Ear notching is the only approved method for marking pigs for registration. It is arguably painless, quick, easy, robust and reliable. Please take a look at the following document for detailed information.
Ear tags are not approved for registered Large Black Hogs. The LBHA experimented with them for a few months but it became very clear that, given the the large ears on the LBHs, tags would not work. Notching with a proper ear notching tool is humane, safe and reliable – more so than ear tags that can rip out.
If you wish to use tags, you are free to do so. However, tags alone will not work for registration – your pigs must be notched as well.
Notching for pedigree, registered animals is approved by the USDA and most states allow transfer of pigs with notching because of this. If you are transporting pigs into or around your state, please check with them about the requirements they have. You may have to remind them that the USDA approves notching for registered animals!