Many of our neighbors mix ythe peas with hay barley for spring planting, cut it once and graze the re-growth. Seems to work good this way but I don't know of anybody that plants it strictly for grazing.
I don't think they'll hold up very well under grazing. The cattle will eat them into the ground and hoof traffic will probably destroy what's left, unless you want to move them onto and off of the patch in a VERY short period of time (few hours to a day maybe)??
Better like the other guy said... take em for hay and then whatever regrows let the cows eat when they start winding down and it doesn't matter if they don't come back when the cows are gone. JM2cnts. OL JR