I have also heard this is meant to be good for hormonal mares, do please let me know if you try it. I read loads and loads about different supplements and eventually I put my mare on Easy Mare Gold, by Hilton Herbs. It seems to have worked, and is still working. It does contain Valerian but it is a very low dosage so I can't imagine it does much. The Agnus Castus is the key ingredient. I'm actually impressed so far. Will have to see how it holds out!