Most sheep farmers lose 1-2pc of lambs from lambing to sale. In the past low lamb prices did little to encourage preventative measures. Price increases have changed circumstances, however.
Most mid-summer deaths can be attributed to clostridial diseases or pasteurellosis. Pasteurellosis can also reduce lamb thrive.
In an extensive trial carried out in the UK in 2003, it was shown that for every sheep in the flock that died there was a further cost, equivalent to another dead sheep, when treatments of ill animals, loss of performance and associated labour were taken into account. I have never vaccinated against clostridial diseases or pasteurella in the past but intend to do so this year, probably giving the first dose in early May when the lambs are being given their first worm treatment.
Lambs are given the first worm dose (against nematodirus) on the basis of the annual forecast, age (around five weeks) and faecal egg counts. Faecal egg counts indicate the presence of egg-laying adults and larvae may have already done damage. In most years the annual forecast (still awaiting this year's forecast) suggests that lambs be dosed early May to mid May.
I normally dose during the first week of May. I take faecal samples from about the third week of April and may well go in earlier should samples contain eggs. I gather further samples from about 14 days from the first dose in order to ascertain if a further dose is required.
Dosing before the infective larvae hatch and are consumed by lambs is a total waste of time and money.
There seems to be some confusion as to the most effective anthelmintic product to use against nematodirus. I normally use a benzimidazole (white) or levamisole (yellow) based product for this dose on the basis that:
1) There is no evidence of anthelmintic resistance to any of the recommended products
2) These anthelmintics give a wide spectrum of control being effective against both adults and immatures. Some of the macrocyclic lactone injectables are not indicated for the immatures.
3) None of the products available have any residual activity against nematodirus. Using the white and yellow drenches early and the macrocyclic lactones (clear) later will help to prevent the build-up of anthelmintic resistance.
This brings me to an interesting study carried out by Teagasc Athenry and presented at the 2011 Research Forum. Lambs from two large mid-season flocks were weighed at weaning and were then assigned at random, within each flock, to one of four anthelmintic treatments -- a macrocylic lactone (clear) product with residual activity, a levamisole (yellow) product, a Benzimidazole (white) product and Monepantel (orange).
The lambs in each flock were then managed as a single group and were weighed again after 42 days. Lambs dosed with the clear product with residual activity grew faster and were 0.7kg heavier than those dosed with the other products, which all resulted in similar performance.
The results of this study suggest that when dosing lambs at weaning there is a benefit to using a product with residual activity.
While on the issue of flock health, I have a small request. Each year I receive a number of calls concerning the antibiotics I use for specific conditions. About two months ago it was 'how effective is pen-strep against listeriosis?'
When challenged as to why he did not consult his local vet, the reply was 'my vet has no interest in sheep'. Similar calls, anecdotal evidence picked up during farm visits and at meetings and in conversations with vets would suggest that the most appropriate antibiotics are not always used. When veterinary surgeons write about animal diseases they very often conclude that treatment of the specific disease in question is by an 'appropriate antibiotic'.
My request, particularly for the most common ailments, is a further small sentence giving the antibiotic's name. I honestly believe it would do a lot of good to educate sheep farmers and lead to more challenging conversations between vets and farmers and would ultimately improve flock health and welfare. Otherwise, many sheep farmers go on believing that a sick sheep is a dead one.
Andrew Kinsella is a Wicklow sheep farmer and former Teagasc sheep specialist