CHEYENNE, Wyo. (AP) — The Wyoming Livestock Board has issued an order aimed at preventing the spread of a venereal disease in cattle called Trichomoniasis (trik-oh-moh-NIE'-ah-sis), which can cause cows to lose their calves.

The order covers all or parts of Lincoln, Uinta and Sweetwater counties in southwest Wyoming. It requires all bulls nine months and older that come from or into the area to be tested for the disease before May 31 and before they are placed with female cattle.

Bulls are the main carriers of the disease.

The order was adopted this week and supersedes an order adopted in March that covered only part of Sweetwater County.

State officials say seed-stock producers may apply with the state veterinarian for a test exemption for virgin bulls.