How many roosters to chickens and how many of the eggs get fertilized?
Varies by breed and individual chicken disposition. For both the rooster and the hens.
I maintain about a dozen to a eighteen hens of various types and age and a single, but very assertive rooster. Every egg is fertile, though most eggs are refrigerated the evening of, or the morning after they are laid.
Twice a year I allow a brooding chicken to sit on a clutch of eggs for chicks, though with the level of effort I put into keeping up the bug eating brood, most don’t make it to egg laying age. I replace the rooster every third year or so, by allowing natural selection by challenges from younger rivals.
Nature at the zenith...... the eggs are a great perk.
I keep one rooster per 12-15 hens. When the rooster gets to the aggressive age, we hatch out a few of the eggs and raise another rooster. The older goes to the freezer.
I usually only incubate 5-10 at a time and only a few are quitters so most are getting fertilized.
There’s nothing different about fertilized eggs, they look and taste the same. They do not incubate unless under a hen or in an incubator.