I've been looking for accurate statistics for the number of farm animals for a while, and this page seems to have them. I didn't know that for every one of the 7 billion people on the planet there are almost 3 chickens, 19 billion in total. Chickens are better converters of animal feed (maize and soya) than other farm animals, perhaps especially when they are used for egg production.
There are 1.4 billion cattle. Cattle can eat grass that we can't eat, and some areas can't be used to grow crops but produce grass. Many cattle, perhaps the majority these days, are kept in feed lots and fed animal feed. There are 1 billion sheep. As far as I know sheep only eat grass although they might get a supplement of feed.
There are 1 billion pigs on the planet. They are not efficient converters of animal feed like chickens, neither can they eat grass like cattle and sheep can. Traditionally, pigs were fed on food that we can't eat, waste food or stale food. Nearly all pigs today are fed on a high-calorie high-protein diet consisting mostly of maize and soya. Pigs are about the same size as us, and I think they are the best example of how crops are being wasted by being fed to farm animals.
A billion is a big number. If you think about the entire population of North America, Central America, the Caribbean and South America combined, that doesn't come to a billion. If you think about the 6 giant cities in the Americas, each of which is bigger than any city in Europe, it makes you think. The global population of pigs is bigger than the entire human population of the Americas.
Of course we do end up eating the pigs, and they do sometimes eat what we would not want to. Nobody would want to eat pig food, but people have been eating maize and soya for thousands of years and enjoying it, along with wheat, barley and fish. Fish, especially anchovies, form part of animal feed. This is no way to feed the world.
According to the Economist site, in China there are 0.35 pigs per person. So for every 3 people there's a pig. No wonder they have to import grain. That's 451,000,000 pigs. In Denmark there are 2.24 pigs for every person, the only country where there are more pigs than people. There is no geographical reason why this should be so. Denmark is nowhere near where maize and soya are produced. You could understand it if countries like America, Brazil or Argentina had that ratio of pigs to people. I imagine vast fleets of ships carrying animal feed from the eastern coasts of North and South America to northern Europe. It seems a strange way of doing things, but then the global agricultural system has never made much sense.
Imagine a maize and soya farm in Brazil. Imagine if most of the maize and soya was exported to feed people, but some of it kept on the farm to feed a relatively small number of free-range pigs. Pig slurry was put back onto the land. The pigs could be slaughtered on site. Livers could be frozen and exported. Ham and bacon could be made on site providing employment and exported. Seems sensible to me, so sensible that you kind of know that nothing like this happens or will ever happen.
Instead we have pigs, one of the most intelligent animals, kept in horrible conditions. Slurry that can't be disposed of. New viruses and antibiotic resistant bacteria breeding away. One eighth of the world's population starving while an equal number grow fat. It's crazy, and no amount of GM technology or badger killing is going to make it better.