Merial - Spring temperatures warm up parasite activity in sheep and cattle

Discussion in 'NADIS Animal Health' started by Chris F, Apr 18, 2017.

  1. Chris F

    Chris F Staff Member



    Spring temperatures warm up parasite activity in sheep and cattle

    Harlow, UK – April 18th 2017

    NADIS April Parasite Forecast

    Merial Animal Health’s Veterinary Adviser Sioned Timothy is advising sheep and cattle farmers to implement stringent parasite control strategies this spring, based on forecasts by NADIS of a high risk of parasitic disease following persistent warm temperatures.

    Sheep farmers should consider the impact that parasite burdens in ewes will have on the challenge faced by lambs later in the season. The aim is to minimise pasture contamination with worm egg output during the ‘peri-parturient rise’ (PPR) whilst at the same time minimising selection for anthelmintic-resistant strains of parasites.

    “Managing the threat of wormer resistance should influence treatment strategies at this time of year,” advised Sioned. “Long-acting wormers can be highly selective for resistance if the effects of treatment persist beyond the end of the PPR, thus preventing ewes from re-establishing a worm burden from pasture-based refugia before their parasitic immunity is restored, To counter this, persistent wormers should be used prior to lambing or early in the PPR.”

    Current advice recommends that treatments should target higher risk animals, including gimmers, young ewes, those nursing multiple lambs and ewes in low body condition. The rest should be left untreated unless there is a risk of haemonchosis on the farm.

    Prioritising ‘safe-grazing’ for lambs and ewes at turnout will help to reduce the risk of worm infections in lambs later in the season. ‘Safe’ pastures are those that have not been grazed by lambs in the previous season and can include those previously grazed by cattle and re-seeded pastures. If safe grazing is limited it should be reserved for ewes rearing multiple lambs whilst singles, which are more resilient to parasite infection, graze more contaminated pastures. For further details visit the SCOPS website at or speak to your vet for advice tailored to your farm.

    Depending on prevailing weather conditions, severe outbreaks of nematodirosis can occur in six to 12 week-old lambs from April to June. Control is best achieved by grazing lambs on safe pastures. Where this is not possible, farmers should consult the SCOPS website regularly for disease risk updates in their area to determine whether treatments are necessary to prevent outbreaks.

    Coccidiosis may also be encountered during April in lambs between four and eight weeks of age. The risk of coccidiosis can be influenced by a number of factors including; poor nutrition, wet weather, overcrowding, grazing wet muddy paddocks previously grazed by sheep and/or extended housing periods.

    Reducing stocking densities, batch rearing of lambs, creep feeding and avoiding heavily contaminated pastures can help reduce the likelihood of coccidiosis outbreaks. However, strategic treatment of lambs on contaminated pastures may still be required. Taking the correct action can prevent a serious and costly check in the growth rate of lambs. Farmers should consult their vet or animal health advisor for guidance in their situation.

    Chronic liver fluke in sheep may still be encountered at this time of year and can be confirmed by checking for the presence of fluke eggs in faeces, warns Sioned. “Sheep on premises with known fluke populations or in high-risk areas should have already been dosed in the autumn, but may need to be treated again this spring.

    “Flukicides containing albendazole, closantel, nitroxynil or oxyclozanide are effective at treating adult flukes responsible for chronic disease. Triclabendazole-containing products can then be reserved for treating acute fluke disease later in the year.”

    Sheep should be moved to clean pastures after treatment, and provided with supplementary feed where necessary to maintain condition.

    Cattle turned out to pasture should be clear of parasites, having received any treatments required to remove worms over the housing period. If animals are grazing contaminated pastures this spring, or were not wormed during housing, the risk posed by gutworms and resulting parasitic gastroenteritis (PGE) may be high.

    Yearling cattle not dosed with a wormer effective against the encysted stages of Ostertagia ostertagi in the autumn, and housed over winter, may be at risk from type II ostertagiosis as spring temperatures increase. Signs include sudden onset of severe scouring with loss of appetite and rapid loss of body weight. Although the prevalence of clinical disease is usually low, with only a proportion of animals in a group affected, mortality in affected cattle can be high.

    Now is the time to plan grazing strategies to achieve optimal worm control. PGE can be prevented in growing cattle by annual rotational grazing, ideally rotating cattle, sheep and crops, however on many farms this is not possible.

    Where safe grazing is unavailable, calves born during the previous autumn will almost certainly require worm treatments in their first full grazing season to control PGE. Farmers should put in place a strategic or targeted parasite control plan, depending on the farm history and risk of disease, to protect health, welfare and productivity during the coming grazing season.

    Lungworm should not be overlooked. Vaccination against lungworm must be completed before turnout and in many areas it will now be too late to give adequate protection. In this case, anthelmintic treatments may be required for lungworm control. Farmers should speak to their vet or animal health advisor to determine how best to integrate lungworm control into their parasite control plan for the coming grazing season.

Share This Page