Make Artificial Insemination Work for You
By Callene Rapp | Oct 6, 2020
Photo by Adobe Stock/DelphPhotoStock
The invention of the microscope allowed researchers to discover sperm cells and their role in reproduction — a boon to farmers and ranchers. Artificial insemination (AI) took off in Russia in the early 20th century with the development of extenders that allowed a single dose of semen to be used on multiple females. In 1949, an English biologist whose expertise was in cryopreservation unlocked the secrets of long-term preservation and storage of semen.
Fast-forward to today, and all of these developments have made it relatively easy for homesteaders to direct the breeding program on their farms.
How AI Works
For AI to be successful, you need a sample of semen from a donor male. The methods and challenges of collection vary from species to species, but once a sample is collected, the same rule applies: Handle the sample carefully. Semen is susceptible to temperature shock, and must be preserved quickly once out of the male donor. Typically, an AI technician then evaluates the sample, calculates how many sperm cells are in the ejaculate, and decides how many doses of semen can be obtained (known as “semen extension”). Much depends on the quality of the fresh sample: Bull ejaculate can produce as few as 50 doses of semen, or as many as 500. Once extended, the semen is packaged into straws, and frozen in liquid nitrogen (LN2) for long-term storage.
Facilities that collect semen usually specialize in specific species, because of the differing requirements in handling live animals and their semen; some facilities collect cattle, sheep, and goats, while others specialize in swine.
Properly collected semen can be stored indefinitely in a collection facility, usually for a small monthly fee. These facilities maintain hundreds of thousands of samples in huge LN2 tanks, with backup systems and protocols to prevent loss.
Frozen semen straws are usually sold and shipped in batches of 5 to 10. These straws are held in “goblets” that typically hold five straws, and each goblet is clipped to an aluminum “cane” that holds two goblets. Even if you only have one cow to artificially inseminate, most companies won’t ship less than a full cane of semen — although some will ship a cane with only one goblet instead of two. The semen will be shipped directly to you, usually via a two-day service, in a well-padded shipping tank that’s much smaller than the semen storage tanks designed for farm use. Until recently, the shipping tanks used liquid nitrogen, but “dry shippers” have been developed that eliminate the need to transport liquid nitrogen. The shipping tank will be charged with enough vapor to give it a few days of life, so the semen must be used as soon as possible after it arrives, or transferred immediately to your regular farm tank. The shipping service will include instructions on picking up their tank a few days after delivery. Generally, you pay the breeder for the semen, and the storage facility for the shipping costs.
For fresh semen, such as for swine, an insulated styrofoam box with cold packs is used for shipping.
The author performs artificial insemination, using inexpensive but necessary specialized gear. Photos by Callene Rapp
Learning the Ropes
Artificial insemination isn’t a skill you can master by experimenting on your own through trial and error, especially in goats, sheep, and cattle. To be successful, you’ll need to enroll in a class and have a mentor.
Now that AI is fairly common, several facilities offer courses in the procedure. Many land grant universities also offer this training, sometimes as part of coursework, and sometimes as an extra class that’s open to the public. Your local extension agent can help you if no university classes are available.
The cost for such a class is usually several hundred dollars, but don’t be put off by the price. Good AI classes give you an opportunity to practice on many cows. In the classes I’ve attended, the only limit on practice has been how tired my arm became. Both courses offered an initial classroom session on a cow’s reproductive cycle, how to time AI, and various heat synchronization protocols. The courses also offered a look at a cow’s reproductive system laid out on a table, so I could study its appearance and then practice passing an AI rod through the tract. You should make the most of this, because you’ll have to do AI blind when you work on a live cow.
Most of the cows used in these classes are culls, brought in especially for the class. Practicing on good animals is a bad idea, as the potential exists to damage the cow’s reproductive tract by fishing around in unfamiliar territory with a stainless steel rod. The reason some of these cows have been culled is that their reproductive system is odd. If you can learn AI on these cows, working on your own animals will seem easy and simple by comparison.
As with any skill, you’ll need practice and repetition to become proficient at AI. If learning to artificially inseminate animals isn’t something you want to pursue, you have other options. The local large-animal vet may provide the service, or know someone who does.
Semen companies like ABS Global (formerly the American Breeders Service) have well-trained staff that provide the service to their customers. A local college or junior college with an agriculture program may also be a good resource. An instructor might have the skill, or know someone with training and experience. Don’t hesitate to ask around.
Weighing the Pros and Cons
Artificial insemination can be an incredibly useful tool, giving you access to sires that otherwise wouldn’t be available, and saving you the trouble and expense of keeping a male to breed just a few females. But AI has both upsides and downsides.
You’re limited to the sires that’ve been professionally collected. AI is most widespread in cattle, because cattle semen has been the most adaptable to freezing and thawing techniques; only recently has the technology evolved enough that AI in other species can approach similar success rates. Due to the species’ convoluted cervix structure, AI is generally more successful in goats when done laparoscopically, and this involves minor surgery to insert the semen directly into the body of the goat uterus.
Safety is also another factor to consider when debating the merits of AI or a herd sire. Males of any species can be territorial and aggressive, especially around females in heat, and intact breeding males have caused many injuries, even fatalities. When females are in heat, that male has one thought on his mind, and won’t let anything stop him from following through.
Another plus of AI is reduced disease transmission. Animals collected for semen sales are generally subjected to a variety of health screenings, and antibiotics are included in the semen dose.
The major downside of AI for most people is the initial cost of equipment, especially with cattle and using frozen semen. Liquid nitrogen storage tanks will cost several hundred dollars. LN2 must be purchased regularly, and the tank adequately maintained. But the equipment may still be more cost effective than feeding a bull who only breeds a few cows a year. You’ll also have to buy insemination rods, sleeves for the rod, and sleeves for the AI technician, as well as nonspermicidal lubricant for the service itself, but these are relatively inexpensive.
In swine, the semen is usually shipped fresh from the sire service, and the cost of the insemination pipettes is minimal. Since it’s fresh and there’s no nitrogen tank to maintain, your costs are basically limited to the semen and shipping.
Swine semen is shipped fresh, so you don’t have to maintain a farm liquid nitrogen tank. Photo by VenusVI
Probably the greatest challenge to successful AI, no matter the species, is timing the insemination to coincide with the female’s heat cycle. In some species, such as swine, heat detection can be difficult without a male around. And a male animal will typically breed a female multiple times, as many as she’ll let him, thereby depositing billions of sperm cells in her reproductive tract. He also learns rather quickly when she’s receptive and when she’s not.
Timing is more critical with AI’s single measured dose, and you’ll need to learn the proper timing for each species you intend to breed. In cattle, ovulation occurs at the end of the standing heat period (when a cow stands to be mounted), so the best time to inseminate is towards the end of that phase of the cycle. With swine, AI usually occurs after the female has been in standing heat for a bit.
Even for experienced breeders, the success rate of AI is never 100 percent, but education, timing, and patience will greatly increase your chances of success.
For the small breeder, AI offers huge benefits as well as challenges. Being able to make use of AI, especially when working with a heritage breed, can be the key to a successful breeding program. For many small breeders, the rewards are definitely worth the costs.
Callene and her husband own The Rare Hare Barn, a diversified family farm that raises Pineywoods cattle, Arapawa goats, Nankin bantams, and American Chinchilla and American breed rabbits.
Maintaining a Liquid Nitrogen Tank
Photo by Adobe Stock/Neznamov1984
Precautions are necessary when maintaining a liquid nitrogen tank for storing semen samples on your farm. Although liquid nitrogen (LN2) is a relatively inert element, it’s extremely cold — minus 320 degrees Fahrenheit. Contact with skin can cause severe burns, so be extremely cautious when handling LN2 and anything stored in it.
The exterior of an LN2 storage tank is typically durable aluminum. The tank has a narrow neck to help minimize evaporation, and is double walled to create an insulating vacuum. However, if the vacuum is lost, the tank won’t be able to maintain insulation. To prevent the scuffing that can create microscopic holes and cause a loss of vacuum, be sure to store the tank off the floor, on a mat or blanket.
LN2 vapors are nearly as cold as the liquid itself, so even if a tank is only half full, the temperature will still be adequate to preserve the contents. The length of time a tank will hold nitrogen is a factor of its size: Larger tanks with greater volume will maintain temperature longer. But any tank must be checked regularly, and refilled when the nitrogen level gets too low. Letting a tank run dry of LN2 will cost you its valuable AI contents.
You can test the LN2 level of the nitrogen in your tank with a specially made plastic stick that’s available from most semen supply companies. Insert the stick into the neck of the tank for a few seconds, and then withdraw it. Frost will collect immediately on the stick wherever it’s come into contact with the liquid nitrogen. Most tanks will maintain temperature while holding only a few centimeters of LN2 — but I personally get nervous when the liquid drops below half a tank. You should develop a habit of regularly checking your tank, and planning refills accordingly.
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