It is a well-known and well-documented fact that global warming is in part caused by cows and other ruminants. Through digestion, they produce methane, a gas that is 24 times more powerful than CO2 in terms of greenhouse effect. As a matter of fact, cow gas emissions account for a large part of agriculture’s contribution to climate change (agriculture produces 36% of total greenhouse gas emissions). Yet cows are key to the human diet, as they provide meat, milk and, indirectly, dairy products. With the growing world population and increasing numbers of people rising out of poverty, leading them to adopt diets that are richer in animal proteins, the contribution of cows to the deterioration of our environment poses a serious challenge. In the United States, the recent deployment of a plan to fight global warming has generated a surge of ideas to address the issue, with scientists dreaming of designing the clean cow of the future. And it might not be as futuristic as it sounds…
Genetic selection, vaccines and feed
There are two main ways to tackle the methane problem. The first one is to collect and use the gas as an energy source.
In Argentina, where there are more cows than people and ruminants are responsible for 35% of the country’s greenhouse gas emissions,
scientists from the National Institute of Beef Industry have designed a sort of “backpack” that uses tubes directly connected to the animal’s gut to collect the methane before it comes out. It is then converted into energy. A cow produces 300 litres of methane per day, which can power a 100-litre refrigerator for the same amount of time. Methane from manure can also be collected and converted into a gas that the local populations use to heat and light their homes, thanks to individual biodigesters.
But of course, the main challenge is to curb the methane emissions, while producing more meat and more milk to sustain the world population’s needs. Ideas abound in this area. Genetic selection could be one option, since it has been found that some animals naturally discharge less methane because their gut processes food more effectively. This means that the same amount of food can be produced for the same level of emissions. In this case, productivity and environmental protection walk hand in hand, and could encourage the selection of some species over others. In Asia, Australia and New-Zealand, researchers are going down the vaccine track: the idea is to design a vaccine that would be injected into cows immediately after birth to target the microbes responsible for methane production. But for now, the tested vaccines have not proven very effective.
The most promising lead is in fact the least futuristic one: modifying the animals’ diet. Giving the cows more easily digestible feed and plants could dramatically decrease their methane emissions. Diets that include more lipids, through linen for instance, decrease gas production by 10 to 25% while enriching the milk and meat with omega 3. Other plants as well as feed supplements made from plant extracts and probiotics are also being tested. The idea is to find foods that contain molecules with a direct impact on the microbes that produce methane inside the cow’s gut.
But all of these solutions will have to prove cost-effective for farmers before they can be widely implemented. This emphasises the responsibility of consumers: by choosing products made according to these principles (for instance, products from cows in France that have been fed linen hold the Bleu-Blanc-Coeur label), they are financially encouraging change.
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