You may have recently received a phone call from your Anexa FVC Vet with your final results from the LIC BVD Bulk Milk Monitor Pack. Many farms experience a rise in antibody levels (or SP ratio) at the end of the season, and this pattern may have been consistent with previous seasons. This rise in SP ratio can be due to low milk volume at end of the season, but a rise in SP ratio of greater than 0.3 should trigger some further discussion with your Vet due to the possibility of a BVD breakdown.
The graph is an example from a local farm that had just such a BVD breakdown. The sharp increase in late season antibody levels (circled in red) was so high, that their Vet during the 2014 to 2015 season repeated the antibody titre to make sure it was real. And it was!
The following spring, based on the information provided by the autumn antibody test, all the 2015 born keeper calves were ear notched and 8 high value replacement heifers were BVD Persistently Infected (PI) Positive. How many bobbied bull calves were BVD PI’s? We will never know. The spike in autumn antibody was likely from BVD exposure from the bulls used for natural mating or over the fence from the neighbouring farm. This farmer now BVD blood tests all bulls on arrival to his property, he doesn’t trust blood tests from outside suppliers/agents. If this late season antibody test hadn’t been done, then the PIs would have only been picked up two years later when they entered the herd causing massive reproductive and production losses.
Make sure you speak with your Vet about your end of season result and sign up for next season’s Monitor Pack at the same time. To be certain that no BVD virus got into your herd during mating, the best practice is to ear notch the 2017 keeper calf crop to make sure you are not raising any PI BVD calves. This 2017 to 2018 season, Anexa FVC will be offering a BVD ear notching service during calf disbudding. Please ask your Vet about this service.
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