Saw this on the front page, thought I would respond even though I usually just lurk in the earth forum.
What I remember from veterinary school is that this is somewhat challenging to accomplish properly. You will need a lot of info on the genetic basis of the stock you have, and you will need to track that stock very carefully. A quick look over my old books shows nothing specifically about closed herd mgmt, it is such a niche that I suspect there might not be full book resources. I wonder if you might contact the county extension or the vet school at NCSU to see if they have seminars, their large animal program is very good.