Page 16 - Tarangower Angus Catalogue ebook

MANAGING BVD IN YOUR HERD GENETIC DEFECTS IN ANGUS
BVD is a Pestivirus that infects cattle, usually between the ages of 6 Arthrogryposis Multiplex (AM) and Neuropathic Hydrocephalus
months and 2 years. (NH) Contractural Arachnodactyly (CA)
The main impact of BVD is on breeding animals. AM. NH and CA are simple recessive gene defects, caused by the
How do cattle contract the virus? presence of a single pair of inherited genes. The red gene in Angus cattle is
• The virus is spread by direct contact with an infected animal. a common example of recessive inheritance-the gene must be present on
• A Persistently Infected Carrier (PI) animal is born after their mother is both sides of the pedigree for full expression.
infected for the first time with the BVD virus, between 1 & 4 months If a carrier sire and a carrier dam are mated, 25% of the progeny will be
of pregnancy. clear of the defect, 50% will be carriers, and 25% will be affected.
• All calves born to PI animals will be PI’s themselves. A DNA test has been developed to identify earlier animals so these defects
can be eliminated from the breed.
Is BVD treatable?
The disease is not directly treatable. In normal healthy animals, BVD is After such DNA testing, you will be given one of two results;
usually a short lived disease, which the animal recovers from by itself.
• Normal healthy animals may scour for’ a few days and experience a AMF, NHF or CAF = tested free of the gene
check in growth rate. AMC, NHC or CAC= tested carriers of the defect.
• Bulls may be temporarily infertile. But, to assist with the idenlification of carrier animals (prior to DNA testing)
a ‘probability test’ has been developed -using updated test results and
• Pregnant cows or heifers, depending on the stage of pregnancy may
show empty, abort the foetus, give birth to weak, sickly or deformed animals’ pedigrees, known as Geneprob. Geneprob will identify ‘at risk’
calves, give birth to PI carrier animals or give birth to a normal antibody animals in the breed database and assign them a status for AMS or NHS
positive calf. as follows;
AMFU, NHFU and/or CAFU =free by pedigree inference, untested
• PI carrier animals often appear normal until they develop ‘mucosal
disease’ (fever, ulceration of gums, oesophagus and entire digestive AMS %, NHS% and/or CAS% = a suspected carrier(% = level of
tract). Mucosal disease in PI animals is always fatal and all PI animals suspicion) but un-tested. Requires testing to validate true status.
should be cuned as soon as they are identified. AMF ,NHF and/or CAF =tested free of the defect
AMC, NHC and/or CAC = tested carrier of the defect.
The only way to detemine the BVD status of your herd is by blood testing. These GeneProb analysis tests are perfonned every seven days.
Discuss options with your vet.
Genotyping for these mutations should, with 100% accuracy, expedite
To protect your herd against BVD it is advised to bring in no outside animal elimination of these genes from the Angus population. If you are unsure of
unless it has been tested clear of the BVD virus. This is particularly true of any aspect of these genetic defects please enquire of your bull supplier or
breeding bulls. Most stud breeders have BVD programmes in place and do ring the NZ Angus Association on 06 3234484.
pre-sale BVD/EBL testing. Always check before you purchase a bull. To
avoid temporary infertility in your sires if exposed to BVD while out with the GENERAL MANAGER
Angus New Zealand Inc
cow, always give them a booster vaccine prior to mating.