Haha, maybe you have apple connoisseurs and they don't like the selection of type of apple, haha. Hard to say. Chickens are funny. There's some things my girls don't like that other people say their chickens go bonkers over. I suppose its like people. Some people don't care for some foods that others can't get enough of. Don't worry about it. There's even been some foods that my girls didn't care for when they were younger that now they like. I suppose its possible chickens' tastes change with age just like people do.
Its good that you are thinking about making sure you keep a balanced diet. High protein is needed for good egg production, so if you notice a drop off in the egg production (when they get to that point), then you'll know to up the protein. If they get too much fat in their diet it will also reduce production, and make them gain unhealthy weight. Because I live in a northern climate I will slightly increase foods (like corn) just to help them deal with the cold. They get no corn in the Summer. The largest portion of food they receive everyday should be the feed. Also, it can't hurt to remind you that fresh water should always be accessible.
Just in case you haven't stumbled across the info yet, seeing I'm talking about reduced egg production. Not all slow downs in egg laying are diet related.
*Chickens will produce the heaviest in their first 2 years of egg laying.
*Some breeds naturally are heavier producers.
*When chickens are molting there will be little or no egg production (because all the energy goes into new feathers, which btw, you should up the protein and calcium in their diet to help the process).
*Big stressors will also cause them to slow down or stop. For example, last Summer a tornado went through our neighborhood and a neighbor's chickens stopped laying for a month. My girls hadn't started laying yet, so my girls didn't have egg production yet to worry about.
*Hours of daylight plays a huge roll in egg production, so in Winter if you're not providing lighting for them, expect fewer or no eggs.
*Of course there's other health and disease issues that could affect egg production.