Lighting

The use of a light programme:

	aids a good growth rate during rearing
	assists in the control of the age of sexual maturity
	eliminates large increases of light duration and intensity at transfer

In naturally lit houses, it is essential that the light programme is adapted to the day length that the birds will receive after transfer. A large change in light duration or intensity may cause an increase in pecking. To eliminate this, the intensity during rearing should be slightly raised (30-40 lux).

CONTROL OF SEXUAL MATURITY

Eggs produced in deep litter floor houses are generally smaller than those from cages. To offset this effect you should delay sexual maturity by one week.

Light programmes are designed to control sexual maturity. The programmes advised are designed to reach 50 % of lay at 21 weeks. Light duration should not be increased before the pullets have reached 1450 g.

Several types of programme can be used according to house type (natural, dark, half dark). In addition, according to the target age of P.O.L, the light stimulation can be early or late.

RULES TO RESPECT

Whatever the type of house (natural light or dark) two rules must be respected:

	Never increase light duration between 8 weeks and 1450 g (17 weeks)
	Never decrease light duration after beginning of lay

PRODUCTION IN LIGHT HOUSES

To avoid too great an increase in intensity at transfer you should maintain a higher intensity during rearing.

Too early a transfer can accelerate sexual maturity before correct bodyweight has been reached. Where birds are to transferred early:

	to have the correct bodyweight
	laying house darkened to reduce light stimulation use screens, dark ceiling painted windows
	maintain high light intensity in rearing house
	use a light duration between 6-17 weeks which takes into account the light duration at time of transfer.

After early transfer it is essential to achieve correct bodyweight (appetite stimulation) and to darken the laying house to reduce light stimulation.

In production there is no need to exceed 15 h per 24 h cycle in winter. However, where day length is naturally declining hold light duration at least at the duration of the longest day experienced. When the birds have been subject to increasing natural day length it is important to fix light duration clocks so that for the rest of their productive life they will experience a 'day length' equal to the longest day they have known.

PRODUCTION IN DARK HOUSES

Moving from a light-rearing house to a dark laying house will stop the sexual development of the bird and delay lay for several weeks. This situation must be avoided if possible. Light duration in the production house must be greater than that of the rearing house at the moment of transfer.

LIGHTING PROGRAMMES

REARING IN DARK HOUSES

(Light intensity less then 0.5 lux)

In hot conditions you should have a minimum light duration of 12 hours to allow the birds to eat during the cooler hours.

Age and/or weight	Light duration		Production in light house		Production in light house
Age and/or weight	Temperate season	Hot season	Watts/m2	Lux	Watts/m2	Lux
1-2 days	22 h	22 h	3-4	30-40	3-4	30-40
3 - 4 days	20 h	20 h	3	20-30	3-4	30-40
5 - 6 days	18 h	18 h	3	20-30	3-4	30-40
7 - 14 days	16 h	17 h	2	15-20	3-4	30-40
15 - 21 days	15 h	16 h	1	10	3-4	30-40
22 - 28 days	14 h	15 h	1	10	3-4	30-40
29- 35 days	13h	14 h	1	10	3-4	30-40
36- 42 days	12h	13 h	1	10	3-4	30-40
43 - 49 days	11 h	12 h 30	1	10	3-4	30-40
49 - 119 days or over	10 h	12 h	1	10	3-4	30-40
1450g	11 h	13 h	2	15-20	3-4	30-40
1525g	11 h 30	13 h 30	2	15-20	3-4	30-40
1600 g	12 h	14 h	2	15-20	3-4	30-40
From 133 days	Increase 1/2 hour per week until 16 h 00		2	15-20	3-4	30-40

REARING IN LIGHT OR HALF DARK HOUSES

(intensity of perceptible light higher than 0.5 lux)

You can consider half dark houses as those where there are no windows but light comes in through cracks and is above 0.5 lux. In such houses we use the "light" house programmes.

The sexual maturity of the birds is influenced by the changes in natural day length light experienced in rearing. Note and take into account the natural light as at 17 weeks of age (119 days). The lighting programmes below are designed to give 50 % production at 21 weeks.

Rearing when natural light is decreasing

To avoid delay in sexual maturity you should start light stimulation by increasing by 2 hours followed by more gradual increases of 1/2 hour a week.

Rearing when natural light is increasing:

Between 49 and 119 days the light duration must be equal to that to be experienced by the birds at 119 days. To avoid too early a sexual maturity, stimulation should not be given until the birds have attained a body weight of 1450 g when 1 hour extra light can be given followed by 1/2 hour per week.

To avoid excessive precocity, stimulation will be given after 119 days at the rate of 1/2 hour per week.

Age and/or weight	Light duration at 17 weeks
Age and/or weight	<10 h	11 h	12h	13 h	14 h	>15 h
1- 2days	22 h	22 h	22 h	22 h	22 h	22 h
3 - 4 days	20 h	20 h	20 h	20 h	20 h	20 h
5- 6days	18 h	18 h	18 h	18 h	18 h	18 h
7 o 14 days	16 h	17 h	17 h	17 h	17 h	17 h
15 - 21 days	15 h	16 h	16 h	16 h	16 h	16 h
22 - 28 days	14 h	15 h	15 h	15 h	15 h	15 h
29 - 35 days	13 h	14 h	14 h	14 h	14 h 30	15 h
36 - 42 days	12 h	13 h	13 h	13 h 30	14 h	15 h
Decreasing days
43 - 49 days	11 h	12 h	12 h 30	12 h 30	13 h 30	14 h 30
50 - 119 days or +	10 h	11 h	12 h	12 h	13 h	14 h
1450 g	12 h	13 h	14 h	14 h	15 h	16 h
1525g	13 h	14 h	14 h 30	14 h 30	15 h 30	16 h 30
1600 g	+ 1/2 hour by week till 16 h 30
Increasing days:
43-49days	11	12	12 h 30	13 h	14 h	15
50 - 119 days or +	10	11	12 h	13 h	14 h	15
1450 g	11	12	13 h	14 h	15 h	15 h 30
1525g	+ 1/2 hour by week till 16 h 30