My hens have been laying a few weeks, nice large eggs, hard shells. However, the yolks are dark enough but nothing like the dark orange yolks I got from a flock 3 yrs ago. My hens free range, get kale, spinach, corn once in awhile., sunflower seeds, scrambled eggs, layer ration and meat 2 x a week. The only difference is that my last flock ate a lot of dried seaweed, these guys won;t touch it. Can someone tell mw what I might add to their diet to darken the yolks?