LIVESTOCK | DISEASES
Beware threat of BVD in sheep BY: ANDREW SWALLOW
N
ew evidence Bovine Viral Diarrhoea (BVD) is present in New Zealand sheep flocks has prompted vets to warn farmers attempting eradication in cattle to be “mindful” sheep can be infected too. Tests on 270 ewe hoggets across 18 sheep and beef farms, 15 from each farm, found 17 animals with antibodies to pestiviruses, indicating probable* exposure to BVD. All came from two farms that were among nine selected for the study because they were known or highly suspected to have BVD in their cattle herds. The other nine farms were selected for being considered BVD-free. “These findings highlight that farmers who are trying to eradicate BVD from their
cattle should be mindful that the infection may also be circulating in sheep, and both populations should be considered a possible risk to each other for generating transient and persistent [BVD] infections,” concludes the New Zealand Veterinary Journal report by Massey University Associate Professor Carolyn Gates and colleagues. Speaking to Country-Wide about the study, Gates warned BVD in sheep causes “many of the same problems with reproductive performance and poor growth rates” as in cattle. Consequently, it could be causing even greater losses than the $150 million/year currently estimated, making eradication from New Zealand even more cost-effective than economic models have predicted. The disease’s presence in sheep shouldn’t make much difference to how hard it will
be to eradicate either, as it generally doesn’t persist in sheep. “Outbreaks in sheep flocks are expected to burn out much faster because the virus isn’t as well adapted to that species,” she explained. “There is much more risk of cattle spreading BVD to sheep than the other way around.” Like calves, lambs infected with BVD in the womb can become persistently infected (PI) and shed large amounts of the virus for life. However, unlike PI calves which often survive several years, most PI lambs die within weeks or at most a few months so don’t have as many opportunities to infect other animals. Besides the loss of those PI lambs, ewes which become infected (transient infection) may have reduced fertility, abort, or produce lambs with birth defects.
EWE WANT A RAM WELL HERE WE ARE
CALLTHE THEPETERS PETERS GROUP GROUP CALL www.petersgenetics.conz TREVOR PETERS
03 446 6030 027 201 4490
100
CLAYTON PETERS
03 204 8817 027 222 4421
MORGAN PETERS
03 204 8849 027 440 7411
JUSTIN WALLIS
03 976 6509 027 225 8330
Country-Wide
October 2020