Although female broiler breeders can be molted quite well and can start a new production cycle after molting, male broiler breeders react very bad on molting. Any reduction on body weight results in an immediate drop in fertility, increase of the number of cull males and increase of mortality. If the body weight is increased again after the reduction, a high number of males do not come sufficiently back in production but remain of poor quality, not able to mate.
If a flock of broiler breeders is molted, the males should not be molted but replaced, and they should be sexually developed by the time the females are coming in production again.
It is not exactly clear why males react so bad on body weight decrease in contrast to the females, that can handle it much better.
One of the reasons might be the difference in body composition. While females can grow substantially fat after peak production, males grow relatively much more in protein. This means that if body weight decreases, females will first of all loose fat. On top of that, the females can also decrease the size of their liver and the size of their reproductive tract and especially the active follicles, before they have to give in body muscles.
Males do not carry a lot of fat, even at high bodyweight levels. This means that a reduction in body weight will very quickly cause a reduction in muscles, and that is very tough for any animal.
If males must be kept inactive for a while, probably the best way of handling is by keeping them on low light intensity and duration and at a constant body weight by giving them only feed for maintenance.