The key to cutting emissions from cattle? Make cows more efficient

Cows are one of the biggest contributors to climate change, responsible for about 14.5% of total man-made greenhouse gas (GHG) emissions, and are very much in the sights of environmental campaigners.

The obvious solution? Simply eat less meat, in particular beef - indeed there has been a huge increase in the number of people who are going partly or entirely vegetarian or vegan. However, the vast majority of people will continue to eat meat and dairy, so reducing the industry's impacts is a crucial way forward.

There are unfortunately a number of layers to the problem, however. Cows produce methane when they digest their food and storing manure in liquid form also produces methane emissions. Meanwhile nitrous oxide, another greenhouse gas, is produced when growing animal feed and in manure. Emissions are increased further if forests are cut down to grow animal feed and graze cattle. Another, equally pressing, problem is the huge amount of water needed to produce beef - 15,000 litres per kg.

The simple solution

There are some obvious first steps that the industry can take, such as using existing land more efficiently to prevent forests from being cut down to grow cattle feed. There is also huge potential to use manure, both to produce biogas using the well-established technique of anaerobic digestion, and as a natural fertiliser. Making artificial fertiliser produces a lot of emissions, as does transporting and applying it.

The problem does not just lie in industry - if we all ate all of the food we bought, instead of wasting a third of it, the entire food system would be significantly more efficient and we could cut GHG emissions by a total of around 70 billion tons, about twice the amount that is emitted globally every year.

Systemic improvements

The United Nations' Food and Agriculture Organization (FAO) says that farmers can cut emissions by 20-30% simply by getting more meat or milk from each animal. “Helping farmers to increase the productivity of livestock is a means to improve rural livelihoods and food security. It also supports better resilience to climate change," the FAO says.

There are three key ways to improve productivity, the FAO adds – improving the quality of animal feed; improving animal health and husbandry so cows can produce more calves and fewer animals are affected by diseases, parasites and insects; and breeding to increase productivity by improving traits such as the amount of weight calves gain as they grow. Breeding can also make livestock more resilient to changing environments, and more resistant to stress or shocks and diseases.

Focus on soil and health

Improving soil health is vital. Grasslands around the world store around 343 billion tonnes of carbon, nearly 50% more than forests, the FAO says, so they are a habitat that has a key role in sequestering carbon and thus limiting the impacts of climate change. But their ability to do this is under threat from the growth in the livestock sector and poor grazing management.

There are a number of ways farmers can restore the quality of pastures and increase the amount of carbon stored in soil. Some farmers and researchers believe that rearing livestock can actually help to cut emissions by improving soil health to allow it to take CO2 out of the atmosphere.

This technique, known as mob-grazing, involves getting livestock to mimic the way that cows and sheep would feed in nature, when they would move around regularly as a herd, finding fresh grass to eat and then moving on to the next patch of grass. The theory is that farmed animals overgraze fields when left in them for long periods of time, forcing farmers to use fertilisers to replace nutrients and add grain to their cattle's diet. Growing grain for animal feed further contributes to GHG emissions through land clearance.

By giving cattle access to a small field or patch of grass for one day, then moving them on to another area and allowing each area a long period of time to recover, no one field will be over-grazed, making the grass healthier and reducing the need for fertilisers. At the same time, the healthier grass grows more and retains more CO2.

However, this will not be enough on its own. The University of Oxford's Food Climate Research Network concluded that “while grazing of grass-fed animals can boost the sequestration of carbon in some locally specific circumstances, that effect is time-limited, reversible, and at the global level, substantially outweighed by the greenhouse gas emissions they generate".