Semen collection in domestic animals
The collection of semen from domestic animals typically employs the
use of an artificial vagina (AV), electroejaculation (EE), or digital
manipulation.
Artificial vagina:
Each species requires its own type of AV; the basic construction,
preparation, and usage have many common traits. The temperature of
interior of AV is maintained by placing warm water between an interior
liner and outer casing. The inner liners are generally made of latex and
have a smooth to coarse texture depending on the species from which
the semen is to be collected and individuals male’s preference. The
outer casing can be either rigid or soft, water at appropriate temperature
is placed into the AV through a valve, then air is added to create the
proper level of pressure.
The AV is lubricated with sterile jelly to permit an intromission of the
penis into the AV. the collection end of the AV has a director cone to
which the semen collection vial is attached. Depending on ambient
conditions, the collection vial is frequently protected with an insulating
cover (jacket) to prevent temperature shock to the spermatozoa.
Electroejaculation(EE) :
There are different types of commercially available electroejaculators
with automatic and (or) manual controls and rectal probes designed for
individual species. The power supply to the control units may be
generated by either alternating(AC) or direct (DC) current sources.
Digital manipulation:
Digital manipulation is the procedure of choice for collection of semen
from the boar or dog and in general, involves imitation of the pressure
exerted by the female cervical or vaginal components on the penis.
Collection techniques
Bovine:
From a practical standpoint and based on predictability of response,
collection of semen from bulls is performed by the use of AV or EE. The
AV should be selected for proper length. It is necessary for the bull to
ejaculate while the tip of penis is within the directing cone for the
spermatozoa. The collection of semen with an AV from younger bulls
should be done with an AV made from a casing and liners which have
been shortened (1/2 to ⅔ of the length for mature bulls). The warm water
at a temperature of 42 to 46c° at the time of semen collection. The
ambient condition determines the temperature of the water used to fill
the AV.
The bull must be prepared by (teasing) before actual collection in order
to maximize ejaculate output. In addition, the bull is allowed to mount 1
to 3 times before the semen is collected. When the bull is firmly on the
mount steer, the penis is deviated as the bull thrusts.
During these initial thrusts made by the bull, no attempt is made to
collect the seminal fluids that is ejected.
Once the bull has eliminated seminal fluids during these false mounts,
the bull is then allowed to mount the steer, the penis is again deviated
and directed into the AV. the bull will lunge, complete intromission and
ejaculate within few seconds.
The AV is changed at each collection to prevent contamination of the
ejaculate by the bacteria, debris, and dead cells.
Equine:
semen is routinely obtained from the stallion with an AV. A mount mare,
or a mounting phantom to which the stallion is conditioned to mount,
is generally needed for the collection of semen with AV. The phantom is
a padded horizontal tube on which the stallion is trained. The mount
mare should be in estrus in order to provide a controllable animal.
The mare is prepared by clipping or wrapping the tail for sanitation and
to prevent penile abrasions during semen collection. This is followed by
thoroughly washing, rinsing, and drying the penile area.
After preparation, the mare is restrained, and after the mare is restrained
appropriately, the stallion is allowed to approach the mare from the rear
and slightly toward her left side.
After the stallion mounts, the collector deviates the penis toward the AV
by grasping the shaft of the penis rather than the sensitive glans.
As the stallion moves further onto the mare. The penis is guided into the
AV and the stallion will begin thrusting motions in order to complete
intromission At ejaculation, an up and down motion of the stallions tail
generally occurs, and ceases after ejaculation and the stallion begins to
dismount.
Ovine:
Semen is collected from rams by EE or with an AV, Depending on their
previous training. Rams can readily be taught to service an AV while
mounting a ewe. Electroejaculation is more commonly employed in
clinical practice because it is easier to obtain semen by EE from rams
untrained to ejaculate in an AV. To collect semen by EE, a threeelectrode rectal probe is inserted into the rectum of the ram and semen
is collected as in the bull.
To electroejaculation a ram, two different approaches may be
considered. One approach allows the ram to remain standing within a
crate with removable boards designed to limit forward and backward,
and lateral movements of ram.
A second method is the lateral recumbency approach. This allows easy
exteriorization of the penis but requires more physical restraint by
assistants.
Basically, the ram is cast so that he is sitting on his haunches with his
shoulder held between the standing holders knees. The operator gently
exteriorize the penis by retracting the prepuce. Once the tip of the penis
is exposed, it is grasped with a piece of gauze and the ram is then
moved to lateral recumbency. Next, the probe is inserted into rectum
and stimulation applied. The semen is collected into a warm container,
and rams generally electroejaculate using stimuli ranging from 0V to a
maximum 6V.
Canine:
Semen collection for the canine species most commonly involves DM of
the penis and less frequently the use of an AV. Collection of semen is
often facilitated by the presence of an estrus bitch. The female is
restrained to prevent movement in an area which provides secure
footing. The male is brought up to the female on a short leash and
allowed nasal-genital contact.
Initially, the penis may be massaged through the prepuce in order to
stimulate erection. After partial erection has commenced, the sheath is
gently retracted behind the bulbus glandis and the penis cleaned with a
cotton pledget saturated with warm water. Digital pressure is then
applied behind the bulbus glandis to complete erection. the male
frequently begins to ejaculate while the penis is being handled. Gentle
massage of the tip of the glans penis may elicit further erection leading
to ejaculation.
There are three fractions to ejaculate. The first fraction is clear and
nearly sperm-free, the second fraction is sperm-rich and the final
portion is watery and sperm-poor.the sperm-rich fraction can be
collected in a warm funnel attached to a sterile test tube.
Following ejaculation, the male should be checked periodically to be
sure that detumescence and retraction of the penis has taken place.