Handling Frozen Semen and Preparing for Artificial Insemination

Artificial insemination (AI) has contributed enormously to the genetic improvement of the dairy cattle industry in the last 50 years. Frozen semen in 0.5 ml or 0.25 ml straws has become the universally accepted unit of storage and transfer of bovine genetics to cattle producers. While all the care is taken by the semen producers to collect the best quality semen and ship the same in the best possible way, there are times when results are not seen as required. One of the possible reasons is errors in handling of frozen semen.

Proper semen handling procedures from locating the semen in the liquid nitrogen tank to entering the cow's reproductive tract need review periodically.

Everyone should establish a routine for handling frozen and thawed semen that does not injure sperm cells and lower conception rates. Usually, errors made in the handling of frozen - thawed semen and the equipment used for artificial insemination are small. But the mistakes in semen handling frequently add up meaning their effects on semen quality will be magnified many fold.

Few things must be taken into consideration as farmers/inseminators get ready to thaw the semen and inseminate the cows/heifers.

Coordinate rapid transfer of semen between tanks. Involve two people and arrange tanks side by side. If possible fill the tanks with nitrogen before transfer. Raise canisters only to a level necessary to locate the rack of semen to be transferred.

Develop a semen inventory system and mount it on the wall above the tank.

Try to keep semen from one bull on each rack. Such systems help avoid unnecessary searching and exposure of semen to dangerously high temperatures within the neck region.

When preparing to thaw semen raise the canister into the lower portion of the neck where the specific rack of semen can be grasped. Lower the canister further into the neck. Secure the rack as low as possible in the neck, thus protecting the other straws from thermal damage. If straws cannot be easily removed from the plastic goblet, bend the top tab of the rack to a 45° angle. This reduces the chance of bending the straw.

Use tweezers to transfer the straw to the thaw bath. Quickly lower the rack of semen and canister into the body of the tank.

Thawing of the semen within the straw starts to take place at room temperature after only four seconds, and as a "rapid thaw" is critical to obtaining minimum damage to the sperm during the thawing process, damage will occur if the thaw takes place at room temperature. 

Few steps that are important for handling frozen semen include:

Keep insemination equipment clean, dry and ready at all times. The necessary equipment includes Thaw Unit, Thermometer, Lube, Gloves, Insemination gun, Paper towels, Cito cutter or scissors, Sheaths and Tweezers

The Thaw unit is one of the main equipments required to get the semen ready for AI. Either an electric thaw unit or a good reliable thermos is necessary to thaw semen. The goal is to maintain constant water temperature.

Occasionally check the accuracy of the thermometer.

Transfer straw immediately to thaw unit. The temperature of water should be 95-98 degrees F or 35-37 degrees C. Thaw straw for at least 40 seconds but not for more than 15 minutes.

Do not attempt to thaw semen at temperatures greater than 98 degrees F (37 degrees C). Thaw units of semen individually or max 3 straws as thawing more straws does compromise fertility.

With tweezers, remove the straw from thaw unit and dry the straw, using a clean paper towel. Place the straw in the fold of the towel to dry. A small drop of water can be lethal to sperm.

(It is assumed that the bull identification code has been checked prior to thawing and a proper semen has been taken out of the canister)

Shake the air bubble from the middle of the straw to the crimped end. Cut off the crimped end of the straw with a scissors or Cito cutter. Cut the tip of the straw squarely, through the air space below the crimp to achieve a 90 degrees cut. An angle cut may prevent the straw from fitting securely into the sheath. Check to see that the straw is firmly seated into the plastic adaptor or tip of the sheath depending on the type of inseminating device/AI gun that is used.

When assembly of the insemination rod is complete, gently depress the syringe to remove the air space at the upper end of the straw. Eliminate the chance of cold shock by warming the inseminating rod and sheath to body temperature (do not use water for this purpose). Use a paper towel and warm by use of friction. Must be done prior to the start of thaw process.

1.   Handle the thawed semen and prepare the insemination rod in a warm environment. Wrap the assembled insemination rod in a clean, dry paper towel and tuck it within your clothing for transport to the cow. Inseminate the cow within a few minutes after the semen has been thawed. Never take shortcuts when handling semen or inseminating a cow. Pay attention to detail. Never experiment on your own.

Five most common errors people commit when handling frozen semen and getting ready to inseminate the cow.

1. Raising the canister containing the semen canes above the frost line of the tank (frost line is usually 4 to 5 inches from the top) and removing the semen from the cane using fingers not tweezers. Exposing frozen semen to elevated temperatures in the neck tube of the tank has the potential to cause sperm damage.

2. Improper thaw bath temperature. Either not using a thermometer to obtain thaw bath temperature of 95 deg F/37 deg C or using a thermometer that needs adjustment, thus not obtaining the desired water bath temperature.

3. Not timing thawing. Frozen semen should be in 95 deg F water bath for a minimum of 40 seconds for proper thawing.

4. Straw not dried completely prior to placement in the insemination rod.

5. Straw not cut at proper distance from crimp sealed end (middle of air bubble) at a right angle straight across the straw to prevent semen feedback inside the sheath and insemination rod.

If semen is not thawed properly to begin with, the technician doesn’t need to worry about cold shock as “Dead sperms do not get cold shock”..!!!

Other considerations to get the best results
1. Handle animals gently to avoid unnecessary excitement before, during, and after breeding. Undue excitement may adversely affect sperm transport within the female reproductive system causing a lower conception rate.
2. Breed animals based on standing heat, remembering to breed the animals 10 to 12 hours after the beginning of standing behavior.

Amit Sachdev
India Consultant
World Wide Sires, USA
Email: indiawws@gmail.com