I read the column by the League of Women Voter’s article about methane. As usual, the humble bovine receives an undue share of the blame. As a small ruminant veterinarian and former animal science major, I thought I would add some perspective about cattle and methane.
First, a chemistry lesson. Both sucrose and cellulose are made from glucose molecules. The difference is the chemical bond that connects the glucose molecules. Humans can only digest simple sugars like fructose and sucrose. However, the bonds in cellulose can only be broken down by bacteria. The breakdown of cellulose in an anaerobic (without oxygen) environment releases methane. This happens regardless of where the cellulose is broken down. If this happens in a wetland or rice paddy, you get muck. In fact, wetlands produce 30% of the natural methane produced. When cellulose is broken down in a ruminant, you get meat, milk and a plethora of animal products.
Cellulose is the most common biopolymer on the planet, and aside from a minor use as fiber, humans cannot utilize any of it. Animals that have a symbiotic relationship with bacteria, like ruminants and equines, can utilize cellulose as well as simple sugars. For example, in the corn plant, humans can only utilize 50% of the energy in that plant, i.e., the grain. Ruminants like cattle can utilize 100% of that plant and then turn that otherwise unusable cellulose into high quality protein for humans to eat.
When cellulose is introduced into the rumen or the large intestine of a horse or other equine, the bacteria use the cellulose and other nutrients for their own purposes. In doing so, they emit waste products including volatile fatty acids and methane. Ruminants and equines have adapted to use volatile fatty acids for energy. In short, if an animal eats grass or other plants, it will emit methane. This means that not only cattle emit methane. Deer, rabbits, llamas, elephants, sheep, rhinoceroses, antelope, etc. all eat grass or other sources of cellulose and they all emit methane. When vast herds of bison roamed Indiana, they emitted vast clouds of methane. And no one cared.
While grass-fed beef may be more nutritious, is it really better for the environment? When ruminants digest cellulose, they release methane. This is actually a net loss of carbon (the building block of life) for that animal.
When ruminants consume grain, less methane is produced and that animal gets to keep its carbon, causing it to grow faster. We feed grain to cattle because it is cheap and gets animals to market sooner. This means that the animals spend less time standing around and emitting methane.
Plants live, plants die, plants get turned into fertilizer and methane. It is the circle of life and it happens with or without human involvement. Yes, methane is produced by livestock in the production of human food. But getting rid of animal agriculture is not going to get rid of methane production. Animal protein can be a large part of a healthy diet and is not going anywhere anytime soon. If you want to eat less meat, eat less meat. But cattle and other ruminants are not the climate villains they are often made out to be. So when you eat a juicy steak, a sizzling hamburger, a lamb chop or a venison burger, don’t think of your food as contributing to methane production. Think of your meal as produced by amazing animals producing food for humans out of food that would otherwise go to waste.
Darcy L. Clark Crook DVM
New Ross
