Use of incorrect A.I. techniques can lower the overall success rate of the A.I. breeding program. At one time, most producers learned correct techniques in semen handling and insemination procedures, but, unfortunately, many have developed some bad habits. Reviewing proper procedures should help eliminate some of those common mistakes.
Maintenance of Semen Tank and A.I. Equipment
Keep semen tanks in a secure, clean, dry place away from corrosive chemicals. Your tank’s location should allow for easy moving for filling with liquid nitrogen. Store tanks in a visible place, and frequently monitor the nitrogen level. Only store about a 6-month supply of semen. Make sure your investment is insured and secure.
Always check the semen inventory list before removing semen from a tank to make sure each time that the correct canister is used. Do not lift semen above the frost line in the neck of the nitrogen tank. Dangerous temperatures exist in the upper half of the neck in the area beyond the frost line. Exposure will lower subsequent fertility.
Store insemination equipment in a clean plastic or stainless steel box. Keep this box closed when it is not being used. All equipment should be clean when returned to the box. Always maintain sterility of the plastic sheaths used to cover the straw gun.
Proper Semen Handling
Identify and restrain the cow or cows to be bred before thawing the semen. Be sure that cows being inseminated are in heat or at a proper interval after being synchronized. Use the AM-PM rule, or breed at a specific recommended time after hormone treatment.
Wear safety goggles for eye protection when handling semen. When preparing the A.I. gun, quickly remove the straw of semen from the goblet with tweezers and not fingertips. This helps to keep the straws in the goblet below the frost line and avoids warming the straw too quickly. It is generally recommended that only one straw be thawed at a time. If more than one straw is thawed, they should be agitated to prevent the possibility of freezing together during thawing. If synchronizing and breeding groups of animals, you can thaw several straws together as long as you are using them within 15 minutes.
Shake the straw after it is removed from the tank to eliminate any drops of nitrogen at the end of the cotton plug. This will eliminate the plug bursting off when it is put in the water bath. If you have a large group of animals to inseminate, have one person thawing and another breeding animals to use semen more promptly.
A 1-pint, wide-mouth thermos and a dial thermometer work well for thawing straws if you have a source of warm water. Thaw semen in 95°F water for 45 seconds. Electronic thaw devices are handy, especially DC versions that can be used with vehicles. Maintain accuracy by regularly checking temperatures and calibrating your thermometer.
After the straw is thawed, dry it off with a clean towel and check the printed information on the outside of a straw to verify the bull’s identity. Record the bull next to the cow’s number.
Maintain an accurate semen inventory. This can be easily done using PCDart or other dairy computer software programs.
Use semen within 15 minutes of thawing. Watch the time carefully, especially when thawing multiple straws. In cold weather, warm the gun by rubbing it with your hands. Place the end with the cotton plug in the gun. Cut the sealed end at a 90° angle about one-quarter inch from the lab seal. If the straw is not cut squarely, the plastic sheath may not seal tightly against the straw. Some semen will then back flow between the sheath and the straw rather than going inside the cow.
A half-cc straw contains about 10 drops of diluted semen, so each drop lost is 10 percent of the total contents and sperm numbers. A quarter-cc straw only has 5 drops. Every drop counts.
Place a sterile plastic sheath over the gun and seal it. Wrap the end in a paper towel to prevent exposure to the sun and to maintain sanitation. Sheath protectors can also be useful. Then place the end of the gun in your shirt or pants pocket to maintain temperature on the way to the cow. During hot weather, do not place the insemination gun in direct sunlight or on hot surfaces. This will kill sperm cells.
Correct Semen Placement
After the gun is loaded, clean the region of the vulva to prevent contamination of the vagina and uterus. If you are not completely sure the animal is in heat, pick up the cervix and uterus and see if you get a clear mucous discharge from the vulva. If the mucus is present, it is a good sign that she is in heat.
Insert the gun in the cow upward at a 30° angle. This avoids entering the bladder. Remember: Inseminating a cow does not require much force or pressure. Do not force the gun. Try to move the cervix around and bring it to the gun. Take your time, relax, and concentrate on technique. If the cervix is over the rim of the pelvis, pull it back toward you and guide the cervix to the gun. If the gun is getting caught in folds of the vagina, try stretching the cervix away from you to free the gun and allow easier passage to the cervix.
Deposit semen in the body of the uterus. This area is less than 1 inch long and is about the size of a dime. It is located immediately in front of the cervix. A common mistake is to deposit the semen several inches into the right uterine horn.
Feel the end of the gun with your finger when you are just outside the cervix. Be sure the gun is passing through the cervix and that you are not just stretching the vagina. When the tip of the insemination gun passes through the front ring of the cervix, it is in the uterine body. Check the location by placing your index finger in front of the cervix. You should just be able to feel the tip of the gun. After you feel the tip of the gun, lift your index finger and slowly deposit the semen over a 5-second period. Be sure that your fingers are not misdirecting the flow of semen or blocking a uterine horn. Reposition the gun each time the animal moves.
If the cervical mucus of a cow previously bred feels thick and sticky, the cow may be pregnant. On repeat services, it is best to deposit the semen just past the half-way point of the cervix. Be careful because you can inadvertently cause abortion.
Certain problems can occur. If you find blood on your glove, be gentle. Concentrate on placement. Practice proper sanitation procedures. Some cows are obviously more difficult to inseminate. Be patient and don’t give up on the hard ones. They too will work.
Researchers at the Pennsylvania State University developed techniques in radiography years ago to evaluate accuracy of insemination very clearly. These techniques overcome some of the limitations of the earlier dye techniques used to evaluate placement. A study was reported in which 20 professional technicians and 20 owner-inseminators were evaluated using the radiography technique. Each inseminated a total of 20 reproductive tracts. Radiographs were taken to access inseminating gun placement.
These data showed that only 39 percent of the gun tip placements were in the uterine body. A total of 25 percent of the gun tip placements were in the cervix. Twenty-three percent were in the right uterine horn, and 13 percent were in the left uterine horn. Sixty percent of the semen was distributed in the cervix or disproportionately in one uterine horn. Only 40 percent of the semen was located in the uterine body or equally distributed in both uterine horns.
The normal ratio of ovulation or release of eggs is approximately 40 percent from the left ovary and 60 percent from the right ovary. Because migration of embryos is rare, the pregnancy ratio should be the same, 40 percent left uterine horn and 60 percent right uterine horn. This is an easy way to have your veterinarian check on the job you are doing with correct semen placement. Data on 100 or more pregnancies are required for a proper evaluation.
The need for retraining may be necessary because many have not yet mastered the expertise required for proper gun tip placement and insemination. A goal of first service conception rates of 55 percent or more and fewer than 1.8 services per conception is reasonable for breeding virgin heifers. Goals for lactating cows might be at 40 percent conception and fewer than 2.5 services per conception. Set goals that are challenging but realistic compared to historical herd performance.
Practice good insemination techniques; consider retraining. You may improve your herd’s conception rate. Your cows can’t make up for your mistakes in improper semen handling and placement.
When Is the Correct Time to Breed?
It has been thought for some time that optimum conception is achieved if an animal is bred 14 hours after onset of heat. With proper heat detection, acceptable results can be obtained with the AM-PM rule.
Recent evidence shows that animals bred once a day in the morning will produce comparable results to the traditional AM-PM rule. This is especially useful when artificially breeding heifers that are generally not located near the milk parlor. Breeding once daily in the morning is preferred over breeding in the afternoon, usually because higher proportions of animals show first signs of estrus late in the afternoon or during the night.
Research from Virginia Tech shows that highest pregnancy rates occur when animals are bred 5 to 12 hours after the first signs of estrus, which is defined as the “red zone.” If you breed at 12-hour intervals (for example, 6 a.m. and 6 p.m.), you would be always hitting the red zone. If you breed once a day, you are only in the red zone half the time (even though once-a-day breeding has been shown to be effective).
If you breed twice daily but at intervals other than 12 hours, you must miss part of the red zone. For example, if you breed at 8 a.m. and 5 p.m., you are breeding at 8- and 16-hour intervals. Therefore, there are 4 hours each day when animals can come into heat and you will be out of the red zone. In this example, a cow coming into heat from 9 p.m. to midnight will be bred outside the red zone.
Producers trying to get an edge on optimum fertility need to make the most of their opportunities. If you consider 5 to 12 hours after the first signs of estrus as the red zone, or the most optimal window to breed, look to see how many times you breed during the correct period. Of course, accurate detection of early signs of estrus is critical to success.
Once-a-day artificial breeding done in the morning can be used effectively. Optimize heat detection and conception rate management techniques. This does not mean once-a-day heat detection. Heats must still be detected two to three times a day for more than 15 minutes per observation. Moving animals prior to observation helps. Animals are more active on dirt than concrete. Feeding and milking times are not the best times to watch animals for heat. Use prostaglandins to bring groups of animals in heat together and increase heat activity.
Before you give once-a-day breeding a try, look at your conception rate, average days to first service, and percent heats observed on DHIA, and make sure you do not need to improve in those areas first.
The following checklists are designed to help you self-evaluate your semen tank maintenance and semen handling insemination techniques. We hope you find this checklist helpful to review your semen handling procedures.