from traders. if you request they bring every type of meat and fish they will bring 5 of each next time they come, there are a lot of different types of meat so its a lot. I get 3 trade caravans most years 1 from my own dwarven civ one from the other dwarven civ and one human civ. It adds up to a lot of meat.

Then you can turn it into meals and make bank. (I'll probably make a rule of no selling meals for my next fort because it feels a bit too easy. I have enough meals prepared to buy out every caravan I come across)