"Milkbag" is the nickname for female fluffy ponies that are solely dedicated for producing milk to countless foals within shady, large-scale breeding mills. Most of them are created from dams that have had multiple miscarriages, but when there is a shortage, even perfectly fine fluffy pony mothers are turned into milkbags. Their diet consists of hormones and protein that causes their teats to swell in size and produce large amounts of milk. They consider any foal that they do not recognize as their own to be a "bad babbeh" stealing away milk meant for their own progeny, and desperately try to chase away or harm the perceived thieves. Thus, in order to ensure the safety of the hungry foals, the milkbags' limbs are amputated so they won't struggle, walk away or harm the foals. To further reduce their mobility, milkbags are sometimes suspended in the air via a harness or barred against a wall so that the foals can drink in peace. To stop mares from whining (as a milkbag's life is naturally miserable) or trying to bond again with their original offspring, they are usually blindfolded and muffled. In the more extreme cases their eyelids are sewed together and their tongue surgically removed.
The 'lucky' milkbags at the more humane breeding factories that don't always make use of amputation, muffles, blindfolds or harnesses, put tranquilizers in the mares' original diet that keep them in a deep sleep, sparing them the awareness of their torment. There are two main methods to deal with milkbag excrement. The first is to insert suction tubes into the anus and vulva. The other is to keep the milkbags' rears over a drain that leads to a sewer. As the milk production of these fluffies is artificially induced via hormones, it is possible for male milkbags to exist as well. This is, however, extremely rare.