Getting cows pregnant as soon as possible after the voluntary waiting period is an important goal for your farm, and proper semen handling is a major part of improving pregnancy rates.
Semen quality starts with your nitrogen tank, which should be checked twice a month to be sure the nitrogen level is not changing drastically and not falling below 2 inches.
Tanks need to be stored in a dry, dust-free environment away from direct sunlight and elevated off the floor. When tanks are stored on concrete floors, they often corrode and will start to leak.
Keeping semen-handling equipment clean comes next. Dirty equipment needs to be disinfected with 70% isopropyl alcohol. Do not disinfect equipment with soap, because its residue is lethal to semen.
Care needs to be taken when retrieving semen from the tank to keep canisters below the frost line.
Raise them into the frost line for less than 10 seconds in order to find the unit you need. If you don’t find it in that time, lower the canister back into the bottom of the tank for 10 seconds.
Temperatures above the frost line can reach +54 F compared to -320 F in the tank or around -148 F in the frost line.
When removing the straw, be sure to shake it so that all the nitrogen droplets fall off, or the straw may jump out of your thawing cup.
Straws should be thawed in a warm water bath between 90 F and 95 F for a minimum of 45 seconds. Multiple straws can be thawed at the same time, as long as they are not touching each other in the water bath. When straws touch and freeze together, semen motility is reduced.
The number of straws thawed at once should not exceed the number of cows you can breed in a maximum of 15 minutes.
A study from Hawaii found that in warm conditions after the AI gun is loaded, you have about 6 minutes to breed cows before conception rates start to decline.
When you pull the straw out of the warm water, it needs to be dried well with a clean paper towel. Water is extremely lethal to semen.
Before putting the straw in the AI gun, it needs to be warmed up to 95 degrees by rubbing the gun in a clean paper towel, but be careful to not get the gun too hot. You can also warm it up against your body, by putting the gun in a glove, then between your skin and shirt.
When you cut the crimp off of the straw, be sure to cut it at a 90 degree angle so that it seals tightly into the sheath. Sheaths with inserts seal better and prevent semen from seeping back around the straw during deposition.
Sheath covers should also be used; they have been shown to significantly increase pregnancies per service.
Once you have the semen out and loaded, now is the time to make sure you finish strong with proper semen placement.
There have been many opinions about semen placement in the uterine body versus the uterine horns to place the semen closer to the site of fertilization.
Research has shown that neither placement method helps keep more semen in the reproductive tract; more than 60% will be lost in the first 12 hours.
What does make a difference is when the semen is deposited in the cervix instead of the uterine body. A study by Penn State of 800 breedings found that only 40% of the time semen was placed in the uterine body or equally in each horn.
The other 60% of the time semen was in the cervix or unequally distributed between horns. Twenty-five percent of the time the semen was in the cervix.
Before breeding, be sure to clean the vulva well to prevent contamination of the uterus.
Insert the AI gun at a 30º upward angle to avoid the bladder, using caution throughout the entire process not to force the gun.
First, stretch the vagina so that the gun doesn’t get caught in any folds. Then, keeping the gun still, gently bring the cervix over the gun.
Relax and be gentle. Some animals are not as easy to breed, but rushing will result in an open animal.
Once the gun is through the cervix and into the uterine body, you should feel the tip of it with your finger. This area is about the size of a dime. Using caution not to move the gun back into the cervix or into a uterine horn, deposit the semen over five seconds.
Close attention to proper semen care and insemination will improve your conception rates.
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