What will be living on your pasture over winter?

By Lucy Hepworth BVSc MRCVS

There has definitely been a lot of cattle lungworm in the Blackmore Vale in late summer/early autumn this year. What does this mean for your pasture if lungworm has been present on your farm this year? Lungworm in sheep is caused by a different species and there are usually no clinical signs, but in heavy infestations it can cause coughing and weight loss.


L3 larvae are excreted by cattle with lungworm onto the pasture. Historically most lungworm larvae tended to die over winter, and the following spring, pastures were contaminated by older carrier animals excreting lungworm larvae. However, as our climate changes, so do parasites and we should be aware of lungworm larvae being able to overwinter. Larval survival will also be influenced by how late in the season they are excreted.

So, if lungworm has been an issue this year on farm, then consider using the lungworm vaccine ahead of turnout next spring to give animals immunity. Alongside using the vaccine, consider the risk of the turnout pasture:

Low lungworm pasture risk doesn’t mean no risk. Cattle lungworm has cleverly adapted to use a fungus as part of its life cycle. The larvae can hitch a lift on the fungal spores and get carried from contaminated pasture to low risk pasture.

For farms who don’t use the vaccine, planning turnout to avoid high risk pasture is even more important. Strip grazing and use of back fencing will help to reduce the chance of a significant build-up of larvae. If high/medium risk pasture needs to be used with first year grazing animals that are not vaccinated, then a strategic worming protocol is likely to be warranted.

Gutworms have also benefitted from a warm wet autumn, and we have seen high worm egg counts in our lab recently. Infected animals excrete eggs onto the pasture which either overwinter if deposited late in the season or hatch out into larvae in a mild autumn. Gutworm larvae are known to overwinter relatively well, especially if the weather is cold because they are less active and retain energy reserves until spring.


So, a similar principle applies to management of pasture for gutworms. Pasture which has been contaminated this autumn should be avoided for turning out naïve animals onto. High risk pasture should be grazed by immune adult animals, or left until June, otherwise a strategic worming control protocol needs to be in place.

Annotating a map of the farm with ‘which fields have been grazed when’ together with a record of any parasite burdens with dates, can be a useful way of deciding which fields present the lowest risk for turnout. Parasite mapping fits well with reducing dependence on wormer products and is part of a wider approach to minimising parasite impacts in sheep and cattle.

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