This article was initially posted on the “Shorthorn Select Genetics” website and has been reprinted here with permission by it’s author: Joseph A. Schallberger, DVM, PhD
Historically artificial insemination (AI) of cattle really began to be significantly employed by farmers in the 1950’s as both breeding cooperatives and private companies developed successful and profitable methods of preserving bull semen. Convincing skeptical cattle owners as to the value of AI and developing the infrastructure to get the semen into the cow so she became pregnant quickly evolved. The author is aware of semen frozen back as far as 1950 that exists and is viable. Properly frozen, and constantly maintained in liquid nitrogen tanks, bull semen may not have an expiration date.
Preservation of bull semen has been done by a variety of methods over the years. Each method had both its idiosyncrasies and its advantages. In chronological order the use of Ampules, “Magic Wands”, and Straws were the primary types of storage containers employed in the preservation of bull semen.
Homemade amp holder: small block of wood with appropriate size hole drilled in it.
Ampules were the primary frozen preservation reservoir for bull semen from 1950 to the late 1970’s when straws replaced them. Some bulls born in the 1970’s may have semen preserved in both ampules and straws. Most ampules contained 0.75 ml-1.0 ml of semen but American Breeders Service started using 0.5 ml ampules because 8 could be stored on a cane instead of 6. This resulted in an increase in the storage capacity of semen tanks. The number of sperm in most ampules exceeded 30 million which far eclipses the number in modern straws which may contain only 5 million. The excess semen in old ampules facilitates the splitting of amps to breed more than one cow. Ampules were frozen at a 45 degree angle so that when they were ready to be thawed it was easy to tell if they had been previously thawed (ie. horizontally level) which would make them worthless. It should also be noted that semen from different bulls stored in amps may have different colors (green, yellow, white, etc) as a result of the use of different semen extenders. The color differences in no way reflect on the quality of the semen.
Originally ampules were thawed in ice water baths. Four to six minutes for 0.5 ml amps and 10-12 minutes for 1.0 ml amps. Research has shown that they can be thawed in modern warm water (95 degree) baths for 2 minutes with comparable breeding success. A note of caution in that ampules being thawed can occasionally explode which can result in injury if one is not careful. It is a rare occurrence but it does happen. Most ampules after 1970 had a dot (red or yellow) on their stem that indicated the side which the user should apply pressure to “pop the top”. They were pre-scribed. Holding the amp with a paper towel minimizes shattering risks. For amps that do not have a dot (prescribed) a scribing device or a quality diamond/knife edged file can be used to scribe them so that the top can be removed/broken off. Specifically designed pipettes, to which a rubber squeeze ball could be attached for suction, were used to withdraw semen from the ampule. The pipette was then used to breed the cow. Pipettes are still available through different bovine reproductive supply houses to use with amps. The bulb can be replaced by a syringe and straw connector using the syringe to expel the semen in the cow. A simpler method is to purchase conventional sterile breeding straws (0.25 ml or 0.5 ml) and use a syringe (3.0 ml) attached to it to draw the semen from the amp into the straw. Syringe straw connectors are available through Reproduction Resources (www.reproductionresources.com). This method can also be used to split ampules to breed more than one cow. When the semen is drawn up to the plug in the straw this provides a seal so that the semen does not drain out. It is also important to remember to cut the end of the straw just as you would with a commercial breeding straw or it will not properly fit in the sheath because it is too long. Done properly, with the required number of cows available, one ampule can be used to breed 2-4 cows successfully, in rapid sequence.
Some old bulls had their semen preserved in “Magic Wands”. This method was originally developed by Dr. W. H. Dreher who managed Badger Breeders Cooperative in Shawano, Wisconsin. The Magic Wand was essentially a frozen breeding pipette that contained 1.0 ml of semen. Conception rates were generally higher (5-10%) but the increased space needed to store them in semen tanks hastened their demise. They were replaced by the “new” straws which took up less storage space in semen tanks. The Magic Wands were thawed at room temperature (3-4 minutes) and one end was nipped off with a toe nail clipper for the semen to be delivered. Connectors were used to extend the length of the Magic Wand for breeding the cow. Connectors available from the aforementioned Reproduction Resources can be used to attach a 3.0 ml syringe to deliver the semen through the pipette. Refer to the different figures to view the proper usage. Alternatively, by using a sterile warmed test tube the semen from a Magic Wand can be placed in it to then be split like amps. Using sterile straws and then a conventional breeding gun facilitates this method.
It is wise to check old semen for viability when using a bull for the first time. How the semen was handled and stored over the years can have a tremendous impact on its viability. All that is needed for semen to be evaluated by a qualified person is a small drop examined under a microscope for semen motility. A semen sample examination is well worth doing because it may prevent a breeding disaster. There is no quality check comparable to the 45 degree tilt in amps that can be used in Magic Wands or straws to confirm that it’s never been thawed and then refrozen.
Given that old bull semen is a precious commodity, and using it properly is important to breeding success, thoughtful planning is imperative in its usage. Understanding the nuances that are part of using old bull semen can easily make the difference between breeding success and breeding failure. Seeing live calves from quality bulls from 50 years ago that can be used to diversify and perpetuate quality cattle genetics can be very rewarding both personally and financially. started to become the dominate method of storing bull semen in the mid-1970’s because of ease of storage and simplicity of use. Semen concentration in straws was less than amps but the thawing process for straws was less damaging to the sperm so conception rates were generally comparable. The original straws contained 0.5 ml versus most straws today are only 0.25 ml in volume. The utilization of older straws is similar to what is done today with no additional necessary steps.
The methodology detailed below in this article has been used successfully by the author for many years. There certainly are other methods for using old bull semen stored in ampules or Magic Wands that may work equally well but each method can have its own idiosyncrasies as a word of caution. Producing a live calf is the ultimate measure of success.
Using Ampules
Thaw in warm water bath for approximately 2 minutes or in an ice water bath for 4-12 minutes depending on the size of the amp.
Remove the top of the ampule carefully using pressure on the pre-scored side or a scribe/file to score the the narrow neck before carefully snapping off the top.
Use a breeding pipette with a syringe attached to draw up the semen or transfer the semen to a regular straw using a syringe attached to a sterile straw.
With a breeding pipette breed the cow in a normal fashion. If a straw is used then a conventional breeding gun can be used. If the amp is 1.0 ml, and only one cow is being bred then a second straw can be filled and used to breed the cow a second time to maximize the chances of conception.
Using Magic Wands
Use a dog or cat toe nail clipper to cut off a 1/4” of the sealed end of the Wand.
Keep Magic Wand level to prevent any semen leakage.
Attach coupled end of the extender tightly to the cut end of the Wand.
Thaw semen semen for 3-4 minutes at room temperature.
Before semen completely thaws attach an air-filled syringe to the rubber tube connector to the Magic Wand.
Put slight negative pressure on the connector with the air filled syringe to hold semen in the the Wand.
Insert Wand and extender into the cow for breeding. Semen should be deposited slowly over 5-8 seconds by pushing on the syringe plunger.