Pasture Management – The Facts


Pasture management plays a key role in worm control and is as important as the active worming programme that you have.

Every time your horse takes a mouthful of grass he could be eating worm larvae with it.

The life cycle of the worm means that it spends a large proportion of its life outside of the horse in the grass.  If this part of its life cycle is interrupted then it cannot survive.

Dung collecting is the most important thing that you can do to stop the worm’s life cycle.  The eggs are passed out in the horse’s dung and then hatch into larvae.  The larvae move into the grass, climb up the grass stalk and are eaten by the horse.  If the dung is removed then the eggs do not have a chance to hatch and the worm life cycle is over.  One pile of dung could contain 10,000’s eggs.  The recommended frequency for dung collecting is at least twice weekly.

There are other key pasture management recommendations:

Do not overstock the pasture.

Horses create natural ‘toilet’ areas in the grass, which are commonly known as ‘roughs’.  These areas have a much higher concentration of worm eggs than the grazing areas known as ‘lawns’.  If you overstock the pasture then the horse is forced to feed from the rough areas and therefore may eat large quantities of worm larvae.  Ideally no more than one to two horses per acre.

Rest pasture for a minimum of  three / six months

If pasture is rested then the worm life cycle is over.  The larvae are not ingested and die.  It is worth noting than some larvae can last for long periods in the grass and a frost is required to kill them.

Graze the land with other animals (Sheep / Cows / Goats)

These animals act as ‘vacuum cleaners’ on the pasture, as they eat the grass with the worm larvae on it.  The larvae cannot survive in these animals and die.  This is much more effective than simply resting the pasture.

Harrowing?
Harrowing in spring, autumn and winter simply spreads the worm eggs around the field, making it more likely that your horse will eat larvae and is a bad idea, unless sheep or cows are moving onto the land.  Harrowing in the summer during a hot period should ensure that the sun kills the worm larvae, and is a good idea.

Graze young and old horses separately

Young horses are more susceptible to worms and should graze in separate pasture to their older companions.  The same is sometimes true of veteran horses and ponies, as some will also an immune system that reduces with age and will be more susceptible to worm infestations.

Faecal egg count all horses grazing together

Pasture contamination can be identified through us of faecal egg counts.  There are a number of yards on Intelligent Worming Programmes who have ‘dirty’ fields.  We have identified through faecal egg counts that these fields carry large volumes of larvae and the yard needs to take a different worming strategy when horses are grazing on these fields.

Keep grazing herds ‘closed’
If you run a large yard or stud then the groups that you graze the horses in should remain as static as possible.  This will ensure that horses with high worm burdens infect only a small percentage of the horses at the yard / stud.