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COW/CALF CORNER
The Newsletter
From the Oklahoma Cooperative Extension Service
March 23, 2007
In this Issue
Bull Breeding Soundness Exams, Do They Cost or Pay?
by Dave Sparks, DVM, OSU Area Extension Food-Animal Quality and Health Specialist
The Components of a Proper Breeding Soundness Exam
by Dr. Glenn Selk, OSU Extension Cattle Reproduction Specialist
Bull Breeding Soundness Exams, Do They Cost or Pay?
by Dave Sparks, DVM
Today lets look at three popular misconceptions about bull breeding soundness exams. The first is the idea that “He’s been getting calves for several years, why would he have a problem now?” Things change. Bulls get infections, tumors, and injuries, all of which can reduce their effectiveness. Even just advancing age can lower a bull’s fertility level. The second thought is “This young bull just came from a production sale and he was guaranteed.” Many bull sellers guarantee their bull in lieu of testing, not after testing. He might be guaranteed, but this isn’t much help if you are not aware of a problem until next fall when you pregnancy test. In addition, if you don’t get back to the seller until you know you have open cows, he may not honor the guarantee. He may feel that the problem is due to something that happened in the several months that the bull was in your possession. He sure isn’t going to assume the liability for your open cow problem. Have new bulls tested soon after you get them home. The third misconception is that the purpose for checking bulls is to eliminate sterile bulls. There are not very many sterile bulls, but there are a lot of bulls with reduced fertility.
Bulls which do not settle their fair share of calves early in the season are contributing to poor reproductive efficiency. This can be even more costly than dead calves, although not as dramatic. A 21 day delay in breed back time costs you 35 pounds of calf at weaning time. With today’s prices that can mean $50.00. When you have several cows that conceive two or three heat cycles behind their optimum time, you have a significant loss of income, even though the costs to keep, breed, and feed that cow are the same. Once a cow becomes a late calver, there is probably never going to be anything you can do to catch her back up, so she will wean young, light calves every year. You work hard to make your cows profitable, make sure the bull is not stealing from you through reduced fertility.
The Components of a Proper Breeding Soundness Exam
by Glenn Selk
For the breeding soundness evaluation to be successful, bulls should be evaluated 30 to 60 days before the start of breeding. It is important to allow sufficient time to replace questionable bulls. Bulls should also be evaluated at the end of breeding to determine if their fertility decreased. A breeding soundness exam is administered by a veterinarian and includes a physical examination (feet, legs, eyes, teeth, flesh cover, scrotal size and shape), an internal and external examination of the reproductive tract and semen evaluation for sperm cell motility and normality.
The physical examination studies overall appearance. Flesh cover is one factor to evaluate. Body condition can be affected by length of the breeding season, grazing and supplemental feeding conditions, number of cows the bull is expected to service and distance required to travel during breeding. Ideally, bulls should have enough fat cover at the start of breeding so their ribs appear smooth across their sides. A body condition score 6 (where 1 = emaciated and 9 = very obese) is the target body condition prior to the breeding season.
Sound feet and legs are very important because if they are unsound, this can result in the inability to travel and mount for mating. The general health of the bull is critical since sick, aged and injured bulls are less likely to mate and usually have lower semen quality. The external examination of the reproductive tract includes evaluation of the testes, spermatic cords and epididymis. Scrotal circumference is an important measure since it is directly related to the total mass of sperm producing tissue, sperm cell normality and the onset of puberty in the bull and his female offspring. Bulls with large circumference will produce more sperm with higher normality and also reach sexual maturity sooner.
Examination of the external underline before and during semen collection will detect any inflammation, foreskin adhesions, warts, abscesses and penile deviations. The internal examination is conducted to detect any abnormalities in the internal reproductive organs.
The semen evaluation is done by examining a sample of the semen under a microscope. The veterinarian will estimate the percentage of sperm cells that are moving in a forward direction. This estimate is called "motility". In addition, the sperm cells will be individually examined for proper shape or "morphology". Less than 30 percent of the cells should be found to have an abnormal shape.
Any bull meeting all minimum standards for the physical exam, scrotal size and semen quality will be classed as a "satisfactory" potential breeder. Many bulls that fail any minimum standard will be given a rating of "classification deferred."
This rating indicates that the bull will need another test to confirm status. Mature bulls should be retested after six weeks. Mature bulls will be classified as unsatisfactory potential breeders if they fail subsequent tests. Young bulls that are just reaching puberty may be rated as "classification deferred", and then later meet all of the minimum standards. Therefore caution should be exercised when making culling decisions based on just one breeding soundness exam.
Many producers work hard to manage their cows for high fertility. They may assume that the bulls will do their expected duties. However, it's important to pay close attention to bulls to establish successful breeding.
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