Most form pairs during the breeding season, but in some species, such as fur seals, the gray seal (Halichoerus grypus), and elephant seals, males (bulls) take possession of harems of cows and drive rival bulls away from their territory.
Look for the crooked tail. This is probably the best ways to tell if a cow has been bred: A cow or heifer will have a crooked tail or a tail that is held out in an odd angle than usual for 24 to 48 hours after being serviced by the bull. 1  4 Edit step.
Breed your cattle. Know when your cows go into estrus, when they're ready to breed, and go from there. If you are using a herd bull, you will not need to worry about when your cows go into heat, only when they have been bred for record keeping.