| Animal Health
Parasite threat to sheep and cattle at turnout
NADIS March Parasite Forecast .
U nseasonably high winter temperatures across most parts of the country could impact on parasite infectivity at turnout for both sheep and cattle , according to NADIS in its March parasite forecast . Merial Animal Health , sponsor of the forecast , recommends that farmers plan their parasite control now for this year ’ s grazing season , to reduce production loss .
In sheep , this winter ’ s higher than average temperatures indicate a moderate to high risk of chronic liver fluke disease in parts of the UK . Scotland , North Wales and North West England are predicted to experience the highest incidences of disease . “ Treating ewes to remove patent , egg-shedding liver fluke infections will help to reduce subsequent fluke challenge to growing lambs later in the year ,” advises Merial ’ s veterinary advisor Sioned Timothy .
“ As chronic fluke disease is caused by the adult stage of the liver fluke it is not necessary to use a triclabendazole-based product that targets all stages of the parasite at this time of year . Alternative flukicides that target the more mature life stages of the parasite such as , nitroxynil ( Trodax ®), closantel , albendazole or oxyclozanide may be more appropriate at this time of year . Once treated , sheep should be moved to clean pastures .”
20 | Farming Monthly | March 2017
The principle aim of parasite control at lambing is to minimise pasture contamination with eggs passed from adult parasites . The likelihood of lambs and ewes becoming infected when grazing can be determined by the previous use of pastures .
Maximising the use of ‘ safe grazing ’ ( i . e . pastures that have not been grazed by sheep in the last year or re-seeded pastures ) at turnout will help avoid the risk of nematodirosis and parasitic gastroenteritis ( PGE ) in lambs later in the season . If safe grazing is not available for the whole flock it should be reserved for higher-risk ewes and those rearing multiple lambs .
Dosing ewes around lambing time can help reduce the ‘ periparturient rise ’ in faecal egg production during the grazing season , which can cause PGE and production loss in lambs later in the year . However , any decision to treat ewes during or after lambing must take wormer effectiveness , and the timing and frequency of dosing into consideration , to avoid increasing anthelmintic resistance .
SCOPS advises adopting a compromise between reducing pasture contamination and achieving full parasite control by targeting youngstock , ewes rearing multiple lambs , and ewes in a low body condition , leaving around 10 % of the overall flock untreated . This approach will protect overall production and reduce overall egg output onto pastures , while preventing selection for anthelmintic resistance .
Nematodirosis can cause considerable production loss at turnout . Cold weather delays the hatching of the Nematodirus battus eggs on pasture , but sudden increases in temperature can trigger a mass hatch . If hatching coincides with lambs taking in significant quantities of grass , infection rates and resulting disease can be high .
From March onwards both NADIS and SCOPS provide Nematodirus forecasts that alert farmers to the risk of egg hatching in their local area . Using these resources alongside a strategic plan for safe-grazing and targeted treatments can lessen the impact from nematodirosis . It is important to reduce pasture contamination wherever possible , to reduce the risk of infection in the following season .
Coccidiosis may also occur in young lambs and can present with similar clinical signs to nematodirosis . Stress is a major factor in triggering outbreaks , but adverse weather conditions , poor colostrum supply , wet , muddy paddocks previously grazed by sheep , and / or extended housing periods may also predispose lambs to infection . A vet should be consulted if differentiation between nematodirosis and coccidiosis is required .
Cattle farmers are urged to plan their parasite control for the year and decide on a strategic or targeted approach . Strategic parasite control plans use timed dosing and grazing management techniques , whereas targeted approaches monitor animals regularly and treat when necessary .
COWS recommends considering the production objective for the types of cattle present , the farm infrastructure ( particularly in relation to pastures , grazing management and handling facilities ) and the presence of existing parasites when planning a control strategy for the season .
Housed youngstock , which were not dosed for worms in the autumn , may be at risk from type 2I ostertagiosis caused by inhibited ( L4 ) gutworm larvae towards the end of the housing period . Animals assessed as being at risk should be treated with a product that removes L4 stage Ostertagia ostertagi .
“ After turnout , young cattle rapidly become infected from overwintered larvae on the pasture ,” says Ms Timothy . “ Strategically treating youngstock at grass can help prevent parasite burdens from increasing and avoid high levels of pasture contamination later in the grazing season . This lessens the risk of parasitic disease and can protect growth rates and overall production .
“ Cattle can be treated with an appropriate
www
. farmingmonthly . co . uk