Dr. Glenn Selk Offers Advice On Properly Managing Your Multi-Sire Pastures This Breeding Season

By Dr. Glenn Selk

Dr. Glenn Selk, Oklahoma State University Emeritus Extension Animal Scientist, offers herd health advice as part of the weekly series known as the "Cow Calf Corner" published electronically by Dr. Peel and Dr. Glenn Selk. Today, Dr. Selk discusses the ins and outs of using young bulls in multi-sire pastures and pin-pointing a good cow-to-bull ratio.

"The spring breeding season is only a few weeks away. Cow calf operators are assessing their bull batteries and making needed purchases. Producers often ask about the use of young bulls in the same breeding pasture with older, larger bulls. In most instances, this is a practice that should be discouraged if at all possible. Young bulls will normally lose the battle of deciding who is the dominant individual in the breeding pasture. Ranchers report that in some cases young bulls that have been severely “whipped” are less aggressive breeders after that incident. Australian data on multi-sire pastures have shown that some young bulls gain a dominant role as they mature and breed a large percentage of the cows. Other bulls will not gain that dominant status, and only breed a very small percentage of the cows in a multi-sire pasture for the remainder of his stay at the ranch. The best solution is to always place young bulls with young bulls and mature bulls with mature bulls in the breeding pasture.

"In some situations, the rancher may choose to use the mature bulls in the first two-thirds of the breeding season, and then rotate in the young bulls. This allows the young bulls to gain one to two months of additional age and sexual maturity. In addition the young bulls should have considerably fewer cows in heat at the end of the breeding season as the mature bulls will have bred the bulk of the cows or heifers. The young bulls will be in the breeding season only a few weeks and should not be as “run down” or in poor body condition at the conclusion of the breeding season.