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BVD - have you got it covered ?

bovilis supplied(copy)It is great to see that the level of awareness to BVD has risen sharply in the past five years, driven by increased awareness by vets and LICs BVD testing packages.
We now have over 70% of our clients either vaccinating, monitoring or both, which is a great step up. However, sometimes you think you have got things covered, but a lack of attention to detail can leave you exposed to risk.
Below are some of the more common areas where we have seen a lack of attention to detail leading to problems with BVD on farm:
BVD monitoring but not vaccinating:
Many farmers are now relying on the LIC bulk milk monitoring program as a method of getting an early warning of BVD infection in their herds. This is a great program, but there are areas where this can fail to detect infection before it has become established.
Reasons for breakdowns include:
  • Milking PIs can be missed if they are on dump buckets or are late calvers that are not in the vat at the time of testing. Statistically PIs have a good chance of being on antibiotics or being late calvers
  • Detection of non-milking PIs can be retrospective- e.g. the effect of a purchased bull which is a PI may not show up until there is a late season antibody rise on the milk. By this time BVD may have wreaked havoc with the herd’s empty rate and calving spread for next season
  • Risks from non-milking PIs include exposure to untested purchased or lease bulls (have those bulls really been tested?- Ask to see the paperwork!), beef animals on farm, calves grazing at home and over the fence contact with neighbouring stock (how often does a neighbours animal end up on your side of the fence?)
  • Your rising two year old heifers are not being monitored. Statistically this age group is far more likely to have PIs amongst them. For this reason, unless all heifers have been tested, it is safer to vaccinate this group prior to mating. Where heifers are at a graziers’, being run with other peoples stock, vaccination is a must.
In summary, all farms should be doing some sort of BVD monitoring- whether using the full LIC package or if vaccinating, a yearly bulk milk sample at mating time,  but don’t assume that if you are monitoring you are not at risk. Most farms have some uncontrolled biosecurity risks, and in many cases, vaccination is the safest way to handle that risk.
BVD Vaccinating:
Even when you are vaccinating the herd and heifers, there are still things that can go wrong! Some of the more common risks include:
  • Milking PI cows can reduce herd production by 2-3% even in vaccinated herds. This is likely to be due to the ‘biological cost’ in energy required to mount an immune response to protect them against BVD. Whilst they will be protected against foetal loss and the birth of PI calves, this can still cost them in reduced production
  • Milking PIs will always give birth to PI calves. The sooner you can remove PIs from the herd, the sooner you close the risk of PI calves being born which can impact on young stock health and fertility. Timing of vaccination- the vaccine has a six month foetal protection claim. This means the first six months of pregnancy is covered if cows are boosted one month before mating. We have had one instance where a PI calf was born out of a vaccinated herd where the booster was given too far before the start of mating. For this reason, heifers should have their second vaccination one month before mating and cows should have their booster not more than one month before mating
BVD is a complicated disease, and the best control strategy for your farm depends on a lot of different factors including your farms biosecurity risks and on how risk averse you are. If you are not vaccinating or doing regular monitoring, you should be doing at least one and maybe both!  This is one topic where it is well worthwhile discussing your strategy with one of our vets to make sure you have the best fit for your farm.