Semen Tank 101

Having your own semen tank is becoming increasingly popular. However, managing your own tank can come with a lot of uncertainty and pressure. Producers can increase their breeding success by using proper handing techniques as well as tank management. This article will ease your mind and educate you about the basics of semen tanks and semen handling.

The Parts of a Semen Tank

Specific terminology is used when referring to the parts of the tank and the reproductive material inside. The main parts of a tank are the canister, the cane, the goblet, the cane tab, and the tank itself. You may hear reference to "straws" when talking about semen tanks; however, a straw is what houses the frozen reproductive material, such as semen or embryos, and is not specifically part of the tank.

The cane, goblet, and cane tab work together to hold the straws in place. A goblet is a plastic cylinder with an open top that directly houses the straws. The goblet is attached to the cane, which is the metal part that sticks down inside the tank. On top of the cane is the cane tab, which is what you see when you look inside the tank. It typically houses a label or other identification material.

The final parts are the canister and the semen tank itself. The canister is what the cane sits in when it is inside the tank. There is a handle at the top of the canister that can be held at the opening of the tank. This allows a technician to pull the canister up into the neck of the tank to look at the cane tabs. Tanks typically have more than one canister, with an average number of about six canisters.

Semen tanks consist of two tanks meshed to create a double-walled effect. The smaller tank inside houses the canisters as well as the liquid nitrogen – freezing agent, meanwhile the larger external tank serves as protection. Between the two tanks is a vacuum and some insulation; the vacuum is critical for nitrogen retention inside the neck of the tank. The lid is key to keeping out debris moisture, which can then affect the cork. The cork is there to allow the nitrogen vapor to escape safely, which is attributed to the tank's nitrogen needing to be replenished over time.

Semen Tank Management

Proper tank management is essential to protect the valuable reproductive material stored inside. The first thing to remember when managing a semen tank is to monitor the nitrogen levels. The level of nitrogen depends on the size of your tank, but a good rule of thumb is to keep the level around the top of the canisters. Some companies might offer a tank refill schedule; however, you must also personally monitor the nitrogen levels in your tank. Keeping a history of these levels can help to show if there are any problems or damage to the tank.

Keeping the outer shell of the tank in good condition will help to extend the lifetime of your semen tank. Protecting the bottom of the tank from rough surfaces such as concrete can help protect it from abrasion and moisture damage. Housing your tank on top of a wooden surface, such as a pallet, is a good way to avoid these issues. The tank may be cleaned with mild soap and water but ensure that the clean tank is dried. Getting water around or on the cork of the tank can cause it to freeze inside the neck of the tank.

Early detection of tank damage can help to ensure that the stored reproductive material is safe. Again, the primary way to do this is to record or check the nitrogen levels on tanks weekly or biweekly. These records will elucidate when or if the vacuum within starts to give up. The other way to identify a damaged tank is by visual accumulation of frost. Frosting around the lid or cork can show early signs that the vacuum is giving up. However, if the outer shell of the tank is covered in frost, it is a signal that there has been a complete loss of vacuum. This means you need to move the contents immediately to another tank, as all the nitrogen within the damaged tank will eventually be lost.

Handling reproductive materials

Proper handling is key in maintaining the quality of reproductive materials stored in semen tanks. Improper handling can quickly degrade the quality of semen and embryos. When semen and embryos are frozen, part of the process is plunging them into liquid nitrogen. After the semen is cooled to -130°C, it cannot be raised above that temperature without damage being done to the cell structure. This typically happens during handling before the time of AI, such as searching for straws or transferring canes. Using proper handling techniques can help to ensure that the quality of reproductive materials is safe.

When handing frozen materials, it is imperative that the canister or canes are held below the frost line. The frost line can be seen at the neck of the tank and is widely known as the area where the straws can be viewed. According to the paper written by Brad Stroud, DVM, the canister or cane can only be held in the neck for five to eight seconds. After eight seconds, severe damage can occur because of the extreme changes in temperature in the neck of the tank (see image).

Straws of both semen and embryos will be pulled out of the tank for thawing and use at some point. However, ensuring that this is done properly decreases the effect their removal has on the other straws. Using your fingers is convenient; however, the heat coming from your body increases the temperature around the other straws. Having tweezers or other similar equipment can help to decrease that damage. Make sure that 'breaking straws', also known as a locating straw, is done in the presence of a trained professional.

Having a proper log of all canes and straws within the tank can help with the location of reproductive material. This can decrease the need to move and pull canisters into the neck of the tank. The id or code that is used on the cane tab and the cane location should be logged so that technicians can quickly access the straw. Some canisters are labeled on the neck of the tank with numbers one through six and color-coded on the handle of the canister.

Conclusion

Overall, semen tanks are an essential part of many operations and are convenient to have on hand. Ensuring that everyone interacting with the tank is properly trained can protect the quality of the reproductive material. Small improvements in tank management and reproductive material handling can increase success in your program's reproductive endeavors.

References

Amundson, O., & Brandt, K. (2023, October 26). Proper Semen Handling Techniques. Retrieved from South Dakota State University Extension.

Quality Semen Tanks. (2015). Parts of a Semen Tank and How They Work. Retrieved from Quality Semen Tanks.

Parrish, J. (2018). Storage & Handling of Frozen Semen. Retrieved from The University of Wisconsin Madison.

Stroud, B. (2012, December 3). Consequences of Mishandling Frozen Semen and Embryos. Applied Reproductive Strategies in Beef Cattle, 191-203.

Thomas, J., Andersen, C., & VanWye, G. (2021, September). Care and Maintenance of a Liquid Nitrogen Tank. Retrieved from University of Missouri Extension.