USDA Livestock Traceability System
The USDA has announced a new livestock identification program to help officials track animals' movements in the case of a disease outbreak. The new program is mandatory, but limited in scope to animals being shipped across state lines and gives states the authority to determine how animals are identified.
As of March 11, 2013, dairy cows and sexually intact beef cattle over 18 months of age must be registered when they are shipped over state lines.
More information on USDA animal traceability program is available at http://www.aphis.usda.gov/traceability.