Day one if you are VERY EXPERIENCED. Most hatcheries have people on staff (usually Japanese based on the need for sexing in a country with limited space) that sex day old chicks. They squeeze the chick to release fecal material then flip it over, open the vent and look for a small lump to determine male or female.
Roosters tend to have larger combs, wattles and fancy tails. They crow, hens chirp. Hens tend to be smaller and duller, roosters are bright and cheerful. Hens lay eggs, roosters don't.
A term rooster is used for the male bird (the hen is a female bird) of certain species . There are chicken roosters and hens, pheasant roosters and hens, turkey roosters and hens etc. Ducks are drakes and hens. Geese are the "Goose and the Gander".
Well, hens are girls and roosters are boys...that cover it?
For adult chickens, roosters are generally a bit bigger, and have longer, showier tail feathers. You can also tell by behavior. Roosters will tend to be more commanding, and will usually avoid other roosters if they have enough space and there are enough hens, or else fight with them if the space is too small or there are not enough hens. They can also often be observed jumping on hens' backs to mate.
It is likely that the roosters are aggressive, too rough with the hens, or that there are not hens in ratio to the amount of roosters.
Hens
The amount of roosters needed for breeding hens is about one rooster per ten hens
Hens.
No.
Yes they will.
Better to say 4 roosters is too many for 4 roosters. The 6 hens can wait a bit and soon there will be one rooster a-go-go, one in the hereafter, one running away, and one squating on the ground. The hens could deal with 6 roosters, but the big boy a go-go won't stand for more than him with his flock. actually 1 rooster needs 5 hens to be satisfied other wise roosters will fight One rooster will service (fertilize the eggs of) up to 6 hens. If you have more than 6 hens, you will need another rooster. 4 roosters on 6 hens is not good. The roosters will fight and the hens will be exhausted running from all the roosters.
roosters fertilize the eggs but they dont raise the chick