Consequences of Mishandling Frozen Semen and Embryos
Flawed cowboy logic in handling frozen semen and embryos can lead to problems before insemination even occurs.
by Kasey Brown, associate editor
STAUNTON, Va. (Oct. 15, 2013) — When an inseminator does everything right and there are still pregnancy failures, it is frustrating. This frustration led to more research in managing cells that have been frozen, said Brad Stroud, veterinary specialist with BioTech Productions. He spoke to more than 170 attendees of the 2013 Applied Reproductive Strategies in Beef Cattle (ARSBC) Symposium in Staunton, Va., Oct. 15-16.
Technicians and producers can damage sperm cells and reduce fertility while trying to select the right straw of semen out of a jug, said Brad Stroud, who presented a very entertaining look at flawed cowboy logic in handling semen and embryos.
A large issue is that no curriculum in animal science or veterinary programs includes frozen-cell management rather than simply how to freeze cells. He explained that when frozen cells are below -130° C, exposed to temperatures higher than -130° C, then re-exposed to temperatures below -130° C, the ice crystals rearrange. Often, these ice crystals form together into larger crystals, which invade very delicate cell membranes and cellular organelles.
Damaged membranes equate to enzyme leakage, which equates to fertilization failure.
Stroud noted that a standard 0.5-milliliter (mL) straw of frozen semen takes only 55 seconds in ambient air to dissolve all the ice crystals. For sperm motility to visibly decrease, it takes only 30 seconds in ambient air before being re-entered in the liquid nitrogen. In some conditions, it can take only 10-15 seconds of exposure to decrease fertilization.
“It can only take 10 seconds in the neck of a half-filled Dewar (semen tank) for the internal temperature of a frozen semen straw to reach -100° C,” he said.
A lot of common mistakes result from flawed cowboy logic. There are many opportunities where semen handling can cause damage — receiving a shipment, searching for samples to thaw, thawing samples, preparing a dry shipper, taking inventory, breaking a cane, Dewar-to-Dewar transfer, sale of semen at a cattle sale and improper storage conditions.
He suggested making a liquid nitrogen bath to use when handling straws of semen. It only requires towel clamps, forceps, hemostats, a liquid nitrogen bath (which can be made from cutting the top part off of a Styrofoam cooler) and eye protection. Taking inventory, splitting canes, reading straws and organizing straws into canes can be done in the liquid nitrogen bath with less likelihood of damaging the semen.
It is imperative to keep the internal temperature of straws below -130° C at all times, he emphasized.
Stroud offered a laundry list of tips for semen-tank maintenance:
- Keep Dewars at least three-quarters full.
- Keep an extra Dewar full of liquid nitrogen for topping off the main Dewar between scheduled fillings.
- The extra Dewar should be an exact replica of the main Dewar in case it needs to be used to replace the main tank.
- Use a nitrogen bath routinely for receiving and sending shipments and documenting the identification of sires.
- Consider the use of alarms that can warn you if something goes wrong with the tank.
- Always try to work below the frost line.
- Be disciplined in obeying the 8 second rule: Canes and canisters should not be exposed any longer than 8 seconds in the neck of the Dewar.
Stroud said one of the biggest obstacles to correcting semen-handling mistakes is educating people who don’t think they need educating.
He introduced an in-depth training DVD, which can be accessed at www.frozendvd.com.
Stroud spoke during Tuesday's ARSBC session focused on managing factors to improve pregnancy rates. Visit the Newsroom at www.appliedreprostrategies.com to listen to his presentation, view his PowerPoint slides and proceedings paper, and link to the training video.
Comprehensive coverage of the symposium is available online at www.appliedreprostrategies.com. Compiled by the Angus Journal editorial team, the site is made possible through sponsorship by the Beef Reproduction Task Force.
Editor's Note: This article was written under contract or by staff of the Angus Journal. To request reprint permission and guidelines, contact Shauna Rose Hermel, editor, at 816-383-5270.