No ideas on getting deer over cows on cam with them both being there for the same reasons. You might concentrate the cams on the edge of the thicker brush down in the draws. We have that issue on one of our places and I usually will drive around after a rain and pick up main trails that have mostly deer tracks on them and put the cams after other trails have met up with the main one. It's really a crap shoot until you start getting pics and figure out how to adjust the cams from there.