- Many farmers accept barren ewe and abortion rates of 5-10%.
- Most lowland flocks could achieve a lambing percentage of over 170%.
- Both hill and lowland flocks with correct management should be achieving empty/abortion rates under 2%.
Enzootic Abortion (EAE) and toxoplasmosis are major causes of abortion in sheep.
Enzootic Abortion (EAE) (aka Chlamydia)
Abortions caused by Chlamydophila abortus usually occur during the last 2-3 weeks of pregnancy. When an ewe aborts, she sheds large numbers of the EAE organisms, infecting in-contact sheep. Newly-infected sheep will not show signs of EAE until approximately three weeks before lambing, when the placenta becomes inflamed, abortion occurs and the cycle continues.
An enzootic abortion storm can take up to 25% of flocks’ lambs. If a large proportion of the flock is already infected, the disease will cause ongoing losses of around 5% a year.
Toxoplasmosis, caused by Toxoplasma gondii, causes losses at all stages of pregnancy, resulting in infertility, empty ewes, abortions, stillbirths and weak/sickly lambs that usually die. Ewes usually acquire toxoplasma oocysts from contaminated cat faeces.
A single cat dropping can infect more than 100 ewes. Normally toxoplasmosis is a grumbling problem, reducing the number of lambs by around 6% yearly.
For farms where toxoplasma is present, vaccination has been shown to produce a 6.4% increase in the number of lambs, and a reduction in the abortion rate by as little as 2% will see the investment in vaccination pay for itself.
MSD Animal Health are now offering a fully funded diagnostic test. FlockcheckTM is available from your vet until the end of July to test your ewes for both EAE and Toxoplasma. Speak to your vet for more information about FlockcheckTM, and don’t forget to order vaccines in plenty of time!