Here is a very interesting and educational video on ox hoof care and trimming from the Swiss Veterinary School in Zurich. I includes some nice slow motion views of hoof interaction with the ground surface.
Great video, finally had a good connection to watch it. Coming from the horse world cattle feet had some mystery to them. I have just been going with my gut feeling a few strokes with the rasp at a time, so far they seem good. This video certainly confirmed some of my assumptions such as the longer outer claw. A grinder and fancy shoot are nice, but I will take my rasp and steer that lifts his foot for me any day 🙂