Light intensity has been shown to affect the activity of birds, but most studies have focused on constant light intensities to determine their effect on welfare. Light intensity preference behavior of birds has been suggested to be an additional component of bird welfare.
Blackhead disease is an important disease in the commercial turkey and chicken industries. The disease is introduced to turkeys by transmission of the eggs of the cecal worm Heterakis gallinarum by contact with chickens or chicken litter.