Complex Vertebral Malformation (CVM)
Aug. 10, 2001 Select Sires Memo
MEMORANDUM
TO: Board of Directors, Member Managers, Member Marketing Directors, Member
Communications Coordinators, Select Sires Staff, John Schouten
FROM: Dave Thorbahn, general manager, Select Sires Inc.
SUBJECT: New Select Sires Policies Established to Help Manage Potential
Impact of CVM
DATE: Aug. 10, 2001
During a conference call yesterday, the Select Sires Inc. executive
committee approved new sire-selection and marketing policies that will help
us manage the potential impact of Complex Vertebral Malformation (CVM). Even
though the industry still has more to learn about this genetically
transmitted condition, we believe that — as the A.I. leader in North
America — it’s important for Select Sires to take careful, considered steps
to responsibly reduce the incidence of CVM.
As background, in my July 24 update memo I shared a press release from NRS,
The Netherlands, announcing its conclusion that CVM is caused by a single
recessive gene. Since then we have obtained and analyzed details about the
supporting research. This large-scale study of breeding records tracked more
than 500,000 inseminations of cows that were sired by CVM-carrier bulls. The
service sires included 38 CVM-carrier bulls and 77 non-carrier bulls. The
services to CVM-carrier bulls resulted in 5.83 percent fewer live calves
than were produced by services to non-carrier bulls. Theoretically speaking,
if CVM is caused by a single recessive gene, we would expect to see 5.75
percent fewer calves. In addition, each of the 38 CVM-carrier bulls had a
lower rate of live calves than any of the 77 non-carrier bulls. This
analysis, coupled with the fact that the current DNA marker test has yet to
find a live animal with a homozygous genotype, supports the NRS findings.
As Select Sires takes steps to manage the potential impact of this genetic
condition, it’s important to avoid overreacting. To put this in perspective,
I find it helpful to ask the question, "Practically speaking, what might CVM’s economic impact be?" To calculate the impact, we can make these
assumptions:
- Based on research to date, it appears that when a fetus is CVM-affected,
it results in abortion in about two-thirds of the cases and a stillborn calf
one-third of the time.
- The gene frequency for CVM is about 4 to 5 percent, if 7HO543 Carlin-M
Ivanhoe BELL is the primary source of the genetic defect.
- Approximately 2 percent of the pregnancies created by randomly mating a
CVM-carrier bull to the current cow population would be affected with CVM.
Based on these assumptions, to recoup the losses from increased abortions
and stillborn calves, the worst-case scenario is that each remaining
daughter of a CVM-carrier bull will need to generate about $50 more during
her lifetime. This is a significant cost, but it can be overcome by
leveraging advantages in other selection traits. By maintaining pedigree
information and using a mating program like Select Mating ServiceTM (SMSTM)
to avoid inbreeding, producers can reduce the incidence of CVM in their
herds.
With this new information and input from all member organizations, Select
Sires is implementing measures to help reduce the potential impact of CVM
for dairy producers working with Holsteins. They include the following.
- We will continue our commitment to identify lineup sires that have
transmitted CVM or are designated as carriers of CVM based on DNA marker
testing. Currently this includes 7HO5408 Peckenstein Elton CURTIS-ET as a
"carrier of CVM" based on testing. It also includes 7HO5234 Ricecrest
BRANDON-ET because his DNA marker test results declared him "most probably a
carrier of CVM" and he has sired a CVM-affected calf. This information will
appear in all future communications about these sires, including sire
directories, price lists, articles and advertisements. Once Holstein
Association USA establishes a label for this genetic condition, Select Sires
will adopt that as our standard identification.
- Within the next few weeks we will submit tissue samples for our entire
Holstein lineup for CVM testing. As results become available, they will be
added to www.selectsires.com. We expect to have all test results in hand by
November proofs. All other Holstein bulls will be tested prior to entering
the active lineup.
- We recognize that until DNA marker test results are available, some
customers may want to consider a sire’s theoretical probability of being a
CVM carrier (based on pedigree analysis) as a part of their purchase/mating
decision. This information will be made available to sales representatives
and SMS evaluators to share with customers.
- Beginning immediately, all young Holstein bulls scheduled to enter the
Program for Genetic AdvancementTM (PGATM) or become a Super SamplerTM will
be tested for CVM using DNA market technology. We recognize that this will
be a challenge because of turnaround time – currently the only laboratories
licensed for this diagnostic test are in Europe and it takes at least a
month to receive results. Our intent is to cull the CVM-positive bulls with
low parent averages. While our sire department will do all it can to
purchase additional genetically superior bulls to maximize the opportunity
to cull CVM carriers, we will sample some high parent-average calves that
have a chance of being CVM carriers during a transition phase.
- Next week Chuck Sattler will send a communiqué to PGA cooperators,
providing background about CVM. Also enclosed will be information about any
CVM marker-test results we have for progeny-test bulls whose semen has been
distributed recently. If a cooperator is uncomfortable using semen from a
bull that has been designated a carrier of CVM, then Select Sires will
replace that semen upon request.
Through all of this, it’s important to remember that the key to controlling
CVM will be avoiding carrier-to-carrier matings. The "CVM gene" will
continue to be just one among 10,000 genes that influence the performance of
Holsteins. That’s why culling all CVM carriers from the Holstein breed is
likely to be more costly than the losses due to CVM. Managing this condition
will become easier over time as fewer CVM-carrier sires are progeny-tested.
You’ll be glad to know that, at its recent annual meeting, the National
Association of Animal Breeders reaffirmed its commitment to continue
researching CVM’s mode of transmission. The research project still is in
need of cows that have produced CVM-affected calves. Whatever you can do to
help identify CVM-affected calves will assist greatly in advancing our
industry’s understanding of this condition.
I believe there are two positive messages we can take away from this
industry challenge: 1) evolving technology has enabled the industry to
discover a problem that likely has been around for awhile; and 2) through
diagnosis and selection, we have the tools to fix the problem. As we work
through this challenge, know that Select Sires is doing everything it can to
manage the negative effects of CVM, basing our actions on sound science.
Please feel free to share this memo with members who have questions. As we
learn more about CVM, I will continue to forward that information to you.
Select Sires Inc., 11740 U.S. 42 North, Plain City, Ohio 43064 / Phone: (614) 873-4683 Fax: (614) 873-5751
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