the urine breaks down to amonia, probably before you even buy it. But I think what the attractive part of it is the scent of the glands not urine itself. Im not expert on this but that is my understanding and it makes sense to me (no pun intended) Ive been using synthetics for the past 2 seasons, they have an indefinate shelf life and I had some success with them last year. my 2 cents ( again no pun intended )