You asked about my other roosters, only 2 of them are his age. The others are 3,5 7 & 8 years old. I only keep roosters that are non aggressive and get along with the other roosters so the young rooster in question is not harassed by the other roosters.
If a rooster causes problems he becomes supper.
I have around 40 hens with maybe 25 of them being breeding age. My hobby for the last 10 years is hatching chicks and guinea keets. I live in a small town of around 4000 people and the nearest town is close to 40 miles away. The only way to get chicks is to order them from hatcheries or buy them at the feed stores in March. A lot of people don't want to fool with raising babies so I sell newborns and a lot of fully feathered chickens and guineas. That's why I end up with so many chickens. (actually it's a good example of chicken math!)
All of my 57 birds free range thru the day and there are a lot of feeders in different places so there is access to food and water at all times. I have the vitamins in all the main water jugs.