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Dairy breeding tool becoming popular in beefDairy breeding tool becoming popular in beef

Producers can use sexed semen strategically to create replacement heifers, researcher says.

5 Min Read
A cow and calf in Montana.USDA ARS

Sexed semen has been available for a couple of decades in the dairy industry but now increasingly used in beef cattle.  Producers can selectively breed cows to a desired bull and choose the sex of the offspring.  This is beneficial if they want replacement heifers from their best cows, or bull calves from certain matings.

Dr. David Bohnert, Director and Professor, Eastern Oregon Agricultural Research Center, Burns & Union Stations, Oregon State University says the challenge with sexed semen in the beef industry is that we don’t use AI as much.  This is partly just logistics; it is difficult on large extensive operations to get the cows in for a week to get synchronized and bred or check for estrus.  A person has to be really committed to doing AI, he says.

“Another challenge with sexed semen is that conception rates are generally 10 to 20% less than when using regular semen.  Yet the use of sexed semen this may still be worthwhile in getting more calves of the desired gender,” he explains.

A producer contemplating use of sexed semen should look at the numbers—cost of semen, reduced conception rates and the value of the offspring—to see what if it might be worth doing.  “There are some advantages for the dairy industry where producers want heifer calves from their best cows.  They use the best dairy semen (for female calves) for cows they want to keep replacements from and beef semen (for male calves) on cows they don’t want replacements from, to get higher-value offspring,” says Bohnert.

“We did some studies here on use of sexed semen, and one of the things we found was that there can be a difference in conception rates depending on the protocol.  Here at Burns we used fixed-time AI and bred one group of cows with conventional semen and another group with sexed semen.  We had 20% lower pregnancy rate in the cows bred with sexed semen compared with those bred with conventional semen.  In our sister station at Union we did heat detection prior to the AI, and in that situation the sexed semen pregnancy rates were a little higher,” he says. Pregnancy rates seem to be a little better if the cow has shown estrus and is bred at the optimum time.

Strategic use

How you use sexed semen may also vary depending on how you market the calves.  Most producers won’t want to use sexed semen on the whole herd.  “You might use sexed semen on your best cows to produce heifer calves as replacements, selecting a good maternal bull as the sire.  For the rest of the cows you could use either a terminal sire for AI with sexed semen to produce male calves or just use a good terminal sire to turn out with those cows, figuring to sell all the offspring.  This could minimize your AI costs, just using sexed semen on a select group of cows to have superior replacement heifers.  You wouldn’t have to breed very many cows AI, knowing you will get heifers from almost all the ones you do breed,” says Bohnert.  This would provide all the replacement heifers you’d need.

Your best cows are often the best source of replacements, with genetics you’ve worked toward, and adapted to your own ranch environment.  When you buy replacement heifers, even though they may have good genetics, they may not adapt as well to your environment, and they may not fit your program as well.

“In recent years the semen companies have come up with improved ways to do the sex sorting and have increased their ability to offer just x or y semen.  This also improves producers’ success in using the sexed semen,” he says.  There are very few calves that don’t turn out to be the sex you wanted.  When you pay extra for this semen you want every calf to be the desired sex.

To know if use of sexed semen would be of economic value in a beef operation, each producer must figure this out for their own situation.  “What happened in our research study is that we did get more steer calves (which is what we were aiming for, to have more value when selling the calves) and that worked well, but the cows that did not conceive to the sexed semen or to the conventional AI and were bred by a clean-up bull had a later calf.  Those calves were a little younger and smaller.  If 50% of them are heifers and are going to be sold with the steers, the advantage we got was reduced.  It all equaled out, but it wasn’t a benefit,” says Bohnert.

He suggests using sexed semen strategically (on certain cows) to create replacement heifers.  “I think this is what would make it most beneficial,” he says.

Embryo transfer

Sexed semen is still more expensive than conventional semen, but there are situations when it is definitely cost effective.  As pointed out by John Hall, PhD (Extension Beef Specialist, University of Idaho, Superintendent of the Nancy M. Cummings Research, Extension and Education Center) it can be used effectively in embryo transfer and in vitro fertilization systems.  There are matings in which everyone wants a bull calf but nobody wants heifers, for instance.  Sexed semen gives an opportunity to have the desired outcome for this type of program in the purebred industry.

“For this, we tend to use a few more straws of semen than we would in typical embryo transfer.  When we breed the donor cows we have to use 4 straws of sexed semen versus 2 straws of conventional semen, simply because there are only 2.1 million sperm cells in a dose of sexed semen, which is only about 10% of normal,” Hall explains.

“Some companies have been doing embryo transfer and in vitro fertilization for a number of years, and have set up a way to take semen out of conventional straws, and sort those.  The resulting sort produces very low numbers of sperm, but they can use it for in-vitro fertilization, where dosage can be very small and still work.  They only need about 1500 sperm cells for in-vitro fertilization,” Hall explains.

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