When you've got not fridge and the environment isn't always condusive to curing and preserving meat, it's very handy to raise an animal that's a smaller amount of meat (say one meal) than something like a goat, pig, chicken or cow.
They breed easily and rapidly, eat scraps and vegetation that humans normally don't. So folks keep a herd of Guinea pigs and just slaughter whatever they need for a meal.
It's very clever and much more environmentally friendly than clearing forest for larger animals.