If your pigeons are extremely healthy, going into the breeding season, and you as the owner provide every possible grain, pellet, vitamin and mineral, there is no reason why the breeding pairs cannot raise six to nine rounds without any detrimental effects. At McLaughlin Lofts, we allow our very best pairs to raise their own young, starting in February and, in some cases, finishing in October or even November.
If you become lazy and do not keep the mineral supplements readily available, along with all the grain and pellet mixes, you could have health issues. The breeders will wear down, due to mineral deficiencies. Keep the minerals fresh and plentiful, and you will not have a problem. Vitamin deficiencies will not affect the pigeons, as would mineral deficiencies.
It would drive me crazy to have my best, old, hens laying eggs in the flight pens, when they could be raising youngsters in the breeding pens. If you separate and your hens keep laying, Mother Nature is telling you they were not ready to stop.