Bull breeding soundness evaluations are quick, economical screens of breeding potential used to determine the bull’s physical preparedness for breeding.
By: Sandy Stuttgen, University of Wisconsin Extension
Outcomes are best used to identify infertile or sub-fertile bulls rather than superior ones. The diagnosis of ‘satisfactory’ does not attempt to predict fertility as the evaluation is only a snap shot view of the bull on a given day and time.
During a breeding soundness evaluation, the clinician is checking off and measuring a systematic list of physical attributes regarding the internal glands, testis, penis, spermatozoa and overall physical exam:
- note bull’s identity, age, breed, owner
- pelvic palpation: ampullae, prostate, vesicular glands, inguinal rings for gross abnormalities
- observe and palpate testes/epididymides/scrotum for condition/abnormalities
- measure scrotal circumference: 30 cm is the minimally adequate size, regardless of breed
- observe and palpate penis for presence of a persistent frenulum, penile hair ring, warts or other penile abnormalities
- collect sperm to observe and measure motility: minimal threshold is 30% gross motility
- observe and measure sperm morphology: at a minimum, 70% must be normal
- observe and measure presence abnormal cells present (pus, blood) in the ejaculate
- observe overall body condition; feet, legs; eyes
At the conclusion of this evaluation, the clinician completes a record of all findings, interpreting the data to indicate the bull on this date as one of the following:
- satisfactory potential breeder
- classification deferred to another time, additional tests or another clinician
- unsatisfactory potential breeder
Clinician competency and consistency factor into the evaluation. Confidence, accuracy and speed come with experience and using proper equipment. Ejaculations should be done in a humane manner, working with the bull to collect a sample and promptly examining that sample using a good quality microscope. Sperm morphology is best measured after staining the sample and then observing at 400x magnification with oil immersion.
Some of the mentioned abnormalities, for example warts, persistent frenulum and hair rings, can be easily fixed during the evaluation. Small penile warts can be excised with a surgical scissors or scalpel blade and topical medication applied. Larger lesions can be surgically removed using local anesthesia and suturing. The bull would also need to be given wart vaccine and sexual rest; re-evaluating in 3 weeks for the presence of new warts. If no new growths occur, the bull should be ready for service at that time.
The skin of the penis and prepuce of bulls are fused at birth, becoming separated as puberty is reached (8-11 months old). The frenulum is a fine band of connective tissue that extends from the prepuce to the near tip of the glans on the ventral (bottom) aspect of the penis. The frenulum normally breaks free during separation of the penis and prepuce. Failing this, a persistent frenulum occurs, which causes a ventral bending of the penis during erection. The condition is usually noticed at first breeding, and sometimes the bull will breed in spite of it, which can lead to tearing and inflammation as the erection forcibly ruptures the frenulum. When found during the soundness evaluation, the frenulum can be simply snipped or manually freed, after which the bull should be ready for breeding service in 2 weeks.
Body hair from females being ridden, or other males ridden during homosexual activity (especially seen in young bulls), can accumulate and encircle the penis of the aggressor bull and form a firm band when the penis is retracted into the prepuce. The hair ring may lead to pressure necrosis of the urethra, and avascular necrosis and sloughing of the glans penis. It is a simple matter to snip the hair off during the soundness evaluation. Antibacterial ointments can be applied if warranted.
Abnormalities of the pelvic accessory sex glands and questionable semen morphology and motility lead to more advanced discussions with the veterinarian making the determination. Yearling bulls or the first collection of the year, sometimes provides a sample that does not pass. Retesting is a couple days or so can often get the “plumbing” cleaned out.
Bulls are more than their reproductive apparatus. They must be regarded as sexual athletes physically able to see and mount cows. Body condition, feet and leg (lameness and conformation issues) and eye conditions can be diagnosed and remedies decided upon. Other overall health considerations such as vaccination and de-worming history can be discussed and acted upon.
Calling a bull ‘satisfactory’ or ‘sound’ during a breeding evaluation cannot guarantee eventual pregnancy outcomes as the bull’s libido, nutrition (what he eats has a huge impact for his overall performance), social status (bull to female ratio and use of multiple sires in a herd) and environmental conditions (hot summer/muddy or otherwise poor footing) during the actual mating season are not measured on this day and time. Tests for venereal or other diseases are generally not conducted at this evaluation. The female side of the equation is also not being evaluated.