A finite number of animal species a suitable for life on a traditional farm. Humans, of course, are needed, since they do most of the work, which is to define “work” as efforts that profit humans. Sheep and goat are nice, bred for their milk and wool, and appreciated for their meat. Cows for milk, meat, and leather. Pigs for ham and bacon. Chicken for eggs and meat. Other birds: ducks, geese, turkeys, pigeons, ostriches, emus, pheasant, partridge, peafowl, quail, guineafowl, and swan. Rabbits and maybe guinea pigs for their meat, and maybe fur. Horses for herding cattle. Donkeys, mules, and oxen for pulling or carrying loads. More rarely llama, alpaca, camel, yak, water buffalo, bison, zebu, and muskox. Some animals such as mink and fox, have their own farms. Only a few other animals, such as reindeer, mice, and rats, have been domesticated, but don’t live on farms. Also, farm animals are not pets, except for cats and dogs.