As I wrote back here, we keep lots of hens because we like to have eggs through winter (hens tend to stop laying as many eggs in winter, but if you have enough new layers, you will still get a few eggs each day). The cheapest way to have lots of hens is to hatch your own chicks. We have a 48 egg incubator, and we usually hatch around 30 chicks from a full incubator. Of those 30, half or so will be hens and the rest roosters.
We keep one rooster for every 8-10 hens, depending on whether these roosters get on or not, sometimes its possible to have two in the same yard. We currently have three rooster, two from this year's hatch and one from last year. Of the two from this year's hatch, one we chose because he's a big Rhode Island Red rooster, and the other one just moved in with a chicken tractor of hens, so he gets to stay too. Usually only one rooster will move in with a group of hens who have no rooster. If the hens accept him, then he can stay with them.
One of the biggest factors in egg hatching rate is the rooster. Not just his fertility, but whether the hens like him. As Harvey Ussery wrote in the best chicken book I've ever read, the rooster needs to woo his hens, by calling them over for choice bits of food and doing a little rooster dance before he mates with them. If the hens don't like a rooster they will just run away from him, and you won't get many fertile eggs.
So.... if we let the hens choose their rooster, we get more fertile eggs, and then we get more roosters for them to chose from.
We keep each rooster for 2-3 years. We find that the older roosters get challenged by the younger ones and eventually we have to remove them (sorry readers, they don't go to rooster retirement homes, we cull them when we do the old hens). Unfortunately old roosters, no matter how long you cook them, do not get more tender (believe me, I've stewed one for 24 hours). They are best as dog food or buried deep in the compost.
And what happens to the other 10-12 roosters that don't get selected by hens (or by us) to stay? The young ones are very tasty. We raise them to be meat chickens, and you can roast them (don't forget to make stock from the carcass). For the older hens we prefer to mince them.
How do you choose a rooster? Do you hatch your own? And what do you do with the extras?
Find out more about chicken tractors in my eBook Design and Use a Chicken Tractor