Parasitic gastroenteritis is the main production limiting disease of sheep in the UK, with an annual cost to the UK industry of about £84 million.
This is because stomach worm infections can decrease growth rates in lambs by as much as 47 per cent and wool production by up to 21 per cent.
Traditionally, farmers have routinely wormed ewes and lambs to protect them from worms. However, the rise in anthelmintic resistance and changing weather patterns mean farmers are having to take a more informed approach to manage parasites on their farm.
Farmers can keep an eye on parasite issues from across the country through the Parasite Watch, a scheme run by Zoetis, which uses a network of 26 farms who are monitoring worms, fluke and flies.
In this first update, we meet two of the farms involved in Parasite Watch to find out how they are managing parasites ahead of the main season.
Details on www.parasitewatch.co.uk
John and Sarah Yeomans, Llwyn y Brain, Newtown, have been taking a strategic approach to parasite control on their 110ha (272 acre) farm for more than a decade. They say in the last 20 years the parasite situation has changed with fluke an increasing concern.
They have five strands to their parasite control which include:
1. Not worming every ewe and lamb. Some of the ewes are treated prior to lambing leaving at least 10-20 per cent of the young, fitter and single-bearing ewes untreated. By not worming every animal they contribute to the number of worms not exposed to treatment which should help to slow the development of resistance on farm.
2. Only worming under-performing lambs. Lambs are wormed based on their growth rate. After weaning, lambs are weighed every three to four weeks with underperforming lambs not showing other health issues wormed if needed.
3. Using faecal egg count tests to monitor worm burdens and copro-antigen tests to monitor fluke.
4. Mix grazing cattle and sheep to clean up pasture.
5. Having a closed flock and herd with a strict quarantine period.
The couple start lambing their flock of 700 ewes on 20 March with the flock heading to the hill in the middle of May. Prior to this all of the lambs are weighed, and again at weaning in July/ August and then every three to four weeks onwards until they are sold. Anything with an unacceptable growth rate is shed-off to one side and treated with a wormer.
Mr Yeomans says: “If the lambs are not lame and they have not got a trace element deficiency then we know there is a high probability their reduced growth rate is as a result of stomach worms. Sarah is in charge of weighing and the weigh head sends the weight to my phone via bluetooth. My phone then speaks out their weight so we do not even need to look at the screen.
“We also take faecal egg count (FEC) tests as part of Parasite Watch and that is a good warning sign too, coupled with any drop-in growth rate,” he adds.
Mr Yeomans says the changing weather patterns and the fact the farm is heavily stocked means they have had to start worming some lambs on the hill.
He adds: “This is where faecal egg counts are helpful in alerting us early to any possible worm issues.”
Mr Yeomans says the parasite risk has changed on his farm over the past 10-20 years with nematodirus often seen in the autumn as well as the traditional spring. Fluke has also become an issue where 20 years ago there was none.
Sheep are mainly grazed on a 24-day rotation and they are also mixed grazed with the cattle until weaning.
Both the flock and herd are closed, which Mr Yeomans believes is vital to the health of his stock. He has also double-fenced a lot of his land to maintain a fully closed flock.
Mr Yeomans took his first FEC sample in April.
· 700 ewes and ewe lambs- mostly Beulah and Beulah crosses
· 70-75 cow Limousin cross suckler herd
· 110ha (272 acres) - 53ha (131 acres) of which is improved hill land.
Livestock farmer Tom Carlisle has been monitoring worms using faecal egg count tests as part of the Zoetis Parasite Watch Scheme for the past three years. Prior to this he, like many others, would routinely worm lambs with a white wormer, followed by a clear wormer every month throughout the grazing season.
However, since being involved in Parasite Watch he has had his eyes opened to the fact lambs often do not need worming, which he says has saved him £1,000s of pounds in medicine and labour as well as helping preserve the wormers he uses on the farm.
Mr Carlisle takes FEC samples from three parts of the farm where the sheep are grazing which builds a picture as to whether all lambs or just some grazing certain pasture need treating. Any egg counts coming back higher than the treatment threshold of 250 eggs per gram (EPG) are treated. The wormer he selects is always done in consultation with his health care provider.
Mr Carlisle says regularly taking FEC samples every two to three weeks has often alerted him to problems before any clinical signs.
He says: “Quite often we do not see clinical signs but the egg counts have shown us otherwise. If you wait until you have clinical signs and the lambs are going mucky and they are nicked in at the belly you have lost growth and it can take them over a month to get back on track.
“We have been really surprised how there is really no need to dose every month and this has saved us hundreds of pounds every year. Taking an egg count sample has also shown us how random it can be and you may expect a high egg count because it has been wet, but it comes back low.”
Zoetis vet Ally Anderson offers some top tips on managing parasites this spring.
She says protecting stock against parasites at the correct time and with the correct product at the correct dose rate is vital for effective control and to help prevent resistance from developing within your flock.
"The use of monitoring tools is important so you know which parasites are an issue, what products to use and when to use them."
Tools available include: