It’s worthwhile getting a basic understanding of how chickens consume food. This can be worthwhile to try to identify problems and to understand why we provide them with grit.
Roughly analogous to our mouths, this is how the chicken gets food into her body. A number of the things we do with our teeth can’t be done by chickens, since they don’t have teeth.
They need to peck at things instead of being able to bite them. You’ll see chickens working quickly, both to get smaller morsels into their bodies and to break up large pieces by trying to pull off more manageable bits of it.
Once they’ve swallowed the food, it goes down their throat towards their crop.
A crop, which humans don’t have, is basically a holding area for food until it moves into the gizzard. Birds with crops will occasionally gorge, filling their crop until it bulges, at which point they may get sleepy and work on digesting what they’ve already consumed.
The gizzard is also distinct from human anatomy. As part of the chicken’s stomach, the gizzard uses small pebbles that the chicken has swallowed to break apart larger pieces of food – what we would normally do with our teeth.
Muscles in the gizzard use these swallowed pebbles to grind food. Once the swallowed pieces of rock – also known as grit – is smoothed, the chicken will excrete or regurgitate them.
If chickens don’t have access to grit, they can have digestive difficulties, leading to health problems.
Chickens also have stomach acids and digestive enzymes in their stomach, much like humans.
Intestine, Pancreas, Kidneys, and Liver
The intestine and liver, along with the pancreas and kidneys work the same way they do in humans. One the food is mashed up and dissolved as much as the stomach (with the gizzard) can manage, the intestines then work to pull as many nutrients as they can out of the mush. These are processed further, such as the liver breaks down toxins and proteins.
The intestine also regulates the amount of water in the chicken’s system.
Waste products from bodily functions are also dumped back into the intestine as it gets close to the end (and as much good stuff has been taken out as possible).
The cloaca is a big difference in birds compared to humans. Basically, birds lack a bladder and don’t pee, instead just having it dumped in with the other waste, and everything gets expelled through the cloaca – an opening at the chicken’s rear end.
Some people believe that birds have no control over their bowel movements, but in fact, they do. In order to lighten their weight for flight, they frequently eliminate waste, with budgies defecating 40 to 50 times a day. Chickens’ frequent defecation means it’s going to go pretty much everywhere. Our chickens go in their coop, throughout their run, and in their food and water. The one place they seem to respect is their dust bath.
The cloaca is also the reproductive opening for chickens, both for mating and laying eggs. All the reproductive organs are inside, and when they mate the rooster presses his cloaca up against the hens in what is called the “cloaca kiss”. Sperm travels from his cloaca into the hen.
For any biologists reading, is this pretty close to correct or did I get anything wrong?