The staple food of your pet chicken is layers mash, or pellets. This contains all the nutrients needed to lay eggs, and treats should not be given before the afternoon, when the chicken has had time to fill up on the mash/pellets. The mash is ground very finely, and can be fed dry, or mixed with water to form a kind of porridge. The pellets are a different form of the same food, so either is fine to feed to your chickens. Pellets are less messy than mash, but it is more interesting for chickens confined to a pen to spend time foraging through the mash. Be careful to keep within the sell by date on the packet.
Organic feed is available for those who prefer it. It is worth considering that bantams may need/prefer a finer grade of pellet due to their small beaks. You can buy the food online, from a poultry supplier or possibly even a pet shop. It is very good value, e.g. £5 for 20kg that will last for a month for 4 chickens! If anyone has the name of a good online supplier, please feel free to add here.
Chickens are omnivores and will eat pretty much anything! Chickens do not overeat, so if you leave a few days food, you can go on holiday for a day or so and they will eat what they need. Legally (see DEFRA website) you are not allowed to feed chickens meat because that is how Foot and Mouth started with pigs, but chickens may eat slugs/snails/worms/small frogs they find on their travels and this is perfectly natural. Some foods such as bread, grass or hay may cause a impacted crop, so it is worth watching out for this. Chickens will nibble on fruit and vegetables, and even plants in your garden. It is worth penning off plants to protect them from the chickens. Surprisingly a chicken will even eat a cooked egg, or raw egg that has been broken in the nest. It is very rare for a chicken to delibrately break and eat an egg. If you buy a new brand of food, you should mix the end of the old food with the new food so that the chickens will eat the new food.
You should only feed treats in the afternoon as the food contains neccessary nutrients for the chicken and for producing eggs. Too many treats can cause a drop in egg production as the chicken fills up on treats and not their staple layers mash/pellets. Your chickens may be a bit fussy about what they like to eat, so you may need to experiment. Your chickens may like grapes, lettuce, cabbage, tomato, cooked pasta or rice, salad, cereal, or corn. This is not an exhaustive list, please feel free to add your own suggestions here. Our chickens really like pearl barley that we can buy for about 40p from the supermarket. Treats can be very useful for training your chickens. Handling, and returning your chickens to the run can be made a whole lot easier with the aid of a tasty treat. Bread must be soaked if fed to chickens so that it does not block their digestive system.
Chickens do not have teeth, but grind their food in an organ called the gizzards in the digestive system. This relies on a supply of grit to grind the food, which the chicken may find whilst free ranging, or you may need to buy. It can also help with forming the eggshell. I now mix grit in with the food as we provided it separately and the chickens just ignored it. A lot of chicken feed does contain some/all of the components of grit like oystershell. Weak eggshells can be caused by lack of calcium, which can be supplemented in the diet, (e.g. add Shellstim to the water) or cheaply produced by heating eggshells in an oven, crushing eggshells finely, and mixing in with the food. Apple cider vinegar is also thought to help with calcium absorption.
Chickens need a fresh supply of water to drink. Chickens can’t swallow, so interestingly drink by throwing their necks back. They will sometimes drink from puddles when they are free ranging.
Garlic powder can be mixed in with the food, or a clove put into the water to act as a natural wormer and to also reduce the smell of droppings. It may make eggs smell garlicky!