The bird has no teeth, food is swallowed whole and goes into the crop where it is stored and mixed with saliva. If you feel the crop you can tell if a bird has been feeding or not.
The feed passes from the crop into the stomach where it mixes with the juices before passing into the roundish, thick walled, muscular organ called the gizzard. The gizzard contains small stones which the bird has eaten to help the gizzard to grind up the food for digestion. Nutrients are absorbed as ground up feed passes along the intestine.
The digestive system of the bird
Birds do not produce liquid urine. Waste from the kidneys forms a thick white material which is mixed with the faeces (droppings). Both are then passed out through the cloaca. The duck produces wetter droppings than the chicken.
What the bird needs in its feed
From hatching (1 day old) to 3 months of age, birds will need feed which contains large amounts of protein for body growth.
When birds are laying eggs minerals are important in producing good eggs.
Birds kept for meat will need a lot of protein in their feed.