When it comes to buying bulls, a diligent amount of time spent studying performance data, EPDs, pedigrees and other pertinent info is warranted as sire selection is the most important tool for making genetic progress in the herd. Of equal importance, however, is the care and management of the newly acquired bull, says Scott P. Greiner, Virginia Tech Extension animal scientist.

Greiner says proper management and nutrition are essential for bulls to perform satisfactorily during the breeding season. Particularly with yearling bulls, management prior to, during and after the first breeding season is particularly important, he says.

Prior to the breeding season. Many newly purchased yearling bulls are coming off a performance test that provided a high plane of nutrition, so their diet’s energy level should gradually be reduced to prevent excessive fat deposition. Do this by restricting intake of high-energy grain supplements, in conjunction with supplying a total diet lower in energy content (primarily forage), he says.

Young bulls should be managed to be a body condition score 6 at turn-out. This will give him adequate energy reserves for the breeding season. Yearling bulls can be expected to lose 100 lbs. or more during the course of the breeding season.

Acquiring a new yearling bull at least 60 to 90 days prior to the breeding season is critical from several aspects. First, this leaves ample time for the new bull to get adjusted to the feed and environment of his new home, as well as an opportunity for several new bulls to be comingled for a period of time prior to turnout.

Second, adequate exercise, in combination with proper nutrition, is essential to "harden" up these bulls prior to the breeding season. A facility for the newly acquired bull that allows for ample exercise will help create bulls that are physically fit for the breeding season.

A bull’s nutrition will be dependent on his body condition. Yearling bulls are still developing and should be targeted to gain 2-2½ lbs./day from a year of age through the breeding season. Bulls weighing about 1,200 lbs. will consume 25-30 lbs./day of dry matter. This intake may consist of high-quality pasture, plus 12 lbs. corn; grass legume hay, plus 12 lbs. of corn; or 80 lbs. of corn silage and 2 lbs. of protein supplement. Provide adequate clean water, and a complete mineral free-choice.

Prior to the breeding season, all bulls should receive a breeding soundness exam (BSE) to assure fertility. In fact, all working bulls should have an annual BSE. Because a variety of factors may affect bull fertility, it’s smart to retest young bulls before the breeding season even if it has only been a few months since their pre-sale BSE.

Management during the breeding season. Breed young bulls for a maximum of 60 days in order to prevent overuse, severe weight loss and reduced libido. Severe weight loss can impair future growth and development, and reduce his lifetime usefulness. When practical, supplementing young bulls with grain during the breeding season will reduce excessive weight loss.

In single-sire situations, young bulls can normally breed a number of females about equal to their age in months. Thus, a newly purchased, 18-month-old bull could be placed with 18 cows or heifers.

Bulls used together in multiple-sire breeding pastures should be of similar age and size. Young bulls can’t compete with older bulls in the same breeding pasture.

A common practice is to rotate bulls among different breeding pastures every 21 to 28 days to decrease the breeding pressure on a single bull. Some producers use older bulls early in the breeding season and replace them with young bulls.

The appropriate bull-to-female ratio will vary from one operation to the next based on bull age, condition, fertility and libido. Other factors include the size of the breeding pasture, available forage supply, length of the breeding season and number of bulls with a group of cows.

Observe bulls closely to monitor their breeding behavior and libido to ensure they’re servicing and settling cows. Additionally, observe the cowherd to monitor their estrous cycles. Many females coming back into heat may be the result of an infertile or sub-fertile bull. All bulls should be monitored for injury or lameness that may compromise their breeding capability.

Management after the breeding season. Following breeding season, young bulls need a relatively high plane of nutrition to replenish their condition and meet demands for their continued growth. Yearling bulls should be maintained in a separate lot from mature bulls, so these additional nutritional requirements can be provided.

The body condition and projected mature size of the bull will determine his nutrient requirements during the nine months following the breeding season. Be sure to isolate bulls from cows after the breeding season, and provide winter cover from extreme weather that may cause frostbite to the scrotum resulting in decreased fertility.

All herd bulls should receive breeding soundness exams (BSE) to assure fertility on an annual basis. Assess the bull battery well in advance of the breeding season, so that new herd sires can be acquired in a timely fashion.
-- Scott P. Greiner, Virginia Tech Extension