RICHMOND, Va. (AP) -- Cattle producers who bring breeding-age cattle into Virginia will soon have to prove that their animals aren't infected with bovine tuberculosis.

A new regulation requires negative TB test results and proper identification for imported cattle older than 18 months. Imported cattle that don't have negative test results or proper identification will be quarantined.

The regulation goes into effect Aug. 15.

State Veterinarian Dr. Richard Wilkes says individual animal TB tests within 60 days prior to entering Virginia are acceptable. An annual whole herd test originating from TB accredited herds also is acceptable.

Wilkes says in a news release that Virginia is a bovine TB-free state. Identifying potentially infected animals from other states is critical to keeping the disease out of Virginia's livestock.

Copyright 2012 The AP.