Brucella ovis is a bacteria that affects the epididymis of rams leading to significant infertility issues.  It is currently a problem mostly in southern and western United States and those states in between, thus the import requirement of a negative test in those states.  Testing is not performed at many labs.  Historically, Colorado State University (at their WESTERN SLOPE lab) was the lab to do this test, Texas A&M and Washington State also do that test.  The blood must be pulled and submitted by a veterinarian to be valid on a health paper.  

It is probably easy for people, especially cattle producers/cattle vets, to hear Brucellosis testing and think of common cattle testing for Brucella abortus.  This type of Brucella causes abortions and can cause illness in humans.  Because of it's history as prominent cattle testing, most labs do this test.