News
Staff Member
The April Parasite Forecast webinar has now been updated
We are pausing the Disease Alert webinar until the autumn and replacing it with a Blowfly Alert.
Parasite Forecast - April 2018
February started off cold, becoming less cold in the middle of the month, but with snow towards the end of the month. Maximum and minimum temperatures were between 1.0 and 1.5 °C below average in most areas, with the UK mean monthly temperature 2.4 °C. which was 1.3 °C below than the 30-yr long-term average. Rainfall was 73% of average, and a few places had less than half the average rainfall total for the month, with only a few areas near or above average.
April Parasite Forecast/Update
SHEEP
Worming ewes at lambing time
With lambing now well under way, attention will be focusing on controlling parasite burdens in ewes.
The principle aim of worming ewes at lambing time is to minimise future pasture contamination with worm eggs during the 'peri-parturient rise" (PPR).
Eggs passed out in the faeces of infected ewes hatch and develop into infective larvae under favourable conditions, which can then lead to disease in lambs later in the season as larval numbers build up on the herbage.
Worm faecal egg output is much reduced in well fed ewes in good condition.
Provision of 'safe grazing' for ewes and lambs available at turnout will also help avoid the risk of worm infections in lambs later in the season.
- 'Safe' pastures should not have been grazed by lambs the previous year and include fields grazed by cattle last year; and re-seeded pastures.
As wormer resistance is becoming more common, advice on worming ewes is changing, influencing both the choice and frequency of ewe treatment pre- and post-lambing.
The timing and choice of wormer are both important in controlling the PPR, as the ewes can quickly become re-infected, particularly when grazing heavily infected pastures post-turnout.
Current worming advice recommends leaving a proportion of the ewes untreated by targeting treatments to include;
- Gimmers and young ewes
- Ewes nursing twins and triplets
- Ewes in low body condition
Persistent, or long-acting wormers, which provide a prolonged period of protection, if given later in the lactation period, before ewes become re-infected from the in refugia population, can be highly selective for resistance.
Worms in refugia include the population of worms present in untreated sheep and the free-living population of eggs and larvae not exposed to wormers.
The recommendation for long-acting formulations of moxidectin, is to use these products prior to lambing, or at turnout.
Further details can be found on the SCOPS website at www.scops.org.uk.
Ewe worming treatments should aim to reduce pasture contamination during the periparturient rise whilst at the same time not selecting for anthelmintic-resistant strains of parasites.
Some ewes nursing singles could be left untreated; seek veterinary advice for your farm.
Nematodirosis
Severe outbreaks of nematodirosis can occur in 6 to 12-week-old lambs usually from April to June in some years, depending on prevailing weather conditions.
Cold late springs followed by sudden changes in temperature can trigger a mass synchronised hatch of infective larvae leading to severe production losses and even death in lambs grazing contaminated pastures.
As February has been cold, and weather conditions during March and April can significantly alter early season predictions of nematodirosis for flocks lambing during March/April, an updated disease risk will be included with the NADIS May parasite forecast.
Prediction of Nematodirus Peak Hatch weeks. To learn more about the full Nematodirus alert, click here
Disease outbreaks can be prevented by grazing lambs on pasture not grazed by lambs the previous year ('safe pasture').
Where this is not possible, and local weather conditions are such that an early hatch occurs, then late January/February-born lambs may need prophylactic anthelmintic drenching.
March/April-born lambs may require prophylactic anthelmintic drenching in May if cold weather prevails during March/April and hatching is delayed.
Continue to monitor the SCOPS ( www.cattleparasites.org.uk) website.