Bull Breeding Soundness Examination


The Bull BSE form

copyright from the Society for Theriogenology

Click to enlarge sample

  • The first question we should ask is 'Why do a bull BSE?' 
    • Economically, it has been shown to pay a $17.00/cow (1970s dollars) return on the BSE the investment of bull BSE. 
    • That is $17/cow, not per bull. 
    • If you figure that a bull is usually exposed to about 30 cows.....do the math.
  • When do you want to do a bull BSE? 
    • A bull BSE should be performed before purchasing a bull, if fertility problems are a concern, or 30 -60 days prebreeding.
  • If you use the SFT BSE form you have more legal history behind you than the system you 'invent'.
  • In most cases we must rely in the producer's observation for libido, mating ability, and social dominance. If the bull will not find cows in heat, will not mate or is dominated by other bulls, then even if he passes a BSE it matters not. Performing libido testing and mating ability is a difficult and time-consuming task, so it is usually not incorporated into most routine bull BSEs.
Physical examination
  • Identification of the bull is essential. Obviously a hide brand, or ear tattoo is better than ear tags for positive identification. If you have a controversial case, take a photograph.
  • A physical exam is important in determining if a bull will be able to adequately breed. A bull's body condition must be good at the BSE, because a bull will lose condition during the breeding season. If he starts too thin, he may not be in good enough condition later on to breed cows.
  • The bull's locomotion system must be good as he needs to get to cows to breed them. Poor conformation can contribute to lameness, which obviously contribute to breeding problems.
  • Test the bull's vision, as bulls identify estrual cows by sight, not by smell. If a bull cannot see, he will not find the cows in estrus.
  • Look at the teeth. A bull needs to eat in order to stay fit enough to breed. You can also age a bull by his teeth.
  • Look carefully at the sheath for its conformation. It should basically point at the ground between the bulls front feet (except for the last bit on the tip). Check it carefully for an abscess, eversion, or prolapse. If these conditions appear during a BSE, the bull will probably not last the breeding season.
Poor preputial conformation (left) and good conformation (right).
Libido testing
  • Libido testing is not routinely performed when doing a BSE.
  • The 'one bull method' has a restrained heifer and you allow the bull 10-15 minutes to mount the heifer. A bull should mount at least once. If he does not mount, he should fail and be tried again.

  • The 'multiple bull method' used 4 heifers on a pen perimeter, with 5 bulls turned in with them. Each bull should serve at least 3 times in 40 min. As they breed you can remove those that do breed to allow the others more chances to breed without any bull dominance affecting the breeding performance.
  • When the bull is being ejaculated, make sure he can fully extend his penis. Phimosis is when the bull cannot get the penis out, and paraphimosis is when the bull cannot get the penis in.
  • During ejaculation check for a persistent frenulum. This occurs when the prepuce remains attached to the glans penis. It may be a heritable condition, so it is best not to keep bulls that have it.

  • An adequate length for a bull's penis is that it should come almost between the front legs during a full erection and extension. A bull with a too short penis will not be able to breed.
  • Other penile problems such as deviations of corkscrew, rainbow, or lateral deviations should be noted and will cause a bull to fail a BSE.
  • A fibropapilloma on the bull's penis may cause hemorrhage during breeding, and result in infertility.
  • The testes should be examined for carriage, consistency and size.
  • The shape of the scrotum is important for thermoregulation of the testes. A 'neck' should be present in the scrotum, but abnormal shapes include scrotums that are pointed or straight sided.
  • The testes should be freely moveable within the scrotum and the testes should be symmetric. The testes may rotate 40 degrees normally and the 'scrotal ligament' may cause the testes to be pulled dorsal and caudal, but this has little apparent affect on fertility.
  • Any testicular asymmetry is abnormal and may indicate orchitis, testicular degeneration, hydrocele, or hernia. The testes should have the consistency of a flexed biceps muscle.
  • The size of the testes is correlated with sperm production in the bull and age of puberty in the offspring.
  • It is also important to palpate the epididymis to ensure that it is present and it is normal.
  • Scrotal circumference is an indirect measure of testicular mass, it is associated with sperm production, and it is associated with parenchymal health of the testicular tissues. Bulls with small testes produce less sperm, have a later puberty in their daughters and sons and have earlier testicular degeneration.
  • The scrotal circumference is measured at the widest point of the scrotum, being careful to pull the testes down into the scrotum and to keep the testes together. Errors can be made if fat is in the scrotum, a hernia is present, hydrocele is present or the testes are pushed apart when the measurement is made.


Internal accessory glands

Bull palpation
  • The prostate is palpated as a band that crosses the pelvic urethra.
  • There are no diseases associated with the prostate, but it is a useful landmark.
  • The ampullae is the distal portion of the ductus deferens that connect to the pelvic urethra. There are generally no problems with this accessory sex gland.
  • The seminal vesicles are paired glands that feel like a bag of grapes on either side of the pelvic urethra. Seminal vesiculitis is a fairly common disease of bulls. Any asymmetry or pain associated with palpation is an indication that vesiculitis may be present.
  • The inguinal rings should be palpated. They are normally about a hand's width off the midline and a hand's length over the brim of the pelvis. You can usually just get your fingers into the rings. If the rings are large, or a loop of intestines is going through the rings, the bull may have problems in the future.

Stallion - Bull is similar

Semen collection
  • An artificial vagina (AV ) is the ideal method to get a physiologic semen sample. Unfortunately this can only be used on trained bulls.
  • The electroejaculator is the most commonly used method to obtain a semen sample. 
    • The mild electrical stimulation stimulates sympathetic and parasympathetic nerves to cause ejaculation, however it is not a physiologic sample that is collected. 
    • The electrodes should face ventral
    • You can dilute sample by excess collection of vesicular fluid. 
    • Some bulls do not respond well and some bulls go down (Brahman) with the stimulation. 
    • The technique is one of a gradual build-up of electrical stimulation until the bull has an erection, protrusion of the penis and ejaculation. 
    • Some machines are manually operated and some are preprogrammed to deliver the correct stimuli.
      • You start with a low 'power' setting and then work the 'power' up until erection, protrusion and ejaculation. 
    • In cold climates the collection cup ('loving cup') is insulated with a warm water jacket.

Semen Collection using an electroejaculator. 

Electroejaculators. On the on the right an 'automatic' machine. 

  • Manual massage of the prostate, ampullae and seminal vesicles can also produce an ejaculate.
    • This is a good alternative for bulls that go down on electroejaculation. 
    • You can massage the seminal vesicles to produce an erection and the ampullae to produce ejaculation. 
    • This is not possible in all bulls however.
  • Is it painful?
    • Vocalization has been deemed to be an indicator of pain, so apply electrical stimulation as carefully as possible
    • Local anesthesia has not shown to be effective at eliminating vocalization
  • Why do we use it?

                              Semen Evaluation

                     Evaluation system for BSE:

  • The following criteria are used to standardize BSE among veterinarians in North America and to provide a more legally acceptable set of standards to compare bulls.
  • In order to pass a BSE a bull must have a normal physical examination must meet minimum requirements for scrotal circumference, sperm motility and sperm morphology. These criteria are relatively easy to test and are easily repeatable.
  • A bull must have > 30% individual motility to pass. Motility is the most lenient criteria, as it can be influenced by semen handling to a great extent.
  • The sperm cell morphology must have > 70% normal to pass.
  • The scrotal circumference must meet minimum criteria for individual ages.
  • A bull must meet these minimum criteria in each category to pass a BSE.
  • The final classification can be:
  • Satisfactory - the bull passed all 3 criteria and should be a good bull.
  • Deferred - the bull did not pass all criteria, but should be reevaluated, because you feel the problem may resolve over time.
  • Unsatisfactory - the bull does not pass all criteria and has non-resolvable problem.
  • The examiner holds the final diagnosis and may fail a bull for any valid reason. Any problem can fail bull.
  • do a complete physical
What a BSE is not !!!!
  • It is not indicative of relative fertility. It cannot rate a single bull better or worse than another individual. It is designed to identify groups of bulls that are more or less fertile than other groups of bulls.
  • No libido testing is generally done.
  • Mating ability is not determined.
  • Venereal diseases are usually not checked, because a single negative sample is meaningless.

Other available fertility evaluators

Fertility Associated Antigens

  • Presence allows increased acrosome reaction 
  • More fertility from bulls that have it
  • Do non fertile bulls have it?


Bull Infertility
Congenital infertility

Testicular hypoplasia
  • The sperm cells fade at the primary spermatogonium stage. It is seen in Swedish red and white bulls.
  • Segmental aplasia of the epididymis. The epididymis is absent, so cells cannot get from the testes to the penis.

Short penis
  • This is a heritable and can cause infertility because of the difficulty the bull has breeding.
  • A bull should be able to almost extend the penis between the front legs. 

Persistent penile frenulum
  • The frenulum usually separates by 32 weeks.
  • The band on ventral aspect from the penis to the prepuce persists.
  • The ligament can be cut and ligated, but it is recommend against breeding these animals.

Short retractor penis

  • The short retractor penis prevents penile extension.
  • Diagnosis is by feeling a tight band at erection where the retractor penis muscle is.
  • A short unilateral retractor penis results in a bulge unilaterally by the scrotum on erection.

Penile deviations

A corkscrew or lateral deviation at breeding.

  • You cannot diagnose a corkscrew penis when electroejaculating a bull.

Acquired diseases Seminal vesiculitis
  • The clinical signs are pus in semen, painful vesicular glands, enlarged glands, and firm glands.
  • The cause may be a congenital and inherited problem in the colliculus. This allows ascending infections access to the seminal vesicles.
  • It may be seen in young, grouped bulls.
  • Actinomyces pyogenes is the most common isolate in individual cases, but
  • Brucella, E. coli, Pseudomonas, Strep, virus, mycoplasms, ureaplasms have been isolated.
  • Diagnosis is made by seeing pus in the semen, enlarged glands, and possibly by culture of the vesicular fluid. Culture should be done by placing a catheter up to the seminal vesicles and collecting pure vesicular fluid. Semen cultured at ejaculation may always contain contaminants.
  • There is little effective treatment, particularly in older bulls.
  • The disease usually becomes chronic and treatment by antibiotics is usually not successful.
  • Surgery, removal of the seminal vesicles may be tried as a last resort, but success is not likely.
  • These bulls should probably be culled as the condition may be hereditary.

Testicular degeneration
  • In testicular degeneration the testes were once normal, but now the germinal epithelium is gone.
  • The testes have a very limited response to any injury. Meiotic cells (prim. spermatocytes) are affected the most. The spindle formation is disturbed and results in major damage. Mitotic cells are less affected (the A,and B spermatogonium).
  • With a mild injury the cells divide, but the nuclei are unequal, so you get head abnormalities. You see poor motility and proximal drops.
  • With moderate injury you see premetaphase damage, so the spindle is disrupted earlier and the result is chromosome lysis. You see few cells, poor motility, proximal drops, and nuclear craters.
  • With severe injury there is metaphase interruption and the chromosomes condense, with the result being
  • Giant cell results, and 'restitution' cells. In these cells the chromosomes divide, but the cell does not. This results in a chromatin rich cell and indicates that the point of no return has been reached.
  • The diagnosis is made by a history of once being normal and now having few to no sperm cells.
  • The cells seen in the ejaculate are indicative of degeneration and include restitution cells and giant cells.
  • A biopsy reveals a thickened Basement Membrane, and only Sertoli cells.
  • Reexamine in 60 days
  • Hypoplasia predisposes
  • Decreased gonadotrophins
  • Orchitis, periorchitis
  • Causes of degeneration include:
    • Strain 19 vaccine, 
    • fever, 
    • autoimmune, 
    • chemicals, 
    • Cadmium, 
    • fluorinated napthalenes, 
    • griseofulvin, 
    • EtBr, 
    • toxemias, 
    • high Estrogen, 
    • exogenous Estrogen, 
    • Testosterone, 
    • aging,
    •  twinning (freemartin), 
    • chromosome abnormalities, 
    • pampiniform phlebitis, 
    • frostbite on the scrotum, 
    • environment (heat stress), 
    • inguinal hernias, 
    • scrotal fat, trauma, 
    • tumors, 
    • testicular biopsy, 
    • stress, starvation, 
    • radiation
    • laying down excessively (this increases scrotal temperature).
  • To treat degeneration you must first remove the problem.
  • Cool water hydrotherapy and sexual rest are also indicated.
  • NSAIDs are also indicated.
  • You should recheck the bull in 60 days, after a complete cycle has been completed.

Testicular ultrasound
  • The parenchyma has a homogeneous ground glass appearance. The mediastinum testis is an echogenic line in the center of the testes.
  • The tunics are seen as an echogenic line closely applied to the testes. You only see one unless there is a hydrocele, which will be seen as a fluid density (black) between the tunics.
  • The epididymis has a 'moth eaten' appearance.
  • Fibrotic foci do not adversely affect breeding soundness.

contributed by Bruce E Eilts and modified on 23 Ocober-05 

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contributed by Bruce E Eilts on 25 September 2012


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