Artificial Insemination With Fresh Chilled Semen...
Fresh chilled semen uses energy as it is cooled to 40'F (4'C) and
eventually re-warmed to body temperature. The life in-utero of
spermatozoa having experienced the chilling and subsequent warming
process is 24 to 72 hours, necessitating a more precise manner of
ovulation timing and breeding. When sperm is frozen for future use,
it is eventually stored at-322'F. (-180'C). This extreme temperature
preserves a sperm cell indefinitely but not without stress and
energy output. The thawed spermatozoa have a maximum life span of
twelve to 24 hours after insemination into the bitch. The
ultra-short life span makes success with frozen semen only possible
with precise mapping of the bitch's estrous cycle with definitive
detection of the LH release and the subsequent time of ovulation.
When a veterinarian receives a fresh chilled sample, the package
should immediately be opened. Attention should be paid to the
"impression of coolness". The ice packs should be at least cold, if
not still frozen. The package containing the semen should be removed
from the packaging material (usually newsprint). The tube should
contain the extended semen in a liquid state. Unfortunately,
occasional mishandling by the shipping company or by the shipper
placing the semen package in a non-pressurized compartment of the
airplane will cause the sample to arrive frozen. The freezing kills
the sperm cell and renders the sample useless.
One drop of the sample should be placed on a warmed microscope
slide. The rest of the sample should be refrigerated. Allowing the
chilled sample to warm to room temperature only allows the sperm
cells to speed up, using precious energy and shortening their life
As the drop warms on the slide, the accompanying paperwork with the
semen collector's evaluation of the semen quality, time of
collection and post-collection motility should be studied. The semen
drop is then analyzed and compared to the collector's evaluation.
In many cases, the semen will appear to be non-motile. However, as
the semen drop warms gradually side to side motility becomes noted.
The continued warming eventually shows the cells to have achieved a
normal forward progression. If no motility is noted after fifteen
minutes, the sample is most likely non-viable. If this occurs the
collector of the semen should be contacted to determine, if
possible, the cause of the semen's demise. In other cases where only
partial semen recovery is noted, the inseminator must use judgment
based on the connection of the semen, estimated total spermatozoa
numbers and the percent recovered. It may also be necessary to alter
the insemination method to that of an intra-uterine deposition of
the fresh chilled sperm to further remove sperm cell stress and to
aid its arrival at the fallopian tubes.
It is recommended that the refrigerated fresh chilled sample not be
warmed to room temperature or body temperature before insemination.
Having the sample in the uterus as it warms makes maximum use of the
conserved energy. All fresh chilled semen samples are handled in a
similar manner. However, many different commercial companies sell
packaging kits and extenders. One should always read their
instructions for any specific handling recommendations.