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'STRINGEEBULLSFOR flitEEI DfU1(1EN!ub SU DNESS
CHARLES B. PLUMMER, JR.
Agricultural Extension Service Veterinarian
ALVIN C. WARNICK
Agricultural Experiment Station
UNIVERSITY OF FLORIDA
AGRICULTURAL EXTENSION SERVICE
Purpose.-This test is to give the cattleman
reasonable assurance that the bulls to be usee
during the coming breeding season will settle
50% or more of his cows on first service if bre(
to potentially fertile brood cows. This test wil
help the cattleman cull those bulls that are poo:
potential breeders and help improve his calf cro]
and shorten his breeding season.
Evaluation Based on Semen
Quality and Physical Traits:
Bulls rated satisfactory must meet certain
minimum standards in both semen quality an(
physical traits. Even though a bull has a satis
factory semen score but is blind or has a broke]
penis, he would not be classified as a potential!
satisfactory breeder for natural breeding. B:
the same token, a bull that has very satisfactory.
physical traits but has a very low semen score
would not be a potential breeder.
Method of Evaluation:
Semen collected by any artificial method i
evaluated by examining the sperm cells, usinj
the following criteria:
1. Vigor (movement).
2. Concentration (numbers).
3. Morphology (shape-normal or abnormal
4. Percent alive.
Each of the above is given a numerical score
based upon microscopic and gross examination:
Bull testing is another tool that can be used
by cattlemen to eliminate unsatisfactory bulls
that have little or no chance for settling cows.
The test is not designed to put emphasis on small
differences that may exist in the potential fertility
of bulls classified as satisfactory for use in natural
It should not be assumed that a bull with a score
of 90 to 100 would necessarily be a better pros-
pective breeder than one with a score of 60, 70
or 80. On the basis of present knowledge an
techniques of semen evaluation, we do not believe
that differences in dollar value for natural breed
ing can be assigned to 2 "satisfactory" bulls, on
of which has a higher score than the other.
COOPERATIVE EXTENSION WORK IN
AGRICULTURE AND HOME ECONOMICS
(Acts of May 8 and June 30, 1914)
Agricultural Extension Service, University of Florida,
Florida State University and
United States Department of Agriculture, Cooperating
M. O. Watkins, Director
It's Performmane that counts!
ig soundness SEMENQUALI TY
PH SIA TRAIT
nd when added together they make up the total
Physical traits include an examination for:
1. General condition.
2. Legs and feet
3. Age and teeth.
5. Reproductive organs.
6. Diseases and parasites.
7. Miscellaneous defects. '
Classification of bulls:
3. Culls or unsatisfactory.
Bulls in this group are physically fit, have a
emen score of 60 or above, and are considered
o be capable of settling, on the first service, not
ess than 50% of the fertile cows to which they
Bulls are placed in this classification for one or
aore of the following reasons: (1) Question as
o whether a truly representative sample of se-
nen was collected; (2) questionable repairable
physical defects; (3) semen scores between 40-
Bulls in this group may be expected to settle a
ew cows, but the conception rate would probably
fall below 50% on the first service. Tey lay
change, for better or worse, at a later:. ie, and
should be re-checked at the discretioniobf the owner
Bulls in this group have a semen score of less
than 40 and obvious physical defects with little
or no chance for recovery.
Time for Testing Bulls:
Bulls should be tested just before the beginning
of the breeding season. However, for various
reasons, the rancher may want to check at other
times. Yearling bulls may be checked, but often
the semen score will be low due to sexual imma-
turity. Young bulls will generally score higher
with increasing age.