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.
Best Answer: It different among the breeds of cattle, but cows can breed well into their 20's. Some breeds like the Texas Longhorn cattle have been able to breed into their 30's. Depends upon how tough her life is out in the pasture. Well fed and kept free of parasites she can live to maybe 20.