The "tumbleweed" that grows where I live is mostly Kochia. It is listed as a forage crop for sheep and cattle. Our horses used to eat it when they had a chance, and the equine vet told me they went for it because it had more protein than other choices. My daughter's Arabian developed sunburn dermatitis on his muzzle, the vet said that tended to happen in horses that were eating a lot of Kochia. Between the protein and the sun sensitivity problem, I'm not feeding Kochia to my torts.