that are otherwise inappropriate for other livestock; for example, less-fertile soils. Hence, cattle and sheep will still play a critical role in making use of otherwise-underutilised places, to ultimately satisfy a plethora of palates in our modern world.
In summary, whilst official studies comparing ruminants and kangaroos date back to 1965 (and possibly earlier), an ongoing amount of thorough and ongoing research will be critical to the program’s success. Whilst the days of ‘low-carbon’, ‘guilt-free’ bovine gastronomy are still a while away, there is a positive outlook.
Table source: http://randd.defra.gov.uk/Document.aspx?Document=IS0205_3959_FRP.doc