Animals need to eat. That much should be obvious. What’s not as intuitive is the idea that what we’re feeding our livestock does more damage than all the other impacts I’ve discussed (with the possible exception of deforestation). If you were starting to think everything was just cows fault then this is where pigs and chickens catch up too - relying almost solely on feed. Vaclav Smil, Distinguished Professor of Environmental Science, argues:
That’s quite the claim.
To understand why feed has such an impact we must look at basic biology and physics. These animals are not growing out of thin air: they need to eat and, no matter how efficient we make the process, some energy is going to be lost. Try as you might, animals are going to waste energy moving, growing inedible organs, or something equally selfish. That means that we are forced to put more energy into feeding them than we get out in meat.
In 2010, 500 million tonnes of feed was consumed by livestock. Across the world approximately one third of the overall agricultural land goes towards growing feed for animals. No matter how you try and spin it it’s going to be much more efficient to grow crops to make bread or pasta instead, even including per calorie estimations (i.e. more calorific food may have a lower impact per calorie even though it's overall impact is higher than other lower calorie food).
One of the major criticisms of meat-based diets is that we’re feeding these animals things we could eat ourselves. The leading feed products are corn-based and soybean based. When millions of people in the world lack sufficient food to eat, this can appear to be indefensible(1). What’s more, all the negative impacts we have from growing food are going towards animals that have their own negative impacts,