It is highly unlikely that the entire world is going to go vegan overnight, and so we won’t have the ‘problem’ of what to do with all the animals in farms. (Although if that did happen, we would have a duty to care for those animals in sanctuaries for the rest of their lives, which would be a wonderful ‘problem’ to have!)
In reality, though, as each of us chooses not to buy animal products, fewer animals will be bred, reared and slaughtered in the future. This is how the supply-and-demand market works. If people don’t buy a product, it will stop being produced. So, if the whole world did eventually go vegan, no more animals would be bred, and farmers would diversify into producing beans, broccoli and beetroot. Since producing vegetables is more labour-intensive than farming animals, there would be more jobs in farming.
Some people worry that individual species of farmed animal would become extinct if people stopped eating them, and for many farmed species this would most definitely be a good thing. Farmed breeds are not natural in that they do not occur in the wild. They were specifically bred by people to have certain physical traits, such as large muscles or high milk yields, but these money-making traits also cause a lot of suffering. Commercial breeds of turkeys and broiler chickens, for example, are bred to put on a lot of weight as quickly as possible and as a result their joints are painful, their hearts are weak and they are prone to bone breakages. It is right that these poor creatures are not bred to be this way. But that doesn’t mean that all poultry breeds – or any other farmed animal species – will completely die out. (Just think of the thousands of species that we do not eat and who survive.) They would need the right habitat, of course, but that would be easier to provide for them as we would need a lot less land for farming.
We understand that people hate waste and worry about the meat on supermarket shelves being thrown away if there was a shift towards eating plant-based foods. Retailers do throw a lot of food away already – both animal- and plant-based – and there are moves to curb this. But there is a waste of life right through the farming cycle: millions of animals die at birth on farms; millions more die during their growth period from disease, injury or by being born into too large a litter. Millions more will be killed as they are simply not useful (male chicks, goats and dairy cows) and millions more die in farm fires, floods or traffic accidents as they are taken to slaughter. The piece of meat you worry about wasting is the tip of an iceberg in terms of lives already wasted. By not buying that piece of meat, you are not condemning all those others to a wasted life, too.
If you choose a veggie burger over a meat burger today, the meat you don’t buy may be sold at a discount as it nears its sell-by date. If you continue to choose the veggie burger, the retailer will soon spot that it is selling fewer meat burgers, and will change its order in favour of veggie ones. That will have a knock-on effect to the farmers who rear animals and they will rear and kill fewer.