Too much scratch can lower the protein percentage of your feed and cause deficiencies. In turn, chickens may peck at other chickens--especially young layers and production birds. Usually not when they're on five acres of space, though, so I doubt that's it. Besides the lump, are there any other symptoms you've noticed?They free range on 5 acres but stick close to their coop mostly. I only have 4 hens, and they eat layer food as well as what ever bugs and things they eat and some scratch mix as a treat.