If depressed breeding in rooster like with humans exhibiting low "T" (testosterone), then consider a bumping up activity of his largest muscle group. His breast muscles. If he will let you handle him, then repeatedly toss him on a table so he has to flap at least a little to soften landing. The workout will potentially bump up testosterone produced by muscle mass to supplment that produced by testes. You may find he comes to like increased activity. Similar breast muscle workout could be induced by enticing him to fly a couple feet up repeatedly for a something like a meal worm. My games tend to get cockier after such workouts.