Cows’ farts have long been recognised as a contributor to climate change. Their digestion creates methane as a by-product and that methane is 25 times more effective than carbon dioxide at trapping heat in the atmosphere, although it only remains for a decade.
Methane is a large component of the national greenhouse gas inventory in many countries. Much of it comes from industry but up to 10% of it is from agriculture.
In South Africa, agricultural methane emissions make up a third of all greenhouse gas emissions, with 11% of those coming from dairy cows.
Scientists and farmers have consequently been experimenting on ways of reducing those emissions. Adding fat or nitrate to animal feed – or feeding cows and other livestock better quality food – has been shown to help.
But organic farmers are often unable to use these methods. This drove researchers at Aarhus University in Denmark to tackle the problem.
Through laboratory research, they have calculated that oregano can have a big effect on the methane emissions from livestock.
Greek oregano, the test species being used in the study, has a high content of essential oils, which reduces the methane produced in cow’s rumen as they digest food.
Kai Grevsen, a senior researcher at the university’s department of food science, said: “The goal is to show that we can reduce methane emissions from dairy cows by up to 25% by adding oregano to the feed.”
The research will continue over the next four years. The milk will be sold on the basis of its “climate-friendliness”, the research team says.
If the tests go well, they will carry out similar tests on conventional livestock, including dairy cows, to complement existing measures.
Grevsen said: “We know that the market for dairy products is characterised by an increasing willingness to pay more for milk with special qualities or values, especially organic, and we hope that in the project we will have a good and balanced dialogue with consumers about the climate and cattle production.”