Many people are nervous about artificially inseminating their cattle.
But knowing a few of the basics about a cow’s reproductive system can help get you on the way to creating an artificial insemination program, said Colin Palmer, associate professor at the Western College of Veterinary Medicine at the University of Saskatchewan.
“The ultimate goal is to put semen at the right place and the right time. There’s nothing more complicated than that,” Palmer said during a recent webinar hosted by the Beef Cattle Research Council.
Many people have technical problems involving liquid nitrogen tanks or other equipment for thawing semen. It also takes a lot of practice to learn how to put the semen through the cervix into the uterine body.
“Lots of people are daunted by that and take AI courses to try and figure out what is going on,” he said.
Start with cows rather than heifers, and accept it will take a bit of practice before becoming good at inseminating, he said, adding the alternative is to hire an insemination technician.
Cows only display estrus for a short time during their heat cycles. Heat cycles average about 21 days, and estrus only lasts between 12 and 18 hours (although it can be as brief as two hours or as much as 50 hours).
“The only true sign that a cow is in estrus or heat is that she stands to be mounted,” said Palmer.
Many animals won’t even show this, or only display this sign for a short period of time. Secondary signs of estrus include chin resting, mounting other animals, bellowing, restlessness or clear mucous discharge coming from the vulva.
“If you see a red mucous discharge coming from the vulva, it is too late, and you have missed the ovulation window by at least a day,” said Palmer. “We need to get that semen into the uterus at least four to six hours before ovulation.”
In order to detect heat, you should observe your cattle at least twice daily at 12-hour intervals for about 20 to 30 minutes. It’s best to observe the cattle in a paddock where they have good footing. On windy, cold or rainy days, cattle will huddle up under trees to get out of the wind, and may not be inclined to show the symptoms of estrus.
Another way to tell if cattle are in heat is to keep records. Cows come into heat about every three weeks.
“Write it down if you think there’s some behaviour, and if you see the same behaviour about three weeks after, that’s a pretty good assurance that that’s the type of heat she displays,” he said.
Estrus detection aids or teaser bulls that have been surgically altered can also be a good way to detect estrus.
“No matter how you’re doing it, heat detection is a time-consuming activity,” he said. “We learned in all our studies that 10 to 15 per cent of cattle don’t display any behaviour that is obvious to the human eye.”
Variability in the heat cycle is based on follicular waves. Follicles develop on the ovaries. The eggs are inside these follicles, and they will eventually be released and ultimately, fertilized. A large percentage of cattle have either two or three waves of follicular development. Cows with two waves of follicular development will ovulate during the second wave, while cows with three waves of follicular development ovulate during the third.
“With our programs, we are able to not only focus on the second and third wave, but we can focus in on some of these other waves through the use of hormones that we employ,” said Palmer.
Two-wave cows have heat cycles that are about 18 to 20 days, while cows that have three follicular waves have a 20- to 23-day heat cycle.
“It isn’t really important whether they are two- or three-wavers. It’s important to understand that there are follicles that we are trying to focus in on and the reason for this estrus cycle length,” said Palmer.
Ovulation occurs about 22 to 27 hours after the onset of heat.
“You can inseminate her in that time, but she ovulates after she goes into heat,” said Palmer. “Because the length of heat is variable, it is good to measure the time of ovulation from the onset of heat rather than after she goes out of heat.
“If you were to be able to breed a cow when you really should, to optimize pregnancy rates, it would be in the latter half of when she is in standing heat.”
This gives the sperm time to get into the uterus, and move through the fallopian tubes to the egg. If the semen is deposited too far in advance before ovulation, the semen won’t be viable. Semen from natural-service sires will survive longer in the reproductive tract than semen that has been frozen and thawed. Semen doses can be as low as $10 and up to $100 a dose for purebred animals.
Artificial insemination should be timed for mid-estrus.
“The old rule used to be if you saw a female in heat in the morning, you should breed her in the afternoon around 5. If you saw her in heat in the evening, you should breed her the next day.”
Palmer recommends that producers talk to their veterinarian or an artificial inseminator to pick an insemination program.
Vaccinations should be completed at least two weeks before insemination. Producers need to have adequate facilities, including good cow-handling chutes and adequate labour to handle the insemination process.
“AI is time sensitive, and you have to have adequate help to move them through the chute,” he said.
Cows should also have good nutrition, and a good bedding area.
“Wet, sloppy, dirty areas can be stressful for animals. Stress on them can influence ovulation rates.”
Once the insemination program has been determined, all protocols should be written down.
Cows that are all inseminated in one day will not all calve in one day, but over a 14-day period.
“There will be a peak, and you need to be able to handle a large number of calves over a short period of time, particularly if you are cold-weather calving,” he said.