Heat detection patches are applied to the tailhead by means of a sticky adhesive. The patches are white in color with a red dye pouch on one end. When cows are mounted by another individual, the pressure of the mount ruptures the dye pouch and the entire patch turns red. Any breed of bull can be used for this job. However, large, heavy bulls should not be used because they can injure young heifers or small cows when they mount them.
Many producers use Jersey bulls because of their small size.
Be aware though, that any breed of bull, particularly dairy bulls, can become aggressive and need to be handled with caution. Gomer bulls do make good heat detection aids because they are naturally adept at identifying cows in heat. Androgenized cows are females that been given the male hormone, testosterone, to stimulate them to show male behavior. Androgenized cows are often safer to work around than gomer bulls. Producers may choose a cow that can no longer produce calves, is a poor producer, or is a freemartin heifer.