Sure, go ahead and try anything that won't hurt the bird, but don't get your hopes up, 'cause hypericum has not helped any of the birds I tried it on.Whether theres no "cure" for Marek's disease, or not, I can speak from personal experience, as can many others, that Hypericum is a miraculous cure for many chickens as far as whatever it is that ails them. People are WAY behind the times in figuring out the diseases of birds, and the cures, because frankly? No one used to care. So MY personal take on it is this. Do whatever you think you need to do. If Hypericum helps you (which it very well might) go for it. If it doesn't, at least you tried.
-Kathy