Sheep: Reducing losses to abortion vital for a profitable flock
Published 17/02/2016 | 02:30
Whether a sheep farmer is in the red at the end of the year, all comes down to the number of healthy lambs per ewe.
It is essential to reduce or prevent any losses to abortion to give a farmer a fighting chance at maintaining a healthy gross margin per ewe.
There will always be some level of 'natural' abortion but once the rate goes above 5pc we need to start looking into the possibility of an infectious cause at play.
In practice I have seen the serious economic consequences of infectious abortion in ewes, not to mention the stress and upset for farmers pulling dead lambs from ewes.
There are numerous different infectious causes but the two most common and indeed preventable are toxoplasma and chlamydia or EAE the enzootic abortion of ewes.
Although toxo has long been the most common cause, chlamydia is steadily creeping up in incidence.
Toxo can cause significant early loss of embryos as well as the birth of dead and dying lambs, and chlamydia delivers similar results with abortion and the birth of weak lambs that often die in the first three to 24 hours.
I have seen abortion storms from chlamydia with 25pc and upwards of ewes aborting, and needless to say this decimation of the lamb harvest can be devastating.
I would strongly recommend early veterinary intervention right from the start.
The first abortion in an otherwise good year is often put down to 'a hurt' or 'one of those things', yet it is best to bite the bullet early and get these aborted foetuses with placenta and maternal bloods if possible to the lab via your vet.
For example if this first abortion is due to chlamydia, and possibly the start of an abortion storm, the sooner you know the better.
As an emergency measure armed with a prompt diagnosis of chlamydia injecting all ewes with long acting oxytetracycline is a fairly effective measure at halting the abortion and stopping spread of the disease.
Vaccination More importantly you are now aware of the problem and can plan an extensive vaccination programme with your vet for the following spring.
Mark and isolate aborted ewes from pregnant ewes.
Any subsequent abortions should also be sent to lab, not merely for surveillance but to also detect 'mixed infections'.
It is common to have both toxo and chlamydial abortions in the same flock simultaneously.
Vaccination, while not cheap, will last two years for toxo and three for chlamydia, and easily stands up to a cost benefit analysis.
Two important notes when handling aborting ewes are that both toxo and chlamydia are zoonotic and have serous consequences for pregnant women.
Also often extra lubrication is essential in delivering aborted dry foetuses.
The extra lube will facilitate delivery of the lamb while reducing damage to what is still a viable and healthy ewe.
On a different note, there is another entirely avoidable cause of abortion that unfortunately is on the rise, that of dog attacks.
I have attended many flocks after attacks and what I face with the farmer in these situations is horrific, with not only dead ewes but ewes savaged to the extent that euthanasia is the only option.
Invisible in the midst of this drama is the ewes that have survived but abort soon after their ordeal.
I'm not aware of any formal studies into lamb loss post attack but I know from experience it can be significant.
Hopefully, with the advent of compulsory microchipping in dogs, more owners of these rambling canines can and should be held to account for such attacks.
I'm a vet, not a lawyer, but surely a severe financial penalty for the irresponsible owners of these dogs can and should be imposed?
Niall McDonald is a vet based in Co Meath