You don't set your dragons on breeding or not breeding, it's all about the food you give them. If you don't want them to breed, you have to feed them arid crystals, if you want them to breed you need to feed them feracious crystals. If you feed them petfood (arid crystals) and want them to breed again, it takes several days for them to gain ardor and zeal again, not sure about the time though.