Why “roughs” in pastures are good for horses


Who doesn’t love a nicely manicured paddock? But if we don’t have areas of “rough” among the “lawns”, our horses are at risk of higher parasite exposure.

Parasitologist Martin Nielsen explains that horses have a natural defence mechanism against parasites, in that they will graze away from the “roughs” in their paddock, where there is manure.

Those rough areas have a higher infection pressure with parasitic larvae in the grass.

“If we overgraze and overstock a given pasture, all of a sudden you will no longer see those roughs because horses will be forced to graze closer and closer to the defecation areas,” Nielsen says.

“Those horses are exposed to 10 to 20 times as many larvae per kilo of grass, as opposed to just grazing ‘the lawns’.”

And if you want to break those areas up by mowing or grazing to help reduce parasite exposure, then ideally, conditions need to be dry for about four weeks and the temperature needs to be at least 30 degrees Celcius.

Neilsen says that parasites love moderate temperatures and rain, so if conditions are not ideal “the only thing you will have accomplished with or mowing or harrowing is to spread out the larvae more and expose the horses more to those larvae. It might take up to a year for all those larvae to completely disappear.”

Got something to say about this? You can comment below.

» Next: Daily dewormers ineffective in horse parasite resistance battle

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Visit Martin Nielsen’s Network for Good page, and his University of Kentucky page.

2 thoughts on “Why “roughs” in pastures are good for horses

  • November 25, 2019 at 3:21 pm

    What about if you harrow, or top and harrow and then graze with cattle, sheep or goats before the horses go back in?

    • December 4, 2019 at 1:08 am

      Yes, if you graze with ruminants, you will very likely get a significant reduction of parasite loads on pasture. But the effect will depend how effectively they graze the pasture down. And then the pasture will need a little time to recover and grow back up afterwards.


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