Light intensity management and relation with liveability

Light intensity during the rearing period

Light intensity is important during the first days of the rearing period in order to encourage the activity of the chicks to discover their environment and to find very quickly the water and the feed.

Therefore, this light intensity can be reduced progressively. The ideal light intensity will be determined in practice by the following needs:
- Light required to inspect the birds
- The degree of darkness of the building (light leaking in)
- The intensity to be used during the laying period

In dark house, (Houses where the light penetration from outside doesn’t exceed 0.5 lux.)
- The light intensity required is very low. The ideal light intensity is the minimum needed to get a good inspection of the flock. An intensity of 5 to 10 lux is sufficient.

In semi dark house or naturally lit houses,
- Houses where the light penetration from outside exceeds 0.5 lux), the light intensity should be adapted to the degree of darkness of the house to avoid any interference with the light stimulation.
- Artificial light intensity should be, if possible, 12 times the light intensity coming from outside. If the difference is not big enough, birds will consider the day length as the natural day length and not the artificial day length if the artificial duration of light is shorter than the natural day length.

Influence of intensity experienced during the rearing period,
- Naturally lit houses, free range and organic production systems, barn system of production asking for part of natural light.
- When the production period is in naturally lit houses, an intensity of 40 lux is needed to avoid too much of an increase in intensity on transfer to the laying house, which can lead to nervousness and pecking.

Light intensity in production

The light intensity required is low. No significant differences have been found in the different trials with today’s breeds. But as stated for rearing period, we encourage increase in light intensity for a few days from transfer time in order to help the bird to discover its new environment and to find easily water and feed systems.

Thereafter, the light intensity could be reduced step by step to a minimum of 0.5 lux at the feeder level in the dimmest areas of the laying house if during the rearing stage light intensity doesn’t exceed 10 lux.

There is a strong relation between bird activity, stocking and feather loss during production.

Light intensity and liveability

Recent investigations have demonstrated a strong relationship between light intensity, physical activity and feather loss. High light intensity results in increased mortality as a result of vent pecking, which is increased with feather loss.

High intensity tends to increase the nervousness of the birds and pecking (Hughes 1972 and Savory 1995). The activity of the bird is also influenced by the source of light. The increase in the number of tiers in recent cage installations, together with the change from incandescent bulbs to fluorescent tubes or to fluorescent bulbs, has resulted in an important increase in light intensity to birds in close proximity to the light source.

High lights intensity results also in a higher feed conversion ratio. When light intensity is reduced by 50%, the feed saving will be about 1.6g.

Mortality and activity
- In battery cages, we sometimes find considerable differences in light intensity at different levels. The birds close to the light source demonstrate a more important activity leading to more risks of pecking and mortality.
- Control of the mortality per tier could lead to different level of mortality as the following



Mortality and light source
- In battery, the activity has been measured in one experiment led by Boshouwers showing that activity is much more important by using fluorescent light and is strongly correlated to the light intensity. Birds are sensitive to fluorescent light, which they see as scintillating rapidly.



F = Fluorescent Lighting I= Incandescent Lighting

Practical advises
- As shown herewith, the light intensity required is low.

Effect of light intensity of performance



- It is most important to have the most uniform distribution of light as possible. The distribution of many bulbs arranged in quincunx form in the new large laying units with several tiers.
- Existing arrangements can be improved by using shades or adhesive tape on the bulbs to reduce the intensity for those birds situated in front of the bulbs. Red or warm light seems to be useful for reducing activity, feather loss and pecking.

Before any modifications are made, it is extremely important to measure the light intensity at various points. The reduction of light intensity, we have to be certain that the least well illuminated area has a light intensity of 0.5 to 1 lux. This control of light intensity will help to improve the feed conversion ratio. This energy use increases by 1 Kcal/hour/bird when the intensity goes from 1 to 10 lux and also from 10 to 100 lux. This is equal to a little more than 5 g of feed between 1 and 10 lux and nearly 11 g of feed between 1 and 100 lux (Boshouwers 1993).