Many people still believe that 24-hour lighting can maximize broiler chicken performance. However, continuous or near-continuous lighting programs (with only one hour of darkness) during the rearing period actually fail to maximize growth or Feed Conversion Ratio (FCR) performance. In fact, it can negatively impact the health and welfare of broiler chickens.

A proper lighting program can optimize economic outcomes while enhancing broiler welfare. Regular periods of light and darkness create a natural routine for the chickens, allowing them to experience natural growth, development, and behavioral patterns, including sleep.

The main components of a lighting program include light duration, dark duration, light color (wavelength), and light intensity.

Simpler lighting programs are generally easier to implement and provide more consistent results. The “best” program for each flock is influenced by the following factors:

• Age at implementation: Applying the program early on tends to provide the greatest benefits to chicken health.

• Harvest age: Chickens harvested at an older age tend to benefit more from longer dark periods.

• Growth rate: The impact of a lighting program will be greater on fast-growing chickens.

• Equipment availability and management: Longer dark periods can make chickens more aggressive when eating and drinking once the lights are turned back on, leading to crowding at the feeders and drinkers.

Table 2. Example of a Lighting Program for Broilers with a Target Weight of ±2 kg

All local regulations regarding dark periods and light intensity must be followed and given priority over the advice provided here. The dark period must have a light intensity of less than 0.4 lux. To test this, stand inside the house when the lights are turned off. If any light leakage is still visible, it must be fixed immediately.

Changes to the lighting program should be made gradually over 2–3 days to allow the chickens to adapt. Sudden changes in light duration can cause a sudden drop in feed and water consumption, thereby hindering the chickens’ growth and health. Using a “dusk/dawn” program, where lights are turned on gradually, helps chickens wake up and start eating progressively so as not to overwhelm the feeding and drinking systems. Staggering the dark period times between different houses can also help prevent the farm’s drinking water system from becoming overwhelmed when the lights come back on.

The use of an intermittent lighting program, where the dark period is divided into two or more parts, can increase growth rates. Such programs should be kept simple for easy implementation. It is recommended to have a minimum dark period of 4 hours in every 24 hours, and all local regulations must still be observed.

Chickens have a different visual spectrum compared to humans and possess light receptors in both their eyes and brains. Chickens see better in the ultraviolet spectrum, making the gallilux unit more appropriate than lux for measuring light intensity in chickens. Most agricultural light meters have a conversion guide between these units, or a specialized gallilux meter can be used. Note that standard lux meters are less accurate for measuring LED lights due to the high blue light content in LEDs. Therefore, an LED-specific lux meter should be used for more accurate results.

Light intensity must be uniformly distributed throughout the house to avoid chickens crowding in specific areas. The difference in intensity between the brightest and darkest parts of the house should not exceed 30%. Ensure that light placement is even, all bulbs have the same specifications, and broken lights are replaced immediately.

The warmth or color temperature of a lamp is measured in Kelvin (K). Smaller chickens tend to perform better under cool light colors, whereas larger chickens require warmer colors. For flocks with a target weight under 2 kg, a light of 5,000–6,000 K is recommended, while for chickens over 2 kg, 3,500–4,500 K is advised.

There is not yet clear evidence regarding the effect of light color on broiler performance. However, with the increasing use of LED lights, color adjustment has become easier. Blue or green wavelengths (450–560 nm) tend to calm chickens, improve FCR, leg health, and survival rates, while reducing the number of cull chickens. Meanwhile, the red spectrum (>620 nm) appears to stimulate broiler growth.

The type of lamp used does not seem to significantly affect chicken performance as long as it produces white light. Therefore, lamp selection is mostly determined by cost and availability. Chickens have a high ability to detect light flicker, which can cause stress and reduce normal chicken behavior. Fluorescent or LED lights with a high frequency (>200 Hz) should be used to avoid flicker detectable by chickens. Domestic LED bulbs are generally not durable enough for poultry house conditions and should be avoided.

In hot weather, if environmental controls are limited, the dark period should be set at night to improve chicken comfort. Research from Aviagen shows that each broiler chicken only spends about 90 minutes per day eating and drinking. Even with a relatively short light period, as long as adequate feeding and drinking equipment is available, all chickens will still have enough time to eat and drink.

Implementing a lighting program is a simple and inexpensive way to improve the health, welfare, and performance of broiler chickens. Further information regarding broiler lighting can be obtained through the Aviagen Info Center.