Required tests for certification in the NPIP are Salmonella Pullorum/Typhoid. This needs to be done in order to become NPIP certified. Once certified I can sell my extra eggs, chickens over 5 months old and enter them into a show (think Deerfield) if I like. I also can't bring other birds or babies into my flock without them being from an NPIP flock or I invalidate my status.
I just had my chickens tested yesterday. Think it's a good idea. you never know what wild birds will carry & bring in. since I am starting to sell eggs , it's really important . about birds from an untested flock, thanks for that info. I didn't know that.