The role of light in the chickens’ world
How is it possible that chickens can see better than humans?
After a number of studies, it has been found that chickens can see much better than humans at low light intensity, especially they can perceive more colours.
This is because humans have three types of light-sensitive cones – red, blue and yellow. A chicken, on the other hand, has additional cones that are sensitive to violet light and are separately specialized for perceiving movement. Birds are thought to need these for foraging and probably also for mating. Because of their sensitivity to ultraviolet light, they perceive dawn earlier than we do, which means that chickens see daylight almost an hour earlier than we humans do. However, they cannot see at night because they lack nerve cells that respond to light intensity. They also see less well from a distance of 25-50 meters, which explains why they do not move further away from the chicken coop, but keep a safe distance.
Of all the senses that birds use, the sense of sight plays the most important role, while the other senses are less developed. It is also worth noting that birds’ eyes are proportionally larger than those of humans. Their size is about 15 % of the weight of the head, while the ratio in humans is only a little more than 1 %. Nevertheless, the colours a bird sees are not the same as those of humans, as they are more sensitive to long-wave colours and less sensitive to short-wave ones. In the end, it turns out that a bird can only distinguish 20 colours, whereas a human can distinguish 160.
How does light affect the chickens’ functioning?
Light has a decisive influence on the rhythm of life of chickens, it regulates the internal clock and controls the sleep rhythm as well as the activity and rest phases and the feeding behaviour. Chickens are indeed among the animals that react strongly to light. It directly stimulates the animals’ endocrine system and influences the maximum use of the laying hens’ production potential. In addition, the right lighting stimulates feed intake – if there is insufficient light or if the light day is too short, the birds take in less feed than they need, which leads to a drop in production output. We must not forget that the length of the daytime and the intensity of the lighting in the poultry house are factors that directly affect the hens’ laying performance. These parameters are particularly important in autumn and winter (in December, for example, the astronomical day is less than eight hours long). Chickens need at least 14 hours of light a day. The low angle of incidence of the sun’s rays on the ground and the heavy cloud cover, which blocks much of the light in our direction, further complicate the situation during this period. To maintain a satisfactory laying performance of the flock, it is therefore necessary to use artificial lighting.
What is the so called lighting programme?
The lighting programme determines the starting phase of the laying hens and influences their productivity during production. By setting the lighting programme correctly, productivity can be adapted to the specific needs of the farm (of course it also has its limits).
However, the lighting programme actually starts with the first day of the hen’s life, when the length of the daylight is generally 16 to 24 hours. It is then gradually reduced to 8 or 10 hours until the hen is 10 weeks old. At 17 or 18 weeks of age, the hens’ day length is gradually increased to promote maturity. Subsequently, at 22-24 weeks of age, the hens’ day length should be increased to at least 14 hours.
The most important thing is that the laying hen farmer continues the light programme to which the birds have become accustomed so far. In this way, a too early start of egg laying can be prevented.
It is worth paying special attention to this, because if this process starts too early, the hens will not take in enough feed to develop properly at the same time.
It is therefore very important to get all the necessary information from the breeder of the pullets.
The light or lack of light affects the temperature and humidity of the environment in which the chickens are housed. In order for them to have sufficient natural light, they must have a run or provide the room with large enough windows. Natural light is an excellent source of vitamin D. In addition, light with its UV rays has a germicidal effect.
Insufficient lighting can lead to misbehaviour (aggression, feather pecking, cannibalism, self-mutilation, malnutrition), disease and even death.
As you can see, light, especially daylight, is not only important, but it is simply indispensable for the animals, as it has a significant influence on their functioning. It is therefore necessary to choose a chicken coop that is adapted to the needs of the chickens and that really lets in a lot of sunlight. It is worth paying attention to this, because it is not always possible to have an all-day outdoor run – either because of the weather or because of legal regulations that restrict the chickens’ run in certain situations. When deciding whether to keep chickens in a standard or mobile coop, it is therefore good to pay attention to the key word “light”. Apart from the fact that this is essential for the chickens, working in a darkened poultry house is not pleasant for humans.
