Before breeding season begins, Glenn Selk, beef reproduction specialist at Oklahoma State University, offers some bull-management tips that can increase pregnancy percentage.

  • In multi-sire pastures, make certain that the bulls that will be pastured together have been in a common trap or pasture prior to the breeding season. “Bulls will establish a social hierarchy,” he says. “It is better to get this done before the breeding season begins rather than wait until they are first placed with the cows.
  • Keep young bulls with young bulls and mature bulls with mature bulls. “Mixing the ages will result in the mature bull dominating the younger bull completely, and in some instances causing a serious injury,” says Dr. Selk. If you plan to rotate bulls during the breeding season, then use the mature bulls first, and follow with the yearling bulls in the last third of the breeding season. “This way, the young bulls will have fewer cows to settle and will be 1–2 months older when they start breeding.”
  • Determine optimal cow-to-bull ratio for younger bulls. “For these young bulls, a conservative rule of thumb is to place them with roughly the same number of cows as is his age in months,” says Dr. Selk. For example:

     Bull age    Females in
   months   breeding pasture
    12–15   10–12
    15–18   12–18
    18–24   18–25
    > 24 25–35

“Some bulls are known to be successful breeding 50 or more, while some are failures with only 10 cows,” he adds. “Observing bulls early in the breeding season may give you a little idea of the libido and breeding capacity of the bull.”