Due to vaccination against bluetongue, the mortality in sheep that have received bluetongue has fallen on average this year from 75 percent to 13 percent. However, a caveat is noted. “Because many sheep have become ill, more than 40,000 more sheep have died than normal,” according to the Dutch Sheep and Goat Breeders Organization (NSFO).
Vaccination against bluetongue has not prevented sheep from becoming infected with the virus this year. And because the outbreaks started on June 14 this year – compared to September 5 in 2023 – many more animals have become infected.
According to Reinard Everts, sheep doctor and director of the NFSO, the median (the middle of the figures on the number of infected animals per company) in 2023 was 20 percent. This year it is much higher. ‘On farms that had the first sick animals at the beginning of July, the median was no less than 78 percent. So approximately four times as many animals per company became ill.’
Variation in disease symptoms and mortality
The symptoms of illness in the sheep varied greatly this year and there were still seriously ill animals despite vaccination. Other pathogens, such as the red abomasum worm, have also had an impact this year. Furthermore, mortality among sheep also varied greatly per farm. There are companies where mortality remained very limited and companies where mortality rose to perhaps 50 percent.
On average, the mortality of sick animals is lower than last year. The average figure for this year is around 13 percent. Last year this was 75 percent. The excess mortality from July 1 to September 26 amounts to 40,498 more animals than normal during this period.