Okay, first of all – NO! Chickens do not have teeth. They eat with the beak. This is the perfect tool for pecking feed in crumble or pellet form, small grains, grass or insects – sometimes a mouse! Their mouth contains glands that secrete saliva, which wets the feed to make it easier to swallow. Chickens use their tongue to push the feed to the back of the mouth to be swallowed.
So do they swallow everything whole? Well, sort of.
Once they consume their feed, their oesophagus takes the food down to the crop (a pouch in the oesophagus used to store food temporarily before moving it on to the stomach) to be stored. Not long after a chicken has eaten, the crop will feel full and bulge. You may notice a lump on the side of your chickens or chicks neck. This is generally just a full crop!
Food from the crop then slowly passes down to the stomach (proventriculus). The proventriculus mixes the food with acids and digestive enzymes. Food is then passed through to the gizzard, where insoluble grit has accumulated. This grit may contain small, hard particles of pebbles or sand. Grit gradually wears down in the gizzard, so birds need to occasionally swallow new stones. Food is then ground down by extremely strong muscular action, combined with the grit in the gizzard. The gizzard essentially works as the chickens teeth!
After being thoroughly ground up, food passes into the small intestine where it takes in essential nutrients. A chicken’s liver then uses bile to break down carbohydrates, fats and proteins for use in their body. Next, the large intestine absorbs water and removes unnecessary waste products.
What is left then passes through the ceca (two blind pouches located where the small and large intestines join), the large intestine (colon), the cloaca and is finally excreted via the vent (a chickens bottom!).
Interestingly, chickens don’t pee, and they don’t have a bladder. Urinary system wastes (urates is the word used for bird urine) produced by the kidneys are simply dumped in with the digestive wastes at the end of the digestive system, at the cloaca, or vent. That’s why normal chicken droppings contain white urates mixed with darker digested material.
Aren’t our feathered friends fascinating?