I've been raising chickens for about 7 years. Prior to my recent brood which just turned 3 in July, I used to slaughter them off every fall. As you can see from my ID, I live in the Desert SW and temperatures reach into the three digits in the summer, and I lost many of my initial hens due to the heat. Those were mostly dual purpose hens and they did not work out here in the desert. That's why I chose Leghorns. Concerning, my most recent brood, purchased 3 years ago, I lost one Buff Minorca (due to the heat), 2 Anconas (due to the heat) and 3 Single Breasted Leghorns (2-hen related*, one due to the heat). I did not find that eggs got significantly larger after having my hens over the years, despite reports that they are supposed to be larger. * Hen pecking, didn't get along with the Minorca or Anconas hens and was killed by them.