Sheep - AgRIS

animal in an extended position on a table. The rectal probe is lubricated, moistened and inserted
so that last ring is located just inside the rectum. The penis may be gently pulled out before
stimulation. But on many occasions it generally protrudes with stinulation. The end of the penis
should be held in a glass vial or a test tube. During the prcess the voltage is gradually increased
and then reduced to zero during a five second period followed by an equal period of rest.
Stimulus is gradually increased until the semen is ejaculated in the order of 2,5, and 8 volts.
The number of stimuli necessary to produce semen is variable.
Collection of semen by the A.M is considered as the best method. Collection by electrical
stimulation has an advantage that training of the rams is not necessary. When a large number of
rams are to be tested for semen quality, collection by electrical stimulation is advantageous.
The major disadvantage in the electrical stimulation is the likely injury to the animal which can
be minimised by the use of the bipolar electrode. Other disadvantages are: Slightly lowered
spermatozoal density; the possibility of contamination of semen by urine; difficulty in
obtaining second collection within short time if the first one is not satisfactory and the
refractoriness on the part of some rams.
Experience shows that by collection in artificial vagina the volume of one ejaculate is
smaller but denser as compared to an collection by electrical method. High quality of ejaculates
is the main advantage in collection of semen by artificial vagina.
7.2.2.3 Semen Volume
The number of collections to be obtained in a day varies from ram to ram. From most of
the rams semen can be collected three times a day producing average ejaculates of 1.0 ml,
sperm concentration of 35 x l0 8 per ml and live counts 85-90% Semen could successively be
collected up to 5 times daily for 17 days from mature rams without fall in semen quality
(Miller, 1975). He further reported 15,000 x 10 6 sperm per day from two teeth rams in three
collections (Table 7.1).
Table 7.1 Results of rams semen examined on day 6th and 15th day of semen collected
Vol.(ml.) Sperm No. x 10 8 Live (%)
No. I No.2 No 3 No.1 No.2 No.3 No. l No.2 No.3
Day-6
Ram A 0.7 1.4 0.8 39 45 45 90 92 88
Ram B 1.0 1.0 1.1 41 31 31 90 S6 88
Ram C 0.8 0.6 0.5 34 45 45 82 95 95
Ram D 0.7 1.0 0.4 54 43 36 95 95 95
Day-15
Ram A 0.6 1.0 0.8 40 40 35 90 90 90
Ram B 1.0 1.0 1.0 40 35 30 90 S5 90
Ram C 0.0 0.6 0.4 32 40 45 80 90 95
Ram D 0.7 0.5 0.7 45 40 35 95 95 90
7. 2. 2. 4 Semen Quality traits
Semen quality varies with frequency of ejaculales quality. Ejaculates to the extent of even
20 to 30 a day followed by successive collections of equal number of ejaculates the next day
have been obtained. Collections to the extent of 2 to 6 per day also have been
obtainedoveraperiod of aweekor 10 days (Chang, 1945). Salamon and Robinson (1962)
observed that season and nutrition did not measurably affect frequency of service nor there was
any apparent effect of season on volume, density or sperm count. However, marked effect was
seen on these characters due to high protein ration. Satisfactory fertility can be maintained even
with frequent ejaculations if the total number of spermatozoa is more than 80 x 10 6 . Fall in
lambing rate is observed when the sperm count is reduced.
i) Colour
The colour of ram semen is crearny. Variable grades are noticed according to frequency,
season, age, rest and among individuals.
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