Livestock in the wastes
Although much of the world is destroyed, civilization still survives the Dark Month, and how could humanity survive without food? And because plants were not a reliable source of food for several years, we had to look towards meat.
Horses
Horses are not eaten, more often than not, the usefulness of horses as a tool for hunting (human and non-human alike), transportation and war outweigh their nutritional value. However, in areas where there is a serious lack of food like Nepal, those who swear by not eating humans eat horses, but they often find themselves being run down by a cannibal on a horse.
Pigs
Pigs are the backbone of the non-cannibalistic human diet, due to their omnivorous diet. As rats and bugs have increased their presence since the dark month, ranchers have used rats and bugs as feed for pigs. As underground farming techniques developed, pigs got a better diet. Wild boars are a menace in the wasteland and some humans use wild boars as companions.
Cows
Cows are also quite important in the wasteland, as they produce milk, a source of calcium, a substance that reinforces the skeleton. Cows have been farmed for a long time likr any other animal on this list, but Cows do not revert to a wild boar-like status after leaving human control. Cows are always found in ranches due to their inability to survive in the wastes, unlike the pigs.
Chickens
Chicken, being flightless small birds do not survive out in the wastes often, being torn down by dogs or cats. Chicken are almost always under human control.
Sheep
Sheep are in a similar situation to the chicken, except that sheep have more or less a timer on their life outside of human control. Their wool can overgrow and the sheep overheat when not sheared. Sheep meat is rarer than pork or beef, but is definetly not rare.