You need to use a decoy with your cow calling. A bull will come in LOOKING for the cow but if he doesn't see any sign of her he will hang up. A Montana cow elk decoy is the ticket.
My friend shot a deer, gutted it and brought it back to camp in the back of his truck. He saved the heart and cooked it for dinner. Unknowingly the spare gas can in the back of his truck leaked out gas. One bite of filla-mon-heart and we were all gagging. Hard to believe it didn't blow up when...