tealboy ; all these ideas are good,the only problem is anything that deer eat the cows will eat also.
can you put a couple strands of barbwire around a small spot??it only takes 30' square.
I have one place that has cattle on it (did have two,but they moved the cows out).I use corn only,the cows will get a little,but it being scattered over a large area the cows don' t bother me much.of all the pic' s I have there are cows in only two of them.
As for the deer taking a long time to find it ; and not knowning what it is,it only takes one time for them to see it and then they eat it.
Try the wire feed station,two strands will stop the cows,put something that smells to get the deer to come from down wind.
Good luck.[:-]