Do the cows not eat the pods? There actual been research using them in pasture setting to provide extra feed as pods and shade for the cattle. I've seen sheep eat the pods like candy and their seedlings. Turn them lose in new pasture and first thing they would go for was the honey locust seedlings. The pods have a high nutrition and should be good feed. Here is one link to some information on:
http://pubs.cif-ifc.org/doi/pdf/10.5558/tfc67232-3
The research I am more familar with is done at Virginia Tech at Kentland Farms, but could not find a good link to the information at the moment.
Maybe cows are not as ready to eat the pods and seedlings as sheep. But you could always co-graze if you want to work with the honey locust instead of againist it. Just some thoughts!!