One! Or your hens will likely be over mated by two cockerels even if they get along.
I personally keep at least two of each breed and variety... if I can, in case something happens to my top choice or if I'm working on increasing genetics. Accidents, predators, and illness are all possibilities and I worked too hard to forgo my selected rooster... especially if I don't have any current grow outs or eggs in the bator.... My goals are very specific and I keep ALL my boys in stag pen. Some get to stay longer than others. And some get visit the hen flock every other day (so they maintain their pecking order to return back to the stag pen and swap pen swaps are done in darkness) or possible breeding pens depending on my intended goal at the time.
That being said... I fully intend on employing tethers... for some of boys who won't play nice if needed, and so the hens can visit by choice.
It is an ongoing learning adventure!
