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With proper handling of frozen semen and the breeding of cows and heifers at the right time, artificial insemination (AI) can achieve a fertilization rate similar to that of natural service.
“In one study, pregnancy rates from 13,942 first-service artificial inseminations were compared to 6,310 first services by natural service, and no difference was detected between AI and natural service,” says George Perry, South Dakota State University Extension beef reproductive management specialist.
Yet differences between technicians can cause wide swings in conception rates. One trial reported an average conception rate of 45% for a professional AI technician vs. 27% for a herdsman-inseminator.
The example serves to illustrate potential differences between technicians. Like professionals, producer-inseminators handling semen with care can have great success.
“Achieving a 60% to 70% conception rate on one AI service is an attainable goal,” says Jeff Lounsbery, a cattle producer and AI instructor from Centerville, South Dakota. “That’s comparable to natural service, since bulls typically get 60% to 75% of females to conceive on the first service.”
Optimum handling of semen requires attention to detail in four areas.
1. Extraction from the tank. “A detailed inventory of semen should be easily accessible, so that straws may be located and removed from the tank quickly to avoid exposing semen to ambient temperature,” says Perry. “When removing a straw from a liquid nitrogen tank, the technician should keep the canister, cane, and unused semen straws as low as possible in the neck of the tank.”
For this reason, Lounsbery likes to grasp straws with tweezers to extract them. This also prevents his fingers from touching and, thus, warming unused straws in the cane.
2. Water bath thaw. When placing straws in warm water to thaw, aim for a water temperature of 98˚F. Holding the temperature at that reading until removing the semen from the thaw unit is ideal. Forgiving range is 95˚F. to 98˚F.
“If only one or two cows are to be bred, you can use a thermos for thawing semen, but be sure to keep an eye on water temperature,” says Perry. “You can also use an electric thaw unit that has a heater, and it will hold the temperature at which it is set.”
With thermoses, a laminated thermometer or a dial-face water thermometer placed inside will monitor water temperature. Calibrate these annually to ensure accuracy.
“Assuming a water temperature of at least 95˚F., the straws should remain in the water bath at least 40 seconds and no longer than 15 minutes,” says Lounsbery.
Several straws can be thawed at once as long as these don’t touch in the water and stick together, decreasing sperm viability.
3. Inseminator’s gun. Maintaining the ideal temperature of the semen while loading the gun and transporting to the cow is critical. “In cold weather, warm up the gun and load it inside at room temperature,” says Lounsbery. “Outside, you can keep it warm by stuffing the gun down into your clothing.” Electric gun warmers can also be used.
Using sheath protectors helps protect the loaded gun from contaminants that could jeopardize the semen at the exposed tip or lead to uterine infection.
4. Insemination target. “After passing the gun all the way through the cervix, the ideal place for depositing semen within the reproductive tract is just beyond the last cervical ring at the very front end of the uterus,” says Lounsbery.
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