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 span.
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.