I have 2 roosters simular age.on bout 8 months and one that hatched 1 week before the other one. Well the older one has matured now and is crowing and has all the rooster features. But for some reason the other bit younger one is still growing bigger taller and doesn't have any big red comb yet.has medium wattles. Hasn't started crowing yet.they are in the same pen with 9 hens. I'm thinking because there's one dominant rooster the other one isn't becoming a rooster yet with all its features. Because I killed an even older dominant rooster couple months ago.then it didn't take long for the dominant rooster I have now to start crowing and become boss.so that's my theory. If anyone knows other info on this. There father is a Australorp x. Not sure what with.and there mother is a is a brown hen. There colours are white with brown patched wings with some flecks of black amongst there feathers.