Honestly I have had chickens for about 15 years now, and I live in the southwest desert, and normally always buy from Tractor Supply or Walmart when in a bind and sometimes from the really expensive feed stores out in the country where I live when I really needed food but couldn't get to town.

My experience is that the food isn't the problem. I have mostly all of the same age chickens now because I ordered a bunch online that are about a year old now (about 40 and split it with a friend of mine), and I have 4 older hens that might lay but they are old and will die soon. We have separate rooms in a large (40x40 foot pen), and can separate when needed for breeding or to find out who is laying and who isn't. Its a pretty good setup and I am working on building a fence around my property so I can let them free range in the yard during the day, but right now they are in that pen and all of the doors are open because there is only one rooster which means they aren't fighting and such. I also added lights to come on a bit before sunrise and stay on after sunset so that the chickens stay awake longer and think its daylight longer.

When we got down to one rooster, at the same time was when we added the lights, this was in November. That is when we went from getting maybe 5 eggs a day to 15 eggs a day! I think the minimal stress of extra roosters competing along with the lights, and if the hens are pecking each other get rid of the ones doing the pecking so that there is minimal stress, and you will always get a successful yield. Of course unless they are poisoning the food! But I think the food thing is either a conspiracy theory or a regional issue with a certain plant that does the packaging of the food.

Good LuckQ!

p.s. the Q was a typo but I left it because it is serendipitous!