I agree, you are giving them too much scratch. The layer crumbles themselves are formulated to give them everything they need to be healthy. The corn is a treat that they don't need and unlike veggies meat etc, which gives them a vitamin or protein boost, the scratch doesn't really benefit their diet, so it is purely a treat. You not only dilute their protein intake by giving them so much scratch but also their calcium unless you also offer oyster shell in a separate container. Their current diet could lead to them becoming fat/obese with it's associated health issues and also possible laying issues due to lack of calcium.
I would cut it back to no more than half a cup of scratch a day. I give my layer flock of 14 hens/pullets about a cup of soaked/fermented scratch which has usually swelled to nearly twice it's dry volume, so effectively half a cup of dry grains between 14 of them once a day and I worry that even that is a bit too much. I butchered hens for my neighbour that had been given a roughly 50% mixed corn : layer pellets ratio diet and I was shocked to find their organs encased in solid yellow fat deposits. They were all poor layers which is why he wanted rid of them. I have been much more strict with the treats dished out to my girls since then, but they have free access to layer pellets throughout the day.
Best wishes
Barbara
PS. You may find that there is less waste by using pelleted feed rather than crumbles and/or fermenting some of their crumbles/pellets and giving them that as a treat instead of the scratch. It's surprising how they get all excited by a pan of fermented feed when they pretty much ignore their regular feed. It's a very simple process and provides beneficial enzymes for their gut, so improving digestion.
