heat is definitely affecting us our heat index is hitting up near 120 every day, and even with a fan and frozen 2 liter bottles were down to two maybe three eggs a day compared to the 4-6 we were getting a week and a half ago. as for diet, the highest protein you can find, with some yogurt for a boost, if you notice youve got some that are serious about popping out eggs, you will want to supplement with oyster shell to keep their calcium up. also the more greens(free range/grass clippings and fresh vegetable leftovers) and bugs they get, the deep yellow to orange color youll get in your yolks.
Doesn't it seem odd that a tropical bird, the chicken, should have serious problems with heat?
Here is a chart from the University of Iowa showing when you should start paying attention to keeping them safe: Temperature and Humidity Stress. Really, it is whenever the thermometer goes above about 85°.
This University of Minnesota Extension Service information gives you some idea of how to deal with Heat Stress. Obviously, shade and ventilation are important. Electrolytes and vitamins are also suggested.
As the heat goes up, the food consumption goes down. As was said, feeding a high percentage protein ration is important since most of the protein in the diet is used for egg production. If the hen cuts down too much on her food, she may very well be taking in too little protein to produce eggs.
Hot days are not the time to allow them to load up on high-calorie, low-protein treats.