Finally, the semen sample is evaluated for morphological
abnormalities. This is done by looking at a small amount of
semen under the microscope and counting out at least one
hundred sperm cells. The cells are classified as either
normal or abnormal. Two types of abnormalities exist
(Figure 1). Primary abnormalities are abnormal heads, mid-
pieces, or tightly coiled tails. Secondary abnormalities
include defects such as bent tails and distal droplets. There
is evidence that a bull's fertility can be effected when sperm
cell abnormalities exceed 25%.

Figure 1.

 SEMEN MORPHOLOGY






Normal Spermatozoan

Coiled Tail and Midpiece

Distal Droplets _


score in this category would be given to a semen sample
with less than 10% primary abnormalities or less than 25%
total abnormalities. The final 20% of the BSE score is allo-
cated to the semen motility. The gross motility of the sample
or sometimes the movement of individual sperm cells is
evaluated and a score assigned according to the vigor of
movement noted.

 Another characteristic that should be evaluated by the
producer is a bull's libido, or sex drive. The libido of a bull
can be tested by placing the bull in a small pen with several
females that are in standing heat. The bull should attemptto
mount a female within 2-5 minutes. A close observation of
the bull and his behavior in this situation will help the pro-
ducer identify any physical problems the bull might have.
Bulls that exhibit high libido settle more cows earlier in the
breeding season. However, there is no relationship
between libido and testicle size. A bull with large testes and
acceptable semen quality may have poor libido, thus
causing a low pregnancy rate in the group of females that he
is servicing.

 The University of the Virgin Islands, Agricultural Experi-
ment Station on St. Croix is currently conducting research
on the effects of season on local Senepol and Holstein
cattle. Results from this research are forthcoming. N


 Breeding Soundness is then scored by assigning point
values to the various factors in the test (Table 3). Scrotal
circumference is worth 40% of the total score. The points
assigned to the scrotal circumference depend not only on
the measurement but also on the age of the bull. Semen
morphology is also worth 40% of the total score. A perfect

 Table 3. Scoring Criteria for Breeding Soundness Exam (BSE)


 Scoring Criteria Very Good Good Fair Poor

 Scrotal Circumference (cm)
 (Mature Bulls) > 39 34 39 < 34 < 34

 Score for Scrotal
 Circumference 40 24 10 10

 Semen Morphology (%)
 Primary Abnormalities < 10 10 19 20 29 > 29
 Secondary Abnormalities < 25 26 39 40 59 > 59

 Score for Morphology 40 24 10 10

 Motility Rapid Moderate Slow No

 Score for Motility 20 12 10 3