Composting an effective parasite-control tool – study

Parascaris equorum
Large roundworm – Parascaris equorum

Picking up and composting horse manure is an effective way of destroying the eggs of a troublesome parasites in horses, research has shown.

The large roundworm of horses, Parascaris equorum, is found throughout the world.

It is a common parasite of foals. Adult worms live in the small intestine. They may grow up to 50cm in length. A heavy infection leads to failure to thrive, and may cause intestinal impaction or rupture.

Deaths have been reported in foals up to 4 months of age.

P. equorum produces vast numbers of eggs. A single female may produce over 200,000 eggs a day. Under optimum conditions, they become infective within about two weeks of being passed in the faeces.

The eggs are particularly resistant to extremes of climate and may survive for many years in stables and on pasture. Composting is becoming a popular method of dealing with waste from equine premises.

A study has carried out by researchers from the University of Kentucky Department of Animal and Food Sciences on a central Kentucky horse farm to determine whether Parascaris equorum eggs survive in composted manure.

The researchers studied the viability of the eggs in manure subjected to windrow composting.

For the study, a single windrow about 42.3 metres long, 2.7 metres wide, and 0.9 metres high was built.

It contained equine manure, soiled bedding and other waste material, which came from stables occupied by adult stallions and mares.

Temperature and carbon dioxide levels within the row were monitored daily. The compost was mechanically turned and aerated as necessary to maintain optimum conditions. Previous experience had shown that it took 10-12 weeks for the windrow to decompose completely.

Sentinel chambers were used to expose 3-gram samples of dung to the composting process. The faeces, collected from a weanling foal, had an average of 2216 P. equorum eggs per gram.

The chambers were made of mesh that kept the P. equorum eggs inside, whilst allowing liquids and bacteria to pass through.

Chambers were exposed to one of three treatments.

Constant exposure: These were placed within the centre of the windrow. Each day after the windrow had been turned, the chamber was placed back in the centre of the windrow.

Intermittent exposure: The chambers were placed in the centre of the windrow. On alternate days, after the windrow had been turned, the chamber was placed back in the centre, or placed on the outside of the windrow.

Control chambers were kept at 4 degress Celsius.

Every two days, one chamber from each group was removed and incubated at room temperature for 21 days, at which stage the eggs were examined microscopically to assess if they were viable. (Viable eggs contained larvae.)

Chambers treated with constant exposure contained about 10 per cent viable eggs on day 2 and 0 per cent by day 8. Intermittent treatment resulted in 16 per cent viable eggs on day 2 and 0 per cent by day 6. In contrast, control chambers had average P. equorum egg viabilities of 79 per cent throughout the 18 days of the study.

The researchers concluded that not only was the windrow composting system effective in eliminating viable P. equorum eggs, it did so rapidly.


» Horse manure – an easy guide to composting


The effects of windrow composting on the viability of Parascaris equorum eggs.
Gould JC, Rossano MG, Lawrence LM, Burk SV, Ennis RB, Lyons ET.
Vet Parasitol. 2013 Jan 16;191(1-2):73-80.
doi: 10.1016/j.vetpar.2012.08.017.

Equine Science Update




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