Our BVD eradication scheme is coming very close to our target of national eradication and we are seeing the real animal health benefits on farms.
While we have not achieved national eradication, significant progress has been made. We can also learn valuable lessons for future programs and their implementation. For now BVD tissue tag testing is a key component of this program as we get closer to eradication.
Talking to vets up and down the country one thing they have really begun to reflect on, is how much more healthy cattle are. One area where significant improvements have been made, are in improving calf health. This improvement in calf health is one of the real success stories of the program.
BVD virus works by suppressing the immune system amongst other things. When we tackle disease we are always trying to raise immunity and reduce infection. Removing this virus from circulation is critical to healthy cattle farming.
Lets remind ourselves on BVD the facts
- BVD or bovine viral diarrhoea virus has an affinity for the reproductive tract of animals causing a range of diseases. It can cause severe immunosuppression in young animals. An animal’s immune system is so important in the fight against infectious bugs and pathogens.
- There are two strains of the virus but we commonly see BVDv type 1 in Ireland
- Animals who haven’t been exposed to the virus are extremely susceptible. This means while most Irish farms current risks are low it is extremely important to keep the disease out. Good biosecurity is important when we consider all infectious disease.
- The virus can spread orally or by inhalation, it will usually migrate to the ovaries and womb of female cattle. This is important because it can pass through the placenta into the young calf.
- The critical thing to remember is when this happens in the first 120 days of pregnancy the calf can become persistently infected. At this early stage the calf has no immune system developed so will it be persistently infected with the virus.
- These calves may not survive and abort or can be born persistently infected. The tissue tagging we currently do is to identify these calves early and remove them.
- Very occasionally the virus can cause deformities in the calf.
- The virus also can have devastating effects at breeding time itself, with dramatic increases in fertility issues. This can be seen with poor conception, early embryo loss and usually farmers will see very irregular repeats or cattle returning on heat.
- While persistently infected animals are a huge source of the disease, we can also get animals with transient infections. This is where healthy animals are exposed to the virus, they will show the effects like infertility or often in older cattle issues like respiratory disease.
- While the BVD virus can cause problems on its own, its effect on depressing the immune system opens the door for other viruses and bacteria. We can often see this where we have really bad outbreaks of pneumonia even in older cattle.
- Where a persistently infected calf is born they can really shed billions of viruses into the environment. These will then infect other calves in the herd (transient infections 3-4 weeks). This can be absolutely devastating where you get calf scours.
- BVD virus can also infect bulls , they will often get a temperature spike and can become infertile
- Remember good biosecurity pays long term, don’t buy in disease and always secure boundaries.
We are very close to eradication
Removing PI (persistently infected) animals has been a key part of the program through tissue testing. These animals are like virus factories and early testing and prompt removal is critical. While most of these PI animals will not make it to 2 years. Some will and can appear normal but will continually shed the virus.
Should I continue to vaccinate?
This is a question we commonly get asked about BVD. Vaccination has traditionally played an important role in the control of BVD. Vaccines are often administered in advance of breeding to protect the female animal and her future calf.
Every vaccine will have a specific protocol and must be followed. While the risk of BVD is extremely low now for most herds, our advice has been to talk to your own veterinary practitioners about your herds risk.
The challenge is now, as the vast majority of herds have no immunity or exposure and outbreak could be devastating. While we have BVD in our national herd even at very small levels, this makes anyone advising to drop a vaccine in a very difficult position.
Farmlab Diagnostics continues to develop its services to help vets and farmers have healthier livestock.
Farmlab Diagnostics is a leading provider of animal health diagnostic services to the Irish agri-food industry. BVD testing is just one of the many diagnostic services we perform in our lab. To check out the full array of diagnostic services go to www.farmlab.ie or contact us on (071) 9630792.
We also do special offers on larger volumes of testing, just pick up the phone to find out more.