The semen described above was collected from donor stallions, which ... have undergone the following animal health tests ... a test for conatgious equine metritis carried out on two occasions with an interval of seven days by isolation of Taylorella equigenitalis from pre-ejaculatory fluid or a semen sample and from genital swabs taken at least from the penile sheath, urethra and from the urethral fossa with negative result in each case.