Clinical Examination of Farm Animals - CYF MEDICAL DISTRIBUTION

CHAPTER 11
Outer case
Rubber band securing liner
Reflected liner
Cone
Access for
warm water
Semen
collection
tube
Figure 11.9 Artificial vagina for semen
collection from the bull.
amount of water in the AV should be checked and
adjusted as necessary. A very brief visual inspection
of the penis can be made as it is extruded from the
prepuce and before it enters the AV. Gross abnormalities,
such as severe injury or blood loss, may be observed
but will require more careful examination.
The semen sample must be kept warm and examined
as soon as possible. Semen volume, density
and motility are determined immediately. A drop of
semen is placed into eight drops of nigrosin–eosin
stain, and smears are made to enable the percentage
of live, normal, and live and normal sperm to be determined.
The smears are examined microscopically
using an oil immersion lens. Dead sperm take up the
nigrosin–eosin stain; living sperm do not. Sperm
defects, such as detached heads and coiled tails, are
identified and counted by direct observation.
Normal semen parameters in the bull
These are given in Table 11.2; slight variation from
the reported parameters is acceptable, and some
bulls of proven fertility may have, for example, low
sperm density. Wherever possible, high standards of
semen quality are desirable.
(5) Further diagnostic tests
Blood sample
A blood sample may be taken to check whether the
bull has been exposed to infection by such organisms
as IBR/IPV/IBP virus. Antibody and antigen tests
are taken for diagnosis of bovine virus diarrhoea
(BVD) infection.
Table 11.2 Normal semen parameters in the bull
Parameter
Value
Volume (ml) 5–10
Density (sperm/mm 3 ) 0.5–1.5 ¥ 10 6
Live sperm (%) 75
Normal sperm (%) 80
Live and normal sperm (%) 75
pH 7
Motility >3 (range 0–5)
Progressive motility (%) >80
Methylene blue reduction time (min)