Developing Young Bulls

Postweaning development of bulls 8 to 10 months of age plays an important role in their potential ability as future herd sires. Their usefulness as yearling bulls depends to a large extent on how they are handled from weaning until the onset of the breeding season. From weaning to three years of age, bulls should be separated by age. Weaned bulls should be dewormed, defluked (if flukes are a problem in your area), and vaccinated for 5-Way Leptospira, Campylobacteriosis (Vibriosis), and Trichomoniasis (Trich), according to the disease incidence in your region. Your veterinarian is a good source to determine the diseases that are present in a particular area. In addition, bulls should test negative for brucellosis (Bangs) and tuberculosis (TB). Healthy bulls should then be developed to attain adequate growth and size so that their inherited characteristics for production can be determined. To insure adequate growth in the year following weaning, bulls of British breeding should gain at least 2 pounds daily, while bulls of the larger breeds should gain an additional 1/4 pound per day. The practice of feeding high energy concentrates to young bulls in dry lots or commercial tests to attain maximum gains of 3 to 5 pounds daily, when these bulls are to be used as yearlings in the breeding program, has been questioned due to the association of excessive fat cover with reduced fertility andsoundness problems. Recent reports from the University of Tennessee, however, indicate there is not a relationship between excessive backfat and low-quality semen as previously thought. Therefore, bulls that are raised on high energy diets should be acclimated to pasture prior to the breeding season. Commercial bulls in the Southeast are primarily developed by maximizing the use of forage grazing with limited use of concentrate feeds.

Bulls gaining 2 pounds per day from weaning should weigh over 1250 pounds at 18 to 20 months of age. Rations used to achieve this level of production should be 65 percent TDN (total digestible nutrients) and 10 to 12 percent crude protein. One will need to feed about 2 1/2 to 3 percent of the bull's body weight per day. A recommendation can be given to the self-feeding of high quality forages and a concentrate supplement equal to about one percent of body weight per day. A complete trace mineralized salt and a balanced Ca and P mineral mix, which should be at least 0.41% Ca and 0.21% P for lighter bulls and decrease as bulls become heavier, should be provided free choice at all times. The quantity and type of supplemental feed needed depends on the season and the quality of the base forage provided.

Source:

Development and Management of Bulls

EDITED BY J.W. Lemaster and R.S. Sand