Maximize A.I. Success with Proper Semen Handling
Published on Wed, 07/03/2019 - 4:16pm
Maximize A.I. Success with Proper Semen Handling
By Jaclyn Krwmowski
There’s absolutely no doubt about it, we’ve come a very long way in our bovine reproduction technologies. From the early research done in the early 1900s to the process becoming more mainstream in the 1940s, a lot of the A.I. success we see today is taken for granted. Countless research dollars, technology and experimentation has taught us what we does and does not work – and there’s still a long way for us to go! Sometimes it’s easy to forget in spite of all the technology involved, something as simple as the methods of semen care and handling contributes heavily to either a viable pregnancy or another open cow.
Proper handling is easily compromised on commercial operations when breeding multiple animals in a short amount of time. Having access to ideal facilities and equipment aren’t always possible for every situation, this makes it easy for proper procedures to get lost in transit. Whether you’re running several through the chute or using state-of-the-art facilities, the principles for handling frozen and live semen remain the same. Follow some of these basic tips and you can hope to increase the odds for better pregnancy rates.
About frozen sperm
Semen extenders provide excellent help to protect sperm cells in the process of being frozen and thawed. In the freezing process, intracellular water in the sperm cells is removed which prevents damage during crystallization. Once a frozen unit is thawed, however, this process cannot be repeated without substantial damage to the delicate sperm cells which, in turn, hinders or destroys their fertility.
For sperm cells to suffer a “thaw” doesn’t mean being left unattended at room temperatures or placed in a hot water bath. Studies show that an irreversible thaw begins as cold as -110F. (Note that a liquid nitrogen tank keeps frozen semen stable at -320F.) The degree of damage done depends on how much thaw has occurred for how long and the subsequent recrystallization process. But once the thaw has begun any refrozen sperm will have decreased fertility. The most common way this kind of damage occurs is when a straw or canister full of straws is held above the frost line in the neck of the tank for too long and then put back. Note this same process effects not only frozen semen, but also frozen embryos.
The safest environment in the world for thawed sperm is inside the uterus of a cow. Your job is to safely thaw the unit, keep it at a comfortable temperature, and deposit it inside a cow as quickly as possible. The general rule of thumb is to thaw in a warm water bath of 95F for 90 seconds. Some studies suggest this will give the best results for sperm recover as opposed to other methods. However, this method does carry a risk of cold shock post-thaw. If semen is mishandled in its delicate state after being thawed, the sperm can be significantly damaged if the temperature increases abruptly again. Once you’ve thawed a unit, you’re committed and need to keep the temperature as consistent as possible. This is why its recommended that the rod be warmed with the hands and carried close to the body or in a pocket as a sperm in transported. If water is kept at 95F, you can leave a unit in the water bath for some time, just be aware of its sensitivity to transition thereafter. Remember to also thoroughly dry each straw after thawing - even a small amount of water in contact with the sperm can be harmful.
Some sire companies recommend the ice bath thawing method or the pocket thaw method. For specific units that use specific semen extenders, these methods may be more beneficial than the warm water bath. Consult with your company representative for their specific recommendations.
Tank and semen handling
The nitrogen tank is an important tool in protecting your reproductive investments. Although they are bulky and made of metal, tanks are susceptible to even minor damage which can impair their ability to store nitrogen and protect your investment.
A typical tank in good condition can hold liquid nitrogen for six to eight months. Newer tanks tend to have better more reliable insulation and a stronger vacuum in the outer chamber than older ones. Older tanks may need to be checked more frequently to ensure they are holding nitrogen sufficiently. There are plenty of horror stories out there of tanks which went unmonitored only to be slow losing nitrogen and losing hundreds to thousands of dollars worth of units.
Tanks should never be set on top of concrete with no protection as the outer shell can erode resulting in vacuum loss. A rubber mat or wood palette is considered sufficient. When tanks are handled and transported, care must be taken to not apply abnormal stress to the neck or tube. Likewise, you want to protect the shell from even minimal damages. It’s a good practice to check the temperature of the tank whenever you are checking the liquid nitrogen levels.
How you handle and store your semen is one area you don’t want to compromise on. So much in A.I. success is beyond your control, but this is an exception. Train all those involved in the process to do things the correct way and avoid shortcuts. More successful pregnancies are certainly worth a little extra time and effort!