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There are variations in both normal and abnormal scrotal conformation. The testes and epididymis should
be palpated for size, tone, and symmetry and to make sure that there are no lesions on the epididymis. The
testes should be irm but not too soft or too hard. A symmetrical testes shape is normal and preferred. Any
deviation in size, shape, andor position should be viewed with suspicion.
Common scrotal faults include; • Extremely pendulous, soft or swollen testes
• Degenerative testes, penis and prepuce • Scrotum held in a tucked-up position
• “Tied” scrotum - where the attachment of the scrotum at the rear tends to hold it more horizontally
to the body. A bull exhibiting any of these problems should not be
used in a breeding program.
5.3.6. Semen Sample
A semen sample should be examined for the percentage of motile moving sperm, with 30 motile the minimum,
and for the percentage of normally structured sperm, with 50-70 normal being acceptable for multiple sire
mating, and 70 normal acceptable for single sire mating and artiicial breeding.
The two most common techniques of collecting semen samples are:
• Electro-ejaculation for semen quality testing; and • Artiicial vaginas AV’s, for collecting semen for
artiicial breeding. The electro-ejaculator technique is one of a gradual
build-up of electrical stimulation until the bull has an erection, protrusion of the penis and ejaculation.
It requires a skilled operator to stimulate ejaculation without unnecessary or excessive discomfort to the
bull during the procedure. Some bulls do not respond well to electro-ejaculation failure to get an erection or
to ejaculate, or unable to remain standing during the procedure, and in these circumstances an alternative
method is required. Manual massage of the prostate, ampullae, and seminal vesicles can also produce an
ejaculation, and this is a good alternative for bulls that do not respond to electro-ejaculation.
The collected semen sample is then examined usually on-site in the yards using a microscope to determine
sperm motility.
Figure 5.9. Measuring scrotal circumference on a young bull. Source: Future Beef.
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Sperm quality can vary from one test to another, even in healthy bulls. Nutrition, temperature, illness, time since
last ejaculation, bull age, and the proiciency of semen collection can all inluence the results of a semen
quality test. Bulls with low semen quality results should be tested a second time at a later date before being
permanently excluded from the breeding program.
5.3.7. Ability to Mate Serving Capacity
A bull must have both the physical ability and the desire to mate with cows in order to be useful in a breeding
program. All bulls being considered for use must demonstrate the ability to mount, position themselves,
direct their penis into the cow, and ejaculate. Observing a bull while in the company of a cycling cow will quickly
reveal if he has any basic interest in mating, and whether he is capable of successfully mating.
Most bulls naturally exhibit a strong desire to mate with cows that are cycling, so it is usually the ability to
mate that is of most importance in a serving capacity test. The most common problem likely to be observed
is failure to align the penis with the vagina. Deviation ‘corkscrewing’ of the penis, or a loose, swinging sheath
may make alignment diicult, and bulls with these characteristics should not be considered for use in a
breeding program.
5.3.8. Bull Management and Preparation for Mating
