A firsthand warning of what BTV-3 did to a dairy herd in Norfolk in Summer and Autumn of 2024.
One of the benefits of performing dairy farm audits for supermarkets and milk buyers in other parts of the UK is that I get to hear of other farmers’ experiences and views – and one I visited in May was the first dairy farm in the UK to have BTV-3 diagnosed.
There was an abortion storm in June/July 2024 in this 400 cow August to October block calving herd; 8 aborted cows were sampled for Neospora, Q Fever and BVD with only one positive Neospora found and 6 out of 8 positive for Q Fever (they were vaccinated for IBR and Leptospirosis). Consequently, they vaccinated for Q Fever.
During the calving season, there were 19 stillborn or weak, non-thriving calves (compared to 6 the previous calving season in 2023), which all tested positive for Bluetongue on APHA surveillance testing. Retrospective testing of the aborted cows’ bloods showed evidence of exposure to Bluetongue.
This is very similar to the findings of a study in Holland, comparing the incidence of premature births, abortions and calf mortality for dairy herds reporting an outbreak of BTV.
After calving had started on this farm in Norfolk, it was apparent that the milking cows were underperforming and the herd average daily production per cow was eventually calculated as 3 litres LESS per cow per day for at least the first 8 weeks after the first positive BTV-3 finding. This was far worse than the Dutch study who found a 1 litre loss per cow per day for the first 9 weeks after the first positive case on farms in the Autumn of 2023.
Hopefully, these findings and experiences in both the Netherlands and Norfolk will help highlight the potential consequences of BTV-3 incursion into your herd and thus help you to decide whether to vaccinate or not ahead of the next high-risk vector period – likely to be mid-summer onwards!
For me? …Vaccinate!
Written By Mike Kerby, Veterinary Surgeon
