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• Danish researchers have identified a new genetic recessive which results in stillborn calves with severe curvatures of the spine.
• A DNA-based test is said to be 98% accurate in detecting carriers of the undesirable allele.
• Avoid use of bulls known to carry undesirable alleles for genetic abnormalities.

Have you been having more stillborn calves? One possible explanation is a recently identified undesirable recessive in Holsteins. Some of your cases of stillbirths may be a result of a genetic abnormality called complex vertebral malformations (CVM). This condition has been identified by researchers J.S. Agerholm, C. Bendixen, O. Andersen and J. Arnbjerg in Denmark. They were able to find CVM because the Danish cattle population has been monitored for hereditary defects since 1989. Malformations have been observed during mid to late gestation in aborted fetuses, prematurely born calves, stillborn calves, and neonatal calves. No calves with the condition have been known to survive past birth. Radiological examination is desired for most conclusive physical diagnosis. However, visual evidence might include a shortened spinal column and contracted or rotated joints above the pasterns.

A DNA-based test for CVM has been developed and is currently awaiting patent approval. This test identifies carriers of the undesirable allele for CVM through the use of genetic markers. The test is available from the Danish Institute of Agricultural Sciences. For further information or questions about the test, contact Dr. Christian Bendixen (E-mail: christian.bendixen@ agrsci.dk). More information on CVM is available at the following Danish web site: http://www.lr.dk/lr/system/vislrnyheder.asp?maxdays=30&expand=yes

On Nov. 1, 2000, at this web site, two files had information about CVM. The first was 'CVM-arvelig defekt hos Holstein kvaeg' which contained a brief description including a four page article in English with pictures (http://www.lr.dk/kvaeg/informationsserier/nyheder/CVM.pdf). The second file was 'DNA-test udpeger sortbrogede tyre med arvelig defekt' which had a link to 'se testresultaterne pa LandbrugsInfo'. Lists of carriers and non-carriers were available from this link. The implication was that additions to both lists would be made periodically. When I accessed the lists on Nov. 1, 2000, 11 bulls were identified as carriers and 36 bulls were identified as tested free of the condition. Only one US bull was on either list and that bull was Carlin-M Ivanhoe Bell, identified as a carrier. The notation to designate carriers was CV. Bulls tested to be free of the condition were identified as TV. Of the bulls tested, 45 were from Denmark, including all of those identified as non-carriers.

Samples from many US bulls with suspect pedigrees have been submitted for testing. Hopefully, more information on specific US bulls will be available soon. Check the web sites indicated previously to obtain the latest information.

Bulls known to be carriers of undesirable recessives should not be used in a breeding program. The exception to this recommendation is in those few situations of a contract mating to produce a young sire for genetic advancement. In this rare situation, sons produced from the contact mating should be screened for genetic abnormalities and only non-carriers should be allowed to enter a progeny-test program. The population of dairy cattle can not afford to carry genetic abnormalities.