General principles of the lighting programmes during laying period

In the production as well as the rearing periods, the lighting programme greatly influences the feed consumption. In addition, during all its life, a chicken remains sensitive to changes in the duration of illumination.

The objective of the lighting programmes during production period is:

- to encourage growth at start of lay
- to counteract the harmful effects of decreases in natural day length
- to control the liveability through the light intensity management
- to improve egg shell quality

Other lighting programmes can also be introduced during the production period to adapt the egg weight to market demand, to improve egg shell quality or to control feed intake for some breeds.

Chickens sensibility to change of illumination

First at all, the lighting programme in production should be the continuation of the lighting programme used during the rearing period. We have to make sure that the light duration in production house is as long as the light duration the birds experienced the last day before transfer.

As chickens remain sensitive to decrease of light duration during all the production cycle, the day length (the interval between lights on and lights out) should not be decreased during lay.

- A day length of longer than 16 hours is not necessary in dark buildings.

- In naturally lit or semi-dark buildings, one should always avoid a decrease in the day length during lay by maintaining, during decreasing natural day length, a day length which is equal to that of the longest natural day experienced, by making “lights on” and lights out” coincide with the times of sunrise and sunset

Lighting programmes at start of lay: 15 hours at 50 % production

From 17 weeks till peak of lay, feed consumption has to increase by 40 to 50 % according to rearing systems of production to cover requirements for growth, peak of production and increase in egg weight at start of lay.

- 350 g of growth between 18 and 28 weeks old
- from 0 to 58 g of daily egg mass produced at peak of production

The amount of feed eaten is dependent on the day length. A change in day length of one hour changes feed intake by about 1.5 to 2 g.

We recommend to adapting the increase of light duration at start of lay to get at least 15 hours of light at 50 % production to encourage increase in feed intake. For all the birds, production is determined by the amount of food intake at start of lay. The introduction of 1h30 or 2h00 of light could also be associated at the same time.

1h30 to 2h00 light in the middle of the night

This technique is widely used. It encourages feed consumption and growth at start of lay. This introduction of 1h30 or 2h00 of lights doesn’t interfere with the normal lighting programme. This programme can be introduced when we want at start of lay (usually from 5 % of lay) and discontinued at any time without affecting the production. The bird doesn’t perceive the stop of this programme as a reduction of light duration.

Principle of the technique:

- The lights should be switched on about 3 hours after "lights out". It can be discontinued at about 30 weeks of age if bodyweight and feed consumption are on target.

- It could be maintained during all the laying period.

- When it is discontinued at 30 weeks, it could be introduced again at 45 weeks old to reduce the deterioration of the shell quality (and colour) at end of lay. Introduction at end of lay is not to increase feed intake but to give the possibility to the chickens to eat limestone (Calcium) during the shell formation.

- In a hot climate or during a hot spell, lighting during the middle of the night reduces the ill effects of heat by encouraging feed intake during cooler conditions.

- If it's possible, we advise giving feed distribution a short time after the lights come on.

The influence of a 2 hours light interval during the night



Cyclical lighting programmes

These programmes can only be used in buildings, which are totally light proof. The 24 hours of the day are split into cycles of 2, 4, 6 or 8 hours. Each cycle is made up of a period of light and a period of dark. The length of light in each cycle can be varied during the laying season.

These segmented lighting programmes are well known for their positive effects on:

- Egg shell colour and egg shell strength
- Egg weight
- Control of red mite population
- Liveability and FCR management

The physiological effects of such programmes are as follows: oviposition is desynchronised and laying is spread out over 24 hours. The length of time taken to form an egg is increased. This could allow an increase in egg weight by 2-3% but reduces the number of eggs laid by about the same proportion.

In practice:

- They can be used any time throughout lay, including the early stages if it is economically useful to get a higher egg weight.

- When starting to use one of these programmes, we advise keeping the same total hours of light per day for several weeks.

- According to evolution of the feed consumption, a progressive increase of each dark period is possible. This reduction of total light duration doesn’t affect the production but reduce activity (improve liveability) and save feed.

- These programmes assist in reducing red mite by encouraging preening and delousing.

The practical implementation: progressively according to age and consumption



- The reduction of light duration must be done progressively according to the water and feed consumption observed. It is possible to reduce total light duration to 9 hours in a progressive way.

- If feed consumption decreases too much and lasts several days after a change of pattern, then go back to the previous lighting programme (increase light).