The Animal Health Board is warning dairy farmers throughout New Zealand, to make sure any bulls coming onto their property are disease free.
Regional co-ordinator Frank Pavitt of Hamilton says the risk of what are called service bulls introducing bovine tuberculosis into a herd has increased, as more land is converted to dairying.
He says service bulls on many dairy farms are the only animals brought onto the property.
Mr Pavitt says ultimately the onus for ensuring bulls are disease free and have been TB tested, lies with the suppliers of bulls, not the dairy farmers who lease or buy them.