Our Cattle's Diet is Imperative to a Sustainable Future

Regions in light grey are currently unsuitable for ruminant livestock, and regions beyond the range of the dataset are shaded dark grey.

Credit: Dr Mark Lee

Researchers at Scotland's Rural College have made an incredible breakthrough in research regarding greenhouse gas emissions, and it's all about our cows' diet. When the words "global warming" are mentioned, the first thought that comes to mind is of the greenhouse gas, carbon dioxide. Though carbon dioxide makes up over 84% of greenhouse gas emissions in the United States, it is not the most effective heat-trapping greenhouse gas. Methane traps nearly 20 times more heat than carbon dioxide, and though it makes up only about 8% of US emissions, that number is expected to rise with the increase in one particular industry: cattle farming.

The cattle industry supplies the world with many desired products including milk, butter, and meat, and the consumption of these products is on the rise all over the world. What do cows have to do with global warming? It all comes down to the way cows digest their food. As cows eat, their four stomach compartments contain bacteria that promotes greenhouse gas formation (methane and carbon dioxide) through fermentation, which is then released by belching. This is key to preventing bloating in cows, but it is where the greenhouse gas emissions in cattle farming stem from. This process accounts for a total of 95% of all methane production in the US during 2004, as referenced from the EPA by this Penn State article, which also outlines the digestion process very well. To reiterate, 95% of the United States' methane emissions come from their cows.

Researchers at Scotland's Rural College (SCUC) have made an important discovery in reducing the amount of methane produced from cattle, and it lies in what the cows are eating. As it turns out, plants grown in warmer climates tend to be hardier, often evolving to endure the climate. These genetic adaptations in plants tend to make them more difficult to digest, and the food spends more time in the digestive track of livestock. This increased digestion time leads to an increase in the formation of methane, as the bacteria in the stomachs' of livestock spend more time breaking it down, and thus the cows emit more gas. It is, in a sense, a vicious cycle, as Dr Mark Lee is quoted calling it in the article. Feeding cattle difficult to digest plants leads to an increase in the production of methane, which in turn contributes to global warming, creating warmer climates, and causes plants to adapt to climate change.

An article by Scientific American talks about the result of plant adaptations from a genetic standpoint, and the difference in life span and ability to adapt accordingly. Plants with shorter life spans that grow faster and produce offspring in quick succession will adapt the fastest to the change in climate, and thus have a higher chance of surviving. This includes many of our crops and livestock feed. These adaptations could result in plants that are more difficult to digest, and may, ultimately, produce more methane from cattle. Therefore, it is important to look at what is being fed to cattle now, so as to limit the impact of climate change on their diet going forward. Constructing a diet of nutritious, easily digestible foods for our livestock is imperative in reducing greenhouse gas emissions from an industry that is only expected to expand over the next decade.