Managing Yearling Bulls

by Gordon Jones, Ph.D.

In a progressive purebred herd, the young yearling bulls usually represent the most advanced genetics available to the commercial industry. If appropriately managed, these yearling bulls can be used at the age of 14-15 months with excellent results. The Red Hill herd has been developed from herds that have been successfully using yearling bulls for many generations. Yearling bulls are also used extensively in the Red Hill farms breeding program. We have had no difficulty with yearling bulls maintaining appropriate body condition during the first breeding season; however, we use the bulls for only a 60-day breeding season.

The yearlings in our sales have been developed to optimize growth rate, skeletal development, and sexual maturity. It has been our goal to give the bulls an opportunity to express their growth potential along with genetic differences for intramuscular fat and ribeye area. Even though the bulls are not as fat as if they had been developed on a higher energy ration, they are still in excellent body condition with some extra fat that is likely to be lost during the first breeding season. Yearling bulls may be mated to cows or heifers during the first breeding season, but we prefer to use them on only 15-25 females during the first breeding season.

At 14-17 months of age, bulls certainly are not mature in size, and, consequently, a portion of the nutrients consumed should be going toward growth in addition to being used for body maintenance and breeding activity. In our area of the county where fescue is the predominant spring pastured forage, it is difficult to get enough nutrients into young bulls because of the high water content of the forages. Therefore, most young bulls are likely to lose most of the added body fat that was deposited during the growth period up to a year of age. For this reason, we recommend removing young bulls from the females after the breeding season to allow the bulls the opportunity to gain some of the condition they have lost and to continue growing at an optimal rate.

Yearling bulls may be used in multiple sire groups with other yearlings; however, we discourage the use of yearlings in combination with older bulls in multiple sire settings. All young bulls should be observed at the beginning of the breeding season to determine that each bull is active and aggressive in seeking and mating females that are in heat. Even though young bulls have passed a Breeding Soundness Evaluation, this does not ensure that bulls have appropriate libido and the ability to breed in a pasture setting.

Dr. Gordon Jones retired in 2010 as professor of animal science after 40 years on the faculty at Western Kentucky University (WKU). During his tenure at WKU, he taught Introduction to Animal Science, Meats and Meat Products, Beef and Swine Production, and Animal Breeding. In addition, he was involved in the beef industry in KY and presented many programs on various aspects of the beef industry. Beef Cattle Selection and Mating Systems have been topics of major interest to Dr. Jones.

Jones served six years on the beef improvement committee of the Red Angus Association of America (RAAA), and he is currently a member of the technical committee of RAAA. Dr. Jones and his family have been involved in the swine seedstock business for over 50 years, and he is very involved with Red Hill Farms Red Angus and Simmental operations. He works with commercial producers in planning selection programs and crossbreeding systems.