When there are multiple chickens in one cage, and you take the one chicken that lays the most eggs and choose those eggs to start thye next generation with, in 6 generations you get a hyperaggressive chicken that attacks any other chickens in the cage, and egg production plummets.
But when you choose the eggs of ALL the chickens in the cage of the chicken that lays the most eggs, in 6 generations you get peaceful, docile chickens and 160% greater egg production.
So anyways. Chicken tastes good. Egg tastes good. And don't bring a pigeon to a cock fight.