When you want your young pigeons to participate in national races, you can use pigeon darkening systems as a training technique. This technique accelerates the process of maturity and at the same time prevents their feathers from moulting. The darkening system will give young pigeons the impression that it is still wintertime and therefore they will keep their primary flight feathers.
In this video, Jos Thoné explains why and how he uses his pigeon darkening system. In this way, he keeps the feathers of his young birds in really good condition.