The first and overriding principle of artificial insemination in swine is — if a sow is in standing heat, she can be bred; if she is not in standing heat, do not attempt to breed her.
This key to maximizing fertility rates in the breeding herd requires a solid understanding of AI basics, timing of insemination, use of lubricants, boar usage, overbreeding and nine key semen-handling principles.
For all of the years that AI has been practiced in the pork industry, we must always remind the inexperienced technicians of the standing heat principle. All other techniques and timing of insemination revolve around this core principle.
In sow farms served by our swine veterinary practice, I like to teach technicians to work with the basic nature of the animals.
With natural service, the timing is easier. The sow won't let the boar stay mounted if she is not in heat. The problem with natural service, however, is that we don't know the quality of each boar's semen.
If we could use the same concept in checking for standing heat that the boar would normally use, we would have a big advantage, because with AI we know the semen quality has been checked before a sow is inseminated.
In most cases, one insemination/day is adequate. Try to set up a schedule that ensures repeat inseminations will occur less than 24 hours apart.
For example, breed sows scheduled for a second service before the first-service sows each day. If doing a third-service mating, complete those before the second service, or 12 hours following the second mating.
During the insemination process, make sure the sow or gilt is properly stimulated, which means having a boar present. For all of the hands-free devices and labor-saving innovations, the presence of the boar is still needed to stimulate the uterus to draw the semen up into the uterine horns.
For the sperm, the uterus is a battlefield, so it's vital to help as many as possible to survive. They don't complete the journey on their own. They need a strong, powerful current pulling them up into the uterine horns. This cannot be accomplished well without good, face-to-face exposure of the boar with the sow.
Normally, I do not recommend the use of cleanup boars. However, I do recommend allowing every boar (vasectomized or intact) to breed a sow once a week. Allowing boars to breed regularly will make them much more useful and they will do a better job of stimulation.
Let boars breed cull sows or first-service matings. Keep a record for each boar to ensure they have this opportunity.
For twice-a-day services, make sure you allow six hours or more between inseminations. This includes weekend matings.
If this can't be done, practice once-a-day inseminations and make sure to keep the service interval under 24 hours.
With the rather hostile environment in the uterus, the immune system invades rapidly after insemination. It takes time for things to simmer down before the time is right to inseminate females with another dose of semen.
I've seen quite a few disasters with lubricants. Lubricants have no antibiotics, so contamination of the containers is common. Generally, a smaller package size for lubricants works best. Buying in bulk may save money, but the extra cost of using smaller packages is easily overcome with the reduced risk.
Remember, the lubricant travels all the way to the cervix just as the catheter does.
In addition, there are differences in the osmolarity or concentration of the solution, the pH or measure of acidity.
I like to use an AI lubricant that is backed by research, such as AiGel from ReproQuestLLC, located in Fitchburg, Wis. Contact the company by phone 877-270-1250, fax 608-270-1240 or email firstname.lastname@example.org for general information, or email email@example.com for sales information.
Nine semen-handling principles
Here are some guidelines for handling semen:
Ensure semen is fully cooled before packaging and before leaving the boar stud.
Ensure semen temperature is controlled during transport with cool (not frozen) gel packs or cooling units. Vehicle transport won't provide any effective cooling because the semen is bundled up and conductive cooling happens slowly.
Store semen in the cooling unit immediately after arrival at the farm. Do not let it sit out on the counter. It is surprising how often this happens. If you can't provide storage upon arrival, buy another cooling unit so the delivery person can store it directly when he/she arrives.
Track high/low temperatures daily. Rotate semen daily to resuspend the sperm.
Twice-a-week delivery should ensure that all semen is used within five days of collection. With delivery three times a week, semen should be used within four days of collection. And with daily delivery, semen should be used by Day 2. Check orders frequently to make sure this process is being followed.
Set the cooling unit at the same temperature the boar stud uses to cool semen (normally 61°F.). If you don't know what that temperature is — ask.
Check on-farm semen motility or activity using a microscope. I have seen many situations where the boar stud discovered a bad batch of semen, called the farm, and the farm had already used all of the semen. Remember, the boar studs check semen quality once a day. If you bred all of your sows before the boar stud conducted their tests, and found that a batch had gone bad, you're going to have to rebreed those females or you're in trouble.
Contact the boar stud on the proper procedure to check motility, because there is a huge difference among different semen extenders. One isn't necessarily better than another; they just affect the sperm differently. With Beltsville thawing solution (BTS) extender, for example, the sperm will be moving rapidly. With HEPES-based extenders, the sperm will not be moving rapidly. With TRIS-based extenders, you need to look at the sperm within 15 seconds before they stick to the glass slide and give the false impression that they are not moving. With HEPES-based extenders and BSA, the sperm look best after one minute.
Regardless of extender, the semen should be warmed for a couple of minutes prior to evaluation. An alternative is to use a slide warmer and allow the droplet to warm on the slide before putting the cover slip on and evaluating the sample.
Take semen to the barn in a cooler with gel packs from the cooling unit (not frozen packs). Only take what you'll use in an hour. Do not return doses to the cooling unit.
Make sure you are not using semen before the boar stud has provided polymerase chain reaction test results for porcine reproductive and respiratory syndrome. If this isn't possible, testing for PRRS virus by PCR loses most of its value. Normally, this means you'll be using semen starting the day after collection. There should be no loss in production with Day 1 semen vs. Day 0 semen. In fact, semen quality may be better because the extender has had time to stabilize the sperm and the antibiotics have had time to work.