I also mix oregano leaf into their crumbles, I buy in bulk. I also grow some herbs and berries in their outdoor run. Many things will survive if the roots are protected from being dug up. You can lay hardware cloth around the base of the plant, or build shallow frames covered in hardware cloth so they can only eat what is tall enough to stick out, saving the roots, a good way to provide tender greens. I feed lots of chickweed in the spring when it's coming up all over my garden (I don't use pesticides or herbicides, so all is safe). I also use aloe, they will eat it if you put the leaves or plant in the run, and I've used this http://www.lilyofthedesert.com/product/aloe-herbal-detox-formula/ which has sometimes helped with ascites, which often happens with salpingitis, temporary help, but has made them more comfortable without draining. You can also put down some large rocks, blocks or even a plank or plywood and leave for a few weeks undisturbed, then move it to a new spot. It will be full of all kinds of bugs & stuff underneath, free chicken treats and nutrition and entertainment. As previously stated, do some reading, there are lots of sites and books on the benefits of herbs and other plants. Many people use garlic, but be cautious. Garlic has health benefits, but is also toxic in large quantities, and we are talking about 4-6 pound birds in general. Sometimes it's just trial and error to see what helps.