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There are several ways
to check cows for pregnancy, including rectal palpation,
ultrasound, and blood samples. The latter method is relatively
new, but becoming more widely used by beef and dairy producers
as a growing number of laboratories are now able to process the
blood samples. The technology was originally developed by Dr.
Garth Sasser, University of Idaho (Moscow) more than 20 years
ago. He discovered a protein called Pregnancy Specific Protein
B, produced by the placenta. He later licensed the blood test
process (which he named BioPRYN) and founded a company called
BioTracking. Originally the test was done in elk, but is now
done in almost any ruminant species including cattle, sheep and
goats. Blood
test for pregnancy started out with a radioimmunoassay (more
expensive), but the technology developed in recent years uses an
enzyme-linked immunosorbent assay (ELISA) to evaluate the blood
samples. It is not as expensive and also more reliable than
earlier attempts at pregnancy diagnosis that evaluated blood or
milk for progesterone or other hormones that can occur in open
animals. The BioPRYN (Pregnant Ruminant Yes/No) test is also
simpler technology that anyone can use.
According to Jeremy
Howard at BioTracking, the company is growing rapidly because a
wide mix of producers are now using the blood test. “To give you
an idea of how this use is growing, in 2005 our company
processed 85,000 total samples. In 2006 we did more than
207,000, and during the first 4 months of 2007 we’d already done
more than 110,000 samples,” says Howard. The company now has 14
affiliate labs around the U.S. and Canada.
Many beef producers
use the test in heifers, enabling them to hit the heiferette
market with open heifers. “We can detect pregnancy as early as
30 days post breeding. When blood is drawn and shipped to us,
it’s a 27 hour turnaround on our end. Many producers check their
heifers 30 days after bull removal or after AI, and any that are
open can be sold as heiferettes. We also have producers using
the blood test 30 days after they AI their cows. In a registered
herd they may keep the bulls out of the herd for a certain
period after the cows were bred by AI. With this test we can
tell them which cows conceived to the AI and which cows were
bred to the bulls,” he says.
“We have producers
with large numbers of cows, like one in Texas with 5000 cows; he
sends us blood samples every time he pulls cows off the range,
to detect the open ones,” says Howard. The largest growth in use
of the test is in the Midwest and south. “Here in the Pacific
Northwest we are blessed with a lot of large animal
veterinarians, whereas in many other states this is not the
case. We have customers in some states where their nearest vet
is 2 hours away and won’t come to their ranch to palpate cows;
they have to truck their cows to the vet. This is where the
blood test becomes much more convenient,” he says.
Regarding accuracy,
many people feel the blood test is better than palpation or
ultrasound. “If we tell you a cow is open, we are 99.9 percent
sure she is open. If we call a cow pregnant, this is a 95
percent accurate determination,” says Howard. You will always
have a few cows that resorb the embryo or abort a fetus after
they were checked pregnant. If you check them early in
gestation, there will always be some that don’t end up pregnant.
The test can detect
pregnancy any time between 30 days post breeding and the day she
calves. In a cow that has already calved, as opposed to a heifer
being bred for the first time, she must be 90 days post calving
in order for the test to be accurate. If a cow breeds back
quickly after calving (conceiving 40 to 50 days after calving)
you should wait a little longer than 30 days after breeding, in
order to really know if she’s pregnant.
“The pregnancy
specific protein B level in her body is so high before calving
that there will still be some in her bloodstream for awhile
after calving, and we can detect it up to about 80 days after
she calves,” explains Howard. This could skew the test results
until this protein has disappeared.
Fred Muller, DVM (Sunnyside, Washington) has been using this
technique in his practice since 2002, and has his own lab (Ag
Health Laboratories) where he can process the blood samples. His
clients include dairies as well as beef producers. “For the beef
producer, it has been very helpful for shifting preg checking
(for AI pens) to a weekly program. Sometimes it’s difficult to
get veterinarians to show up every 1 or 2 weeks to palpate cows.
There is a lot of value, if you are trying to get open cows
rebred as quickly as possible, in doing weekly preg checks,” he
says.
“The blood test is
helpful, since you don’t have to work around the vet’s schedule;
the producer can take the blood samples. The producers in this
area were well trained, already, in taking blood samples,
because of some of the other sampling they do--like for Johnes
disease. They were used to that, and also accustomed to giving
GnRH shots from a list of cows that haven’t shown heat, or open
cows--going down through the AI pens and giving the shots. So it
was really easy to add the open cows (from the blood test) to
that list,” says Muller.
“Some producers and
vets think it would be a major undertaking to go back later and
give shots, but in our area this has not been an issue. Some
people are finding this very helpful in what they are trying to
do. It is a very useful program for certain herds that it fits
well for,” he says. For other producers it is never going to
fit; they are not intensely getting cows rebred or they don’t
like to use synchronization programs, or they are depending on
bulls for the breeding. There are many herds it won’t work for,
but in others it is working very efficiently.
In herds with
intensely managed reproductive programs, it’s a big help because
you don’t need to have a vet out all the time to palpate or
ultrasound the cows. “The beef side of this industry has shown
the largest growth in use of this method, the last couple years.
Many producers don’t like to schedule or pay for vets to preg
check, and some vets are turned off by producers doing this
blood test on their own, but my experience is that many
producers are not using vets anyway. A lot of them are using lay
people to palpate cows. I have a lot more confidence in the
accuracy of the blood test than I do in some of the lay people
who are palpating cows. I think this blood test is a lot better
than most of the other non-vet options that are being utilized,”
he says.
Ranchers who just
work cows one time and split off the open cows to sell won’t
find it useful. Some large commercial operations are not going
to use it. “But for the rancher who doesn’t find it difficult to
recapture the cows to reprocess in a couple weeks, it doesn’t
matter if they get an answer within a few days instead of when
they are in the chute,” says Muller.
Some beef producers use it to get an early answer on whether an
animal settled. “If a rancher is artificially inseminating the
heifers, and wants to know which ones conceived to AI, after the
heifers have been bred for 30 days or more they can bleed them
and get that answer. Then they know which ones were settled to
AI. If the open ones (at that time) come up pregnant in the
fall, they’ll know they were bred to the cleanup bull,” he says.
“A lot of people
use it early in the season. It may not be quite as accurate when
using it late in the fall. If the cow is 4 or more months
pregnant and then aborts, there’s some residual hormone in her
bloodstream and the test might be inconclusive. You might think
she is still pregnant. There can be a false positive and you
need to keep this in mind. Because of that, early testing in the
first 3 months of pregnancy is a little more useful; you have
less errors if you’re testing in the first trimester than if
testing in the third trimester or late in the second,” explains
Muller. “If a cow is only a month or 2 pregnant and aborts, and
you test her within a couple weeks, the hormone drops back down
to open cow levels real quick. But if she’s 4 or 5 months
pregnant and then aborts, she’ll have residual hormone longer.”
This test is more accurate than palpation. “Even the vets who
are palpating lots of cows make some errors. Regarding cows that
aborted a large fetus, a person palpating the cow may think she
is still pregnant—especially the less experienced lay person. It
is fairly easy to mix up a large uterus of a recently aborted
cow with a large uterus of a pregnant cow,” says Muller.
“It’s like most
tests; it works very well for certain herds in certain
situations. It just depends on what your management goals are.”
It’s one more tool that can be a benefit. More stockmen are
starting to use it, as they learn about it and see others using
it successfully. As with most new technologies, there is usually
skepticism at first. It takes time for people to see the results
and realize that other producers are using it successfully.
There are a lot of
producers who don’t have good veterinary services available
because they are too far from a large animal vet. “In order for
it to be worth the vet’s time, he/she may charge $200 just to
drive the 200 miles to get there, plus the regular fee. If you
have a good vet that’s close by, and doing a lot of cattle work,
you’d probably try to use the vet,” he says. But if that’s not
an option, the blood test is an attractive alternative.
A Wagyu breeder in
New Mexico has been using this method for 2 years. Stanley
Hartman, manager of the Lone Mountain Ranch at Golden, New
Mexico (30 miles northeast of Albuquerque), says they were
originally an Angus-Brangus commercial cow/calf operation, and
only preg checked cows once a year at weaning time. “A few years
ago the owner of the ranch ate a Wagyu steak in Los Angeles and
was very impressed--and told me to get rid of our Angus bulls
because we were going to start breeding Wagyu. I thought he was
crazy, but now I think he knows what he’s doing,” says Hartman.
“We bought 2 Wagyu
bulls and bred them to our cows. That fall we bought 9 Wagyu
cows, and started flushing them and transfering fullblood
embryos into our commercial cows. Then we came across the
website for BioTracking, where they can check for pregnancy at
32 days. I thought that was really a good tool, because we could
preg check the recips right away. If they didn’t take, we could
turn around and use them again,” explains Hartman.
“Before this, the
fastest we could turn them around was 90 days. And even if you
get someone who’s good at preg checking they are still going to
miss one once in awhile. I thought I had a really good guy, but
later discovered that his accuracy was only about 70 percent,
palpating at 90 days. The way I found that out, he called some
of our Angus cows open--but when I went to start syncrhonizing
them for our recip program and gave them a shot of Lutalyse,
they aborted,” he says.
After he began doing embryo transfers he started using the blood
test for pregnancy checking at 32 days. “That really helped, in
our program, so we could recycle any open cows quickly instead
of waiting 90 to 120 days to check them before we could put
embryos in them again,” says Hartman.
“The blood tests
have been really accurate, so far,” he says. Once in awhile a
cow will lose a pregnancy; she will test pregnant at 32 days and
then resorb or abort the pregnancy sometime between then and
when she would have calved. So Hartman typically checks cows at
32 days and again 30 days later--since with an embryo transfer
you can lose some of them during the second month. So he checks
them twice, and if he has any questions on a certain cow he will
check her a third time, since it doesn’t take long to put her
through the chute and draw a little blood to send off.
He sends blood samples to the lab at Moscow, Idaho, and has the
results 3 days after he ships it. “It’s also cheap, compared to
palpation. The guy who preg checks charges $3.50 per head, and
the blood test costs only $2.25. Most vets don’t like doing it
because it costs so much for them to drive out here, and their
time is also valuable. You can take a cow to the sale barn to be
preg checked, since they check all the cows that go through, but
they’ll charge you $5 to $10 to do it,” says Hartman.
Being able to take
a blood sample and send it off has saved him time and money.
“I’m breeding a bunch of Angus heifers right now to Wagyu bulls
so we can get some progeny data on their calves. I’ll blood test
them to see which ones are settled. Whatever turns up bred, I
can pull those out of the pen and kick them out on pasture,
since right now they are penned up with different bulls. That
way I won’t have to feed all of them for 90 days before I can
figure out whether they are bred or not,” says Hartman. He can
run them through every week to preg check via blood test, and
whatever ones are bred can be sorted out to go to pasture.
“It’s a bit of work
to run them through that often, but it costs more to keep
feeding them hay than to put them through and blood test them,”
he says. Sorting them in a timely fashion will save a lot of
hay, and labor in feeding them. There are many advantages to
being able to preg check this early, this cheaply.
Most producers
merely need to figure out how the blood can fit their own
operation. It’s a lot easier and simpler than palpation, and
easier on the cattle. It’s also safer for the embryo or fetus;
some cows have been known to abort after rectal palpation.
“All you have to do
is raise the tail up and take a blood sample. I take it out of
the jugular vein in the neck; it’s easier for me to hit the
jugular than the little vein in the tail. We work our cattle a
lot more than we did our commercial herd. We used to just run
them in when the calves were 2 months old, to ivermec the cows
and brand and vaccinate calves--then kick them out on pasture
and not do anything else with them til weaning time in November.
But now we are transferring embryos every month and working cows
in the corral, so we have a really good facility. It’s no big
deal to put them through the chute, push their head to one side,
and take blood from the jugular. I can do 100 of them in about 2
hours,” he says.
Sheri Wadenkamper
(Lets Go Work Ranch, in Hermiston, Oregon) says they blood test
their registered Angus heifers when they AI them after
synchronizing, to determine which ones did not settle to the AI.
“We can pick them up a lot quicker this way, and have a chance
to rebreed them. We also use the test on all our first calf
heifers, 30 days after they are bred. Since this is the age
group most likely to not settle, this gives us a chance to use
cleanup bulls on the ones we find open. Being able to check them
this quickly, we can determine how may cleanup bulls we need,”
she says.
“We don’t blood
test all our mature cows--just the ones that show heat after
breeding. We had a couple last year we thought were pregnant but
were showing heat again. We took a blood test and could see the
protein level was dropping,” says Sheri. But it pays to check,
because some cows show false heat even after they are pregnant.
It’s not a good idea to just go ahead and rebreed them just
because they showed heat, because this may cause the cow to lose
the pregnancy.
Sheri is the one who draws the blood on their cattle. “We take
it from under the tail, and it helps to have someone hold the
tail for you. Once you know the right spot, it’s very quick and
easy, and a lot quicker than palpating a cow. We often do the
blood test in conjunction with working the cows to put in fly
tags or use a pour on. We worked 330 head recently and of that
group I picked out 40 I wanted to draw blood on--and that went
very quickly compared to having to stop and palpate them. And we
couldn’t have used palpation as early as 30 days, anyway,” she
says.
“The first time we
did it, we had our vet work with us to show us the process, then
it was simple to do it ourselves. We order the needles and vials
from a catalog order supply company,” she says. The blood
samples don’t have to be refrigerated; they are fine at room
temperature until they are sent to the lab.
“I think this test
has a lot of merit. For instance, if we see a cow show heat
during the summer, we can run her into the corral and take a
blood sample--and not have to haul her to the vet to see if
she’s open,” says Sheri.
And since they
breed their cows so early, finding the open ones early gives
them an option to rebreed them--to sell to a later calving
market. “We can sell that cow, rebred for a later calf, at
higher market value to someone who calves later than we do,
rather than having to sell her as an open cow at weaning time.
We cull hard; a cow has to stay on our schedule to stay in our
herd. But she might work fine for someone who calves later.”
There are many ways to utilize the blood test preg check to fine
tune most breeding programs. |
