Lighting programmes for broilers
Continuous light seems like it should maximise growth. It does not — it produces leg problems, sudden death and a worse FCR than a programme with a real dark period.
Awaiting veterinary review. This guide is written from published industry practice and has not yet been checked by our domain advisor. Confirm anything clinical with your own veterinarian before acting on it.
Light is the cheapest management lever on a broiler farm, and the most commonly misused. The instinct is simple: more light, more eating, more growth. It is wrong, and it has been known to be wrong for a long time.
What a dark period does
Continuous or near-continuous light produces:
- Leg and skeletal problems. The bird grows faster than its frame.
- Sudden death syndrome, particularly in fast-growing males
- Ascites in cold conditions
- Worse feed conversion, not better
- No rest, which matters more than it sounds
A dark period slows early growth slightly and lets the skeleton keep up. The bird then compensates later in the cycle. The usual finding is that final weight is similar or better, FCR is better, and mortality is lower.
The dark period must be genuinely dark. Four hours of dim light is not a dark period. Birds also need to learn darkness before it is imposed — an abrupt switch at week 3 panics a flock that has never seen it.
A workable shape
| Age | Light | Notes | | --- | --- | --- | | Day 0–3 | Near-continuous, bright | Chicks must find feed and water | | Day 4–7 | Introduce dark gradually | Build up to the programme | | Week 2 to ~3 days before sale | 4–6 hours dark, in one block | The working programme | | Last ~3 days | Increase light again | Maximise intake before sale |
Bright early light is not optional — a chick that does not find water in the first hours is a chick that never catches up.
Brooding: the first seven days →
Intensity
Bright for the first days — the figure usually given is around 20 lux or more — then reduced for the growing period, often to 5–10 lux.
Lower intensity in the growing phase calms the flock, reduces pecking and scratching injuries, and reduces activity-related energy use. Too dim and birds stop finding feed.
Practical check: you should be able to read a feed bag label comfortably at bird level during the bright phase, and see the birds clearly but not read fine print during the dim phase.
Uniformity is the part farms get wrong
A shed with bright patches under each bulb and dark gaps between them does not have a lighting programme — it has hot spots. Birds crowd into the lit areas, stocking density becomes uneven in practice, and the dark ends of the shed grow slower.
Space the lights so intensity is even along the shed, and clean them. Dust on a bulb in a poultry shed cuts output substantially and nobody ever notices.
LED, and the electricity argument
LED replaced incandescent on most serious farms for the obvious reason: far less power for the same light, and far less waste heat — which matters in a Pakistani summer, where every watt of lighting heat is a watt the ventilation has to remove.
With Pakistani electricity costs and load-shedding, lighting is also one of the few loads that is easy to run off a small backup. A shed that goes fully dark unexpectedly for hours will pile and smother.
Layers are a different problem entirely
Everything above is broilers. In layers, light controls sexual maturity: you never decrease day length during rearing and you increase it to bring the flock into lay. Getting that backwards costs you the production curve.