The role of environment and management on leg abnormalities in meat-type fowl.

Continuous light with 1 h of darkness at midnight is a common photoperiod for raising meat-type fowl. The logic behind the 1 h of darkness, usually provided between midnight and 0100 h, is to acclimate the birds to darkness in the event of a power failure. Increasing evidence from several research laboratories indicates that lighting regimens other than continuous light, such as intermittent or step-up lighting, can lower the incidence of leg abnormalities in meat-type fowl. Some evidence suggests that increased exercise contributes in part to the reduction in lameness due to lighting. Management can influence the incidence of leg and foot problems via effects on rate of gain, flooring systems, and litter moisture. Rapid weight gains have been correlated with tibial dyschondroplasia (TD), although more evidence is needed to determine whether other types of leg deformities, such as long bone distortion, are related to rapid growth rates. Using low intensity X-ray imaging (hand-held lixiscope), live breeders with TD lesions can be identified and the incidence of TD can be reduced in breeder flocks through genetic selection. In addition, turkeys can be selected for wider shanks to improve walking ability. Slippery surfaces should be avoided to prevent spraddled legs. With the exception of TD, broilers reared in cages have more leg deformities than floor-reared birds. Dry litter conditions can help prevent foot pad dermatitis caused by Staphylococcus aureus and other bacteria.