Parasite Paradise

New Zealand is a fabulous place to live. Most of us here think so. Unfortunately, intestinal parasites of horses seem to completely agree! Our climate is very favourable for the lifecycles of intestinal parasites – and without making it all seem overly complicated, I thought I would give a brief rundown of the do’s and don’ts of pasture management in horses in NZ. 

The first “don’t” is the commonly held belief amongst our horsey community that harrowing is good.  Let me elaborate. Harrowing is good for our soil and therefore our pasture – no argument there. All soil benefits from the addition of organic matter, which horse-pooh is. However, in terms of parasite control, it is the single WORST thing you can do! In England, harrowing is common practice – but in England, the weather is horrid for a large portion of the year – they get many days of frosts and snow. And in these conditions, harrowing will indeed mean the parasite larvae within the pooh get killed. But here near Auckland, how many frosts do we get a year? Usually, less than we can count on one hand. How many days with 30-degree heat? Also, less than we can count on one hand.  So that’s 10 days of the year where harrowing *might* kill parasite larvae and 355 days where it won’t.  So harrowing is then simply spreading your parasites over your ENTIRE pasture, rather than in the small zone surrounding each pooh.

You all know how in an un-harrowed pasture, there will be areas of “roughs” where the horses pooh and don’t graze, and smooth short “lawns” where they graze and don’t pooh? That is the result of thousands of years of evolution of our horses telling them to keep their bathrooms separate from their kitchens! And if you harrow, you are simply spreading their bathrooms all over their kitchens.  Ew right?

So what should we do? Best thing: pick the pooh up. At least twice weekly in summer and once weekly in winter. Too lazy or short on time? Leave the pooh where it is and ignore the roughs, or ideally cross-graze with adult sheep or cattle who will vacuum up those larvae for you and tidy the long bits up (please note, younger sheep or cattle, or alpacas/llamas/goats of any age will NOT be effective at cross-grazing).

Are you after the holy grail of both parasite control and soil/pasture health? Then the answer is to pick up the pooh, and compost it using enough moisture and fibrous matter (leaves/tree prunings/old hay/straw/stable shavings) so that time and temperature kill the larvae, then spread back onto your pasture. You are allowed to use your harrows for that part! Happy pooh-picking!

Tanya Grey BVSc – Equine Veterinarian