Are They Ready?

Evaluating bulls before breeding season pays big dividends.

By Sandy Johnson, Kansas State University Northwest Area Livestock Specialist

As the breeding season approaches it is important to remember the importance the bull plays in a successful calf crop. Since each bull will breed many females, a bull fertility problem can have widespread effects. In preparation for the upcoming breeding season, plan to ensure that bulls are in appropriate body condition, in good physical shape and that each bull has passed a breeding soundness exam (BSE) 30 to 60 days before turn out.

According to the 1997 NAHMS survey on use of reproductive technologies, 40 percent of producers use a BSE to evaluate bulls prior to turn out; the other 60 percent must like to gamble. Estimates from Colorado and Texas indicate that 1 of 5 bulls receive a score of questionable or unsatisfactory in the BSE. Lower than normal temperatures this past winter may have increased the incidence of frostbite to the scrotum. The resulting damage may be temporary, or in more severe cases, cause permanent sterility.

Since the outlook for calf prices is strong for this next calf crop, a BSE is an excellent investment. A breeding soundness exam consists of a physical examination, an exam of the reproductive organs, a scrotal circumference measurement and semen evaluation. Checking feet and legs, body condition score, eyes and teeth assesses the bull's physical condition.

Anything that would reduce a bull's ability to find cows in heat and successfully service them should be noted. The reproductive tract is thoroughly examined internally and externally for injuries or abnormalities. Scrotal size is measured because it is highly correlated with daily sperm production. A sample of semen is also collected, and the concentration, motility and morphology of the sperm cells are evaluated. Each portion of the BSE is important, and attention to detail at each step will ensure that subfertile bulls are identified.

The BSE doesn't test the bull's libido or willingness to breed and -- contrary to popular belief -- there does not seem to be any good visual indicator of bull fertility or libido. Serving capacity or libido tests can be performed, although few breeders use them because of the time and expense the test requires.

If you purchased a yearling bull to use this season, keep in mind that these bulls are still growing and should be on a diet that will allow them to continue to gain weight but not become too fat. A highly fit or conditioned bull should gradually have the amount of concentrate in the ration reduced. This change should occur gradually since dramatic changes in nutrition can affect semen production.

If is common for young bulls to lose more than 100 pounds during the breeding season, so they should have some energy stores going into the season. A 12 percent CP ration consisting of 80 percent hay and 20 percent concentrate (about 6 to 10 pounds of grain) should allow young bulls to grow but not become over conditioned. Promote exercise by placing bulls in a sizeable pen, and place water and feed at opposite ends.

Two-year-old bulls should also gain weight prior to the breeding season to ensure adequate energy reserves. For older bulls, the target energy level will depend on their body condition. If bulls have wintered in good body condition, five to seven pounds of grain may be adequate to build the desired energy reserve. When feeding a group of bulls, adequate bunk space is essential.

Vitamin A is necessary for optimum semen production and -- given the lack of green forage in some parts of the High Plains the past 12 months -- individual animal stores may be rather low. An injection of Vitamin A is inexpensive and would ensure that stores are replenished. Vitamin A can be delivered in minerals or supplements, but with the depletion that may have occurred with the drought, that method may be too slow.

A fertile, active bull is critical in getting the majority of cows bred early in the breeding season. Make sure to take the time to have a BSE performed and to get bulls in proper condition before breeding season.