Chickens are birds that lay large numbers of eggs. We know chickens from the farm or from the store. There we buy chickens to eat. In Germany, we tend to speak of chicken, in Austria of chicken. In Switzerland, we need the French name Poulet. We also find boxes with chicken eggs on the shelves.
We talk about chickens in everyday life. In biology, there are the order Galliformes. These include the following species: partridge, quail, turkey, capercaillie, pheasant, peacock, and domestic fowl. When we talk about chickens, we always mean domestic chickens.
In agriculture, domestic fowl is counted among the poultry. The male is called a rooster or rooster. The female is the hen. When it has young, it is called a mother hen. The young are called chicks.
Bantams weigh about half a kilogram, other chickens reach over five kilograms. The roosters are always slightly heavier than the hens. Chickens wear feathers like all bird species. However, they can only fly poorly and mostly remain on the ground.
Where does the domestic chicken come from?
The domestic chicken is the most common pet of people. In the world, there are an average of three chickens for every human being. Our chickens are bred from Bankiva chickens.
The Bankiva chicken is a wild chicken native to Southeast Asia. Breeding means that people have always needed the best chickens to make youngsters. Either these are the chickens that lay the most or the largest eggs. Or then the chickens, which get fat the fastest. But you can also breed the healthiest chickens. This is how the different races came about.
How do domestic chickens live?
When chickens live free on a farm, they eat grass, grains, worms, snails, insects, and even mice. Chickens also swallow some rocks. As the muscles around the stomach contract in rhythm, the stones grind the food.
They live freely in groups. Such a group always has only one rooster and many hens. There is a strict hierarchy among the hens. It’s called the pecking order because the animals sometimes peck at each other with their beaks. The highest-ranked chicken gets to sleep on the top perch and pick the best feed. That’s why you have to spread chicken feed widely so that there are fewer fights.
However, the single group of chickens on the farm is becoming increasingly rare. Most chickens come from huge farms. Free-range chickens live best. So you have daily outdoor exercise. In the middle are the chickens in barn housing. They live on the floor of a hall. Caging is the most unnatural. The chickens just sit on bars or even on the bottom of the cage.
What are the different types of domestic chickens?
Breeding chickens are kept for their offspring. Hen and rooster are therefore carefully selected and combined. Domestic chicken is a breeding chicken, but there are many different breeds. This depends on whether meat or eggs are to be produced. Breeding chickens live no differently than laying hens or broilers. Due to the one-sided breeding, there are also many sick and weak animals that are no longer used.
The laying hens were bred to lay as many eggs as possible. In 1950, a good laying hen managed to lay about 120 eggs a year. In 2015 there were about 300 eggs. This equates to six eggs a week. They start laying eggs 20 weeks after hatching. After about 60 weeks they are killed because the eggs are getting fewer and worse. That no longer pays off for the chicken farmer.
The broilers should get fat as quickly as possible so that they can be prepared in the kitchen after slaughter. Roosters and hens are used for chicken dishes. In Germany, they are called Hähnchen, in Austria Hendl, and in Switzerland Poulet. Chickens for fattening are slaughtered after 4 to 6 weeks. They are then one and a half or two and a half kilograms.
How do domestic chickens reproduce?
The hens let the roosters know when they are ready to mate. The hen crouches and flaps her tail feathers up. The rooster mounts the hen from behind. The rooster then presses his orifice onto the hens. Then his semen drips out. The sperm cells find their way to the egg cells themselves. The sperm cells can live there for up to 12 days and fertilize egg cells.
The germinal disc is formed from the fertilized egg cell. From this, the chick develops. It takes the egg yolk with it as food. It is also called yolk. This is wrapped in a kind of skin, like candy in its paper.
The embryonic disk sits on top of this transparent skin. The albumen or albumen is around the outside. The hard shell follows on the outside. Anyone who cracks an uncooked egg can see the embryonic disc on the transparent skin around the yolk.
It takes only 24 hours from fertilization until the hen lays her egg. Then the next egg gets ready. She is fertilized from the supply of sperm cells. If the hen lives without the rooster, or if the supply of sperm cells is exhausted, eggs will still develop. You can eat them, but they don’t produce chicks.
The hen has to incubate the laid egg for 21 days. This can also be done in an incubator with artificial heat. During this time, the embryonic disc develops into a finished chick. A small point has grown on its beak, the hump. With this, the chick hits the eggshell and makes a notch all around. Then it pushes the two halves apart with its wings.
Chickens are precocial. They quickly stand on their feet and go foraging with their mother. So they don’t need to be fed by their parents like many other birds. The hen protects her chicks and leads them to water and good feeding places. The rooster does not care about his offspring.