There are many many herds that utilize the sale barn to sell their cattle, and unless you have personal relationships with individual buyers and sellers, it is " Buyer Beware" in terms of health status on an each animal, unless the herds you are buying from are Johnes, Bang and TB certified free herds and that is published or spoken prior to the sale of the animal
Sale Barns also hold Breed/Seedstock sales, dispersal sales ect.
Because Johnes is not a federaly monitored disease it is not manditory to health test for this disease, We test annually, and at the request of buyers, it is a good service to provide, and will lend crediblity to your herd health program, and the quality and consistency of the cattle you provide
This disease is not as critical as BSE, the only tests available for this are brain tissue tests, thus depopulation and tissue tests are all we have to go by, Johnes on the other hand, we have two test ELISA and fecal, for cattle that test positive on the ELISA, test again with fecal to varify positive animals and sort into different managment groups or cull.
Sale barn are great, I use them myself for culls, and so do lots of other ranchers, and small herd owners, 50 and under herds.
Greater premiums are acheived through retained ownership and private marketing of your stocker calves, a little homework can pay great dividends, when cattle are marketed outside the sale barn.