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Walk A structurally correct bull, when walking, will place his
hind foot in exactly the mark left by his front foot. If he is lame, or not moving freely, or if he is straight in his
leg structure, he will short-step and not reach his mark. Likewise, if he is sufering arthritis in one leg he may
tend to short-step or drag his leg on that side. Problems such as these will afect the serving ability of the bull.
5.3.4. Penis and Prepuce
The sheath and penis should be examined for abnormality or malfunction. The sheath should be trim and close
to the body. Loose and pendulous sheaths should be avoided and are often associated with increased risk of
injury or infection which can afect the functionality of the bull at mating Fig. 5.8.
Some bulls may show prepuce protruding below the end of the sheath. Although such bulls often have a
normal working life, they will be at increased risk of injury. A pendulous prepuce usually is indicative of a
weak retractor muscle.
Figure 5.7. Normal claw structure and examples of common faults. Source: NSW DPI.
Normal Large outside claw
and curled toe Scissor claw
Side
Sole
Front
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Beef Breeder MANUAL
Figure 5.8. Illustrations of a desirable sheath tight against the body - left image and an undesirable sheath loosely hanging - right image. Source: NSW DPI.
5.3.5. Scrotum and Testicles
Scrotal circumference is highly correlated to total sperm output and moderately correlated to normal
sperm morphology. Bulls with larger testes will produce increased daily and total sperm production. Testes size
and scrotal circumference is highly heritable. This means it is an easy trait to select for and rapid progress
can be made in selecting bulls that will also inluence age of puberty of his daughter. Bulls with genetically
larger scrotal circumference will produce daughters that reach puberty at a younger age. These females tend to
have better fertility throughout life. Thus, selecting bulls with genetically larger testes has positive beneits for
both the ability of the bull to sire calves, and the ability of his daughters to conceive and reproduce. The physical
scrotal size increases with improved nutrition and the bull’s age.
The testicles should be uniform, well-developed and properly balanced in relation to the age and size of the
bull. As bulls grow and mature their scrotum and testicles should be of a minimum size depending on their level
of nutrition Table 5.1. Bulls with scrotal circumferences smaller than the minimum will have reduced sperm
production and should not be considered for use in a breeding program.
Scrotal measurements are made by holding the neck of the scrotum with one hand, gently forcing the
testicles into the bottom of the scrotum, then placing a measuring tape around the widest point of the scrotum
Fig. 5.9.
Age months Minimal Scrotal Size
cm 12-14
32 15-20
34 21-30
35 30
36
Table 5.1. Minimum scrotal size for young, growing bulls to be considered for use in a breeding program.
Source: Coulter et al. 1987.Theriogenology. 27, 485-91.
Desirable sheath Loose, undesirable sheath
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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
