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The Art and Science of Artificial Insemination in Cattle
What is it?
Artificial Insemination or AI is, by definition, the deposition of sperm or spermatozoa in the female genitalia by artificial rather than by natural means, and a tool commonly used in breeding cattle. It is more common in dairy operations than beef, however beef producers are also known to use AI in their cows, particularly if 1) it is a small herd of cows or 2) it is a purebred herd. Dairy bulls are far more dangerous because of their increased masculinity due to the one-trait selection in females for milk production and lack of fear of humans due to being raised by humans and not by a cow. A bull that is raised by humans is a bull that sees humans as the ones to challenge for dominance, not other cattle, thus aggression towards humans is high, posing a much higher degree of danger towards the dairy farmer and the hands that work at the dairy farm in handling such a bull. This is why we see more use of artificial insemination in dairy production; no one wants to go and handle a very dangerous dairy bull every day to breed his cows. He's better off getting kicked by an ornery cow than mauled and trampled to death by a crazy, testosterone-hyped "pet" bull.
AI uses semen from bulls that are often a long distance away and too expensive to buy, overall, to breed only a few cows that are to be bred to this particular bull. Bulls that are used for AI are primarily proven sires, or bulls that have produced good calves from breeding with other cows. The semen was collected by the bull through an artificial vagina, as the bull, with penis protruding of course about to breed the standing cow, heifer or steer (yes steer, surprise surprise!), mounts and the person standing with the artificial vagina quickly steps in, slips the AV over the bull's penis, and lets the bull ejaculate into the AV. It is over in a matter of seconds, and with good timing, the semen is successfully collected and then quickly sorted, separated into individual straws (with glycerin added to increase ability to freeze quickly), then set in the canister of liquid nitrogen to freeze until it is time to take out a straw to breed a cow. Semen has to be frozen quickly to maintain viability. Slow freezing, like would happen in nature, will kill the sperm.
I realize you may be shocked to hear that steers are often used to collect semen from bulls. But you won't be shocked after I explain: Steers that have had an estrogen implant and have estrogen in their system (Estrogen is commonly used as a steroidal stimulant to improve marbling and meat quality in steers, believe it or not) are, to the bull, "females" in heat. Heifers and cows that go into estrus (heat period of the estrous cycle) have high levels of estrogen in their system, which can be "smelled" by the bull through pheromones excreted by the female in heat. A steer is used because it prevents accidental breeding by the bull, should a heifer or cow be used instead, if the person with the AV isn't fast enough to slip it over the penis, and instead the penis goes into the vagina of the heifer or cow being "bred". Not necessarily a good scenario.
The semen is frozen, and kept frozen often for a number of years before being put to use. Semen tubes are not frozen in your average-everyday freezer, though! It is stored in a canister that uses liquid nitrogen, which keeps the semen frozen at very, very low temperatures (down to -200°C or lower) to keep the sperm viable until it is unfroze for use. Semen that is frozen this way can be stored for a long time: some up to 30 years or more. Viable semen is semen that will be able to fertilize the ovum, or egg, in the cow. Semen with poor motility, irregular characteristics and are nonviable will not reach the ovum in the fallopian tube of the cow. Semen that has not been thawed or stored properly also will result in unsuccessful results.
How is it done?
AI uses several tools to deposit semen into the female bovine. However the first and most important tool is telling when that female has gone into heat. There are several ways this can be done:
1. Observation: This involves quite a bit of fence-sitting and sneaking around, and should be done for a few hours at a time in the early morning and/or late evening. Most cows display estrus behaviour in the morning hours and go out of estrus in the evening or at night. A cow or heifer in heat will display behaviour that isn't really normal to what you see her act as every other day. She will be bawling, pacing around the fence, attempting to ride other females or other females will be riding her. The rule of thumb that you should often go by is that the female that is being ridden is the one in heat, or "the one that stands is the one in heat." Also observe 1) rough hair on the tailhead; 2) mud marks on the side when the ground is wet; 3) nervousness; 4) frequent urination; 5) mucus on rump and tail; 6) a moist and swollen vulva. Dry cows (cows not lactation or producing milk) often show a noticeable swelling or enlargement of the udder during estrus, and cows that are lactating have a sharp decrease in milk production. A day or two following estrus, a bloody discharge is sometimes present.
2. Markers: Using the markers like some described above can be used, but other markers like pressure stickers can also be used. Markers are good for when you don't have time to sit on the fence and observe your girls in the morning; if a marker has been "broken" then it's a clear indication that that female has been ridden and is in heat. A chin-ball is also used on a gomer bull, which marks the females in heat with chalk or ink that is in the ball.
3. Gomer bull: A gomer bull is another word for a teaser bull that has been vasectomized, and is used to detect females in heat.
4. Use of Prostaglandin Follicle-Stimulating Hormone (PGF2-alpha): Uses of drugs that contain natural or artificial PGF2-alpha are used on heifers and cows for controlled breeding, and is a method that is used to get females to go into estrus simultaneously. It is a drug that promotes a morphological and functional regression of the corpus luteum, which in turn causes an increase in estrogen which makes a cow or heifer go into estrus. It often takes at least two or three injections of Estrumate or Lutalyse to get all the females to go into heat at the same time. Such hormone injections are also highly useful to treat silent or unobserved estrus if an owner hasn't seen a female go into heat, even though they know that she is not bred. In most cases, a heifer or cow will go back into estrus two to five days after being injected.
Once a female has been detected as in heat, she is put into the AI chute after 12 hours after estrus activity. This is because she ovulates during this time period, and is the opportune time to artificially deposit semen into her. Breeding her when she is in the midst of heat cycle will only produce poor results, i.e. not coming up as bred.
To breed her artificially, you must either have had previous experience and training in order to be successful at this, or hire an AI technician to breed her for you. Basically, the semen that has been frozen in nitrous oxide for a period of time is quickly thawed by placing a vial or straw in a container of water containing thawing ice (34-38°F or 0°C) immediately prior to use. The straw is then taken out, dried, then placed into the AI gun with the crimped end up. Be sure the gun is warm before use. Cut the crimped end with a straw cutter, the place AI sheath (or pipette) ove straw and AI gun, and lock the sheath on the AI gun. Protect the loaded AI gun from adverse temperature to prevent temperature shock. In cold weather, wrap the AI gun in a clean paper towel and place it inside your coveralls or coat to warm it up. Procede to the confined female, empty the rectum and clean the vulva. Then insert a glove, lubricated arm into the rectum and locate and grab the cervix. With your free hand (which ever hand you feel comfortable using), place the gun in the vagina and gently insert it forward. Negotiate through vaginal folds, and pass the AI gun through the cervix. Desposit the semen at the junction of the cervix and uterus. Then withdraw the gun and your arm out of the vagina and rectum. Dispose ot sheath, glove and straw after recording the breeding info from the straw (always important to keep record).
Advantages and Disadvantages
There is always good and bad things that go with every type of operation. Here are the following advantages of AI:
1. Increase use of superior sires
2. Semen dead sires can be used on your cows.
3. Controls diseases such as Trichomoniasis that can be transmitted through sexual contact from bull to cows
4. Makes it possible to overcome certain "physical handicaps" to mating, like mating animals of different sizes together (e.g, using semen from big mature bulls on small heifers)
5. Creates profits
6. Increase in pride of ownership especially of having calves or cows from outstanding sires in one's herd
7. Semen can be shipped to all parts of the world
8. Stored semen can last longer than a sire lives.
9. Lessens sire costs, especially when you have to look after bulls when a breeding season is over.
10. Used on small number of females; again, you don't have to look after a sire when he's already done his job on your herd of 5 or 10 cows.
11. Owner can order semen of a selected sire at any time
Now here are the disadvantages to AI'ing cattle:
1. Poorer conception rates than natural breeding; there is often a 60 to 70% chance that the females will "catch" after being bred artificially. Those that don't have to be rebred again.
2. Must conform to physiological principles. You can't breed a cow at any time; you have to know when she's in heat, how long to wait until to breed her, and breed her at the correct time.
3. Requires skill to get the job done. You may have to hire a AI tech to do it for you, or take an AI course to learn how to properly AI your animals. Experience counts in this art of breeding cattle.
4. It necessitates considerable capital to initiate and operate an artificial insemination orgainzation. You need facilities, equipment, and money to be able to operate as an AI tech.
5. Mistakes happen, especially if you choose a poor sire instead of a good one. Poor sires produce poor calves, and often poor sires are those that are unproven or virgin bulls.