The handling of your semen inventory plays a critical role in its ability to impregnate your AI candidate. Most importantly you want to be sure that you handle it properly each and every time you open the lid to your nitrogen tank. When searching for a desired cane in your tank, the full cane should be kept well below the frost line in its neck. Search for the treasure with a flashlight, not with natural light. The desired straw of semen should be removed from its goblet, and the cane returned to below the frost line, in under three seconds. This strict time restraint is necessary to be confident that the viability of the other straws on the cane have not been compromised. Once removed, the straw should be shaken slightly to remove any liquid nitrogen that might be clinging to its interior or exterior surfaces. If this is not done, you risk the straw exploding when the nitrogen residue is submerged in the warm water. Transfer the selected straw immediately to a 95º F thaw unit in order to protect your semen’s viability. It should remain in the unit for at least 30 seconds to 40 seconds before being removed for use. Do not allow your water bath to drop below 92º F or go above 98º F. If you let your water bath get too cool, you are compromising sperm recovery. If you let it get too hot, you may “cook” the semen, also reducing the number of live cells available for work per insemination.
After properly thawing the semen, you have a maximum of 15 minutes to deposit the semen in your doe’s reproductive tract for an optimal conception rate. The longer the semen remains in the straw, the greater the loss of viability.
Viewing Thawed Semen
The purpose of viewing semen is to determine its viability (the number of dead cells as opposed to the number of live), the motility (how fast and well the semen moves), and the percentage of abnormalities (the volume of less than perfect cells). To make such determinations, some minor equipment will be needed i.e., a microscope, slides and micro cover slips. We recommend that all AI technicians own a microscope. Certainly the quality of the microscope should be adequate to facilitate the viewing of the semen, but does not need to be of the highest quality. However, the microscopes that can be purchased at toy stores and hobby shops, usually have very poor optics and make seeing the cells virtually impossible. You must be able to view the cells 100x their normal size to see them at all, 250x is much preferred. In addition, the task is performed more easily if the unit has its own light source and is not illumination created by mirrors. Look for a unit that plugs into the wall and utilizes a bulb for its light source. The microscope available through BIO-Genics, LTD, Item # M900 Compound Microscope, is very reasonably priced and more than adequate for this purpose. This unit has the ability to magnify your image up to 400x its normal size, and has its own light source. Convenience is the key to this process, or else you may find the unit sitting on the shelf collecting dust. The more convenient it is for you to view the semen, the more likely you are to be consistent about doing it
When thawing semen, it is important that we understand the difference between thawing semen for insemination purposes and thawing to view its viability. These thawing techniques differ considerably, and each technique will give you a very different picture.
For the purposes of successful insemination, we highly recommend the semen be thawed at no less than 92º F, and no greater than 95.2º F for a minimum of 30 seconds. This allows for an ever rising temperature, if a proper water bath is used in the thawing process. You should use either the first drop of the cut straw, or the last. You must keep in mind however that these are the poorest examples of what is contained within the straw. As a result, these lesser quality cells may appear considerably more sluggish than those more towards the interior of the straw. Some allowances should be made accordingly. As soon as possible following the removal of the straw from the thaw unit; or as quickly as possible following the insemination of the doe, the droplet should be placed on a microscope slide and then covered with a micro cover slip. Leave the droplet under the light of the microscope for a minimum of 2-3 full minutes. This gives the semen adequate time to “wake up” and begin to move more normally.
If you are viewing an entire .5cc straw (which is the recommended method for getting a more accurate determination of the cells true condition) it should be thawed at 100.5º F for a full 2-3 minutes then immediately viewed. This creates an environment more closely resembling that of the hosts normal body temperature of 101.5º F, giving us a better idea of the semen’s actual performance once at body temperature.
BIO-Genics, LTD’s method of processing is a slow, gradual one and is reflective in the response time of the sperm post-thaw. You will find that the longer the semen is warmed, the more virile its behavior. If you find the sample to be slow and sluggish, or non-responsive on initial exam, allow more warming time on the microscope table. The simple heat generated by the lamp will warm it enough that after a few moments you will find it to be more reactive.