As birds depend for the stimulation of their reproductive system on an increasing day length, the day length (hours of light) during both rearing and production should be well controlled.

However, birds do not need a full hour of light to contribute that hour of light to the total day length. If a part of that hour is dark, the birds still considers that hour to be light. In other words, if 8 hours of continous light is replaced by 8 hours of 3/4 light and 1/4 dark, the bird still considers this to be an 8 hour light period.

This system is called Bio-mittent light system or BMLP (Bio Mittent Lighting Program), and is used in commercial table egg production (caged layers) to save on feed (less activity) and energy (less hours of light). Although in layers it is mainly used in rearing and sometimes post peak, research has shown that it can be used throughout the rearing and production periods.

Although this system is used in caged layers, it has not, or very limited, been tested in broiler breeders. Although some advantages similar to those in commercial layers can be expected, some possible disadvantages have to be taken into account.

- Application during rearing will decrease the activity of the birds, which will have a positive effect on their stress and nervousness. It will however probably also slow down their motion and mobility, which can negatively influence their bone and muscle strength.
- Application during production might result in more floor eggs, less uniformity and less fertility as the activity during the dark periods will be decreased.

However, not much research on bio-mittent light programs for breeders have been done, and actual results can vary from this expectation.