On the NPR program "The Splendid Table" the host was answering a trivia question about egg sizes and stated that a hen has in her body at birth all the shell making material she will ever have, and that as a bird ages her eggs will gradually become larger. That is why young birds lay small and medium eggs and more mature birds give jumbos, but the jumbo shell is thinner and easier to crack. Does this make any sense to folks who really know chickens? I know any female vertebrate-avian or mammalian-has all the OVA she will ever produce in her ovaries at birth (before birth really) but shell making material is constatnly being taken in-thats why we have to make sure the diet is correct and suppliment with oyster shells,etc. Any thoughts?