Treadle feeders are the gold standard of chicken feeders. They have a step or treadle for the bird to step on that lifts or pushes back a door that covers the feed tray. That prevents vermin from stealing the feed and prevents the flock from soiling the feed. They are also the most expensive feeder but the value they bring in feed savings and sanitation brings a quick payback.
Gravity fed feeders are similar to the treadle feeders in that gravity is used to push the feed down to the feed tray. They don’t have treadles or doors so the cost will be lower but the cost is that the ability to keep the feed protected is much lower. Without a door the birds can soil the feed and vermin can steal the feed. They are used most often in a new flock where rats aren’t a problem yet.
Hanging feeders also use gravity to move the feed down to the to the feeding tray but instead the feeders are suspended from the ceiling which offers a small amount of protection from soiling from the chickens and feed theft by vermin. Hanging feeders are usually the first attempt that a flock owner will take to try to protect their feed from soiling and vermin theft.
Trough feeders are generally used for chicks or in industrial flocks where vermin are controlled professionally. They are the perfect solution for chicks as the amount of feed isn’t as great due to the size of the chicks and nearly zero risk of vermin stealing feed. Chicks are going to soil the food, that’s a given but affordable given the short time a chick will spend using a trough style feeder.