I think that has to do with the manner in which the layers are cared for. Chickens and cows don't produce eggs or milk at the same rate throughout their lives.

I think that has to do with the manner in which the layers are cared for. Chickens and cows don't produce eggs or milk at the same rate throughout their lives. So farmers cull them once their production drops below the economical point. Also the majority of the males are culled since they're not producers. My grandfather thought it might be worth while to breed dairy cows with a meat producing aspect due to the 25% yearly cull rate.