250
Artificial Insemination in Cattle
torch held by an assistant. (Several specula
are now available in which the light is incorpo-
rated in the instrument). Holding the insemi-
nating syringe in the right hand, the nozzle is
introduced a small distance into the cervical
canal and a quantity of 0.5 to 1 c.c. of semen
is deposited directly into the lumen of the
cervix. If the sperm is not required for other
cows, more than 1 c.c. may be used. The
syringe and speculum are withdrawn, and if the
cow strains, her back is pinched for a few
minutes.
There are various patterns of insemination
syringes and catheters, but whichever type is
used, it is essential that metal, which is delete-
rious to spermatozoa, shall not come into con-
tact with the semen. A useful, easily made
instrument can be constructed from a 20-inch
length of fine-bore glass tube. This should
have rounded ends to prevent any possibility of
damage to the cervix, etc. The glass tube is
attached to a 2 c.c. all-glass syringe by a short
length of rubber tubing (Fig. 1) or a rubber bulb
Pressure Tubing
2 c.c. All Glass Syringe
FIG. 1
may be used instead. When using the insemi-
nator shown in Fig. 1 the amount of semen
required for use in each cow, 0.5 to 1 c.c., is
taken up in the glass nozzle and no sperm
comes in contact with the 2 c.c. syringe. This
facilitates cleaning and sterilizing of insemi-
nator, as only the glass tubes need to be steri-
lized by heat and dried before use, and several
of these can be carried, a clean one being used
for each insemination. This type of insemi-
nator can also be used without a speculum.
The cervix is grasped by one hand per rectum
and the glass nozzle of the inseminator intro-
duced into the vagina, and thence through the
first or second ring of the cervix, where the
semen is deposited.
A 2 c.c. syringe is the most suitable, 5 c.c.
and 10 c.c. syringes being too heavy for use.
The pressure tubing should be pushed up over
the whole diameter of the 2 c.c. syringe, as
shown in Fig. 1, as this gives extra rigidity and
saves repeated breakages.
An alternative method of insemination has
been recently introduced in which the semen is
placed in gelatine capsules which have been
coated with paraffin wax. The capsules can be
inserted into the cervix by means of a capsule
"gun" designed for this purpose, or by hand.
When the hand is used, liquid paraffin should
be used for lubrication. This method is still
under investigation and it is not possible to
recommend it at present.
6. THE STORAGE AND TRANSPORT OF SEMEN
(a) For use within three hours. The precau-
tions to be taken are relatively simple. The
semen is transferred to a small, clean, dry test-
tube. In warm, summer weather, no special
temperature precautions are necessary.
In
cold, winter weather, the semen must be pro-
tected from a sudden fall in temperature; this
may be done by placing the test tube in a waist-
coat pocket or by wrapping it in cotton wool and
placing it under the dashboard of a motor car,
etc. At all times it should be protected from
bright light and must never be exposed to direct
sunlight.
(b) For use at an interval greater than three
hours. It has been established that cooling is
the best method of preserving semen. Sper-
matozoa normally live only a comparatively
short time at body temperature, and room tem-
perature (20° to 21° C) has likewise been found
too high for successful prolonged storage.
Most workers are agreed that the longest viabi-
lity of spermatozoa is secured at a storage
temperature of about 5° to 10° C. (40° to 50° F.).
In the cooling of semen for storage and its sub-
sequent warming for use, it is essential that the
change of temperature shall be gradual. or the
sperm will die from temperature shock.
The semen is transferred, using a Pasteur
pipette, from the collecting cup to a 5 c.c.
Pyrex storage tube. The tube is then filled
with liquid paraffin to exclude access of oxygen
to the semen. The tube is corked with a rubber
or freshly waxed cork stopper.
The tube is wrapped in cotton wool and
placed in a tightly stoppered, flat-bottomed con-
tainer tube, which is immersed for about 30
minutes in water gradually cooled to about
10° C. by adding ice. Finally, the tubes are
transferred to a refrigerator or to a thermos food
jar or flask containing shipped ice at 5° to 10° C.
(Fig. 2). Stored in this way, sperm of initially