Friend or foe?

It worked for our horses’ wild ancestors, but is it wise to co-graze equines and livestock today? Peter Green MRCVS discusses the pros and cons

- Peter Green

IN the UK we tend to keep horses and farm livestock apart. Horses belonging to farmers may be turned out with the cattle or sheep, but, on the whole, equines are managed separately. Of course, this is artificial. In pre-Ice Age Britain, wild horses grazed with bison, deer, woolly rhinos and wild cattle called aurochs.

There are pros and cons to modern mixed grazing. The big winner when you turn cattle and horses out together is worm control. Because cattle don’t support the same nematode worms as horses but will ingest their eggs as they graze, worm burdens in horses grazed with cattle are lower and the need for wormers is reduced.

In one recent study in France, young horses grazed with cattle had 50% fewer worm eggs in their droppings than those grazed alone. And it works both ways, because the cattle also have fewer worms.

There is a risk of liver fluke infection if horses graze on marshy, marginal pastures where the snail that carries the parasite thrives. Most farmers know that they should treat sheep or cattle on such pasture for fluke, but treating horses is rarely necessary.

Another plus is the pasture itself. Horses have incisor teeth in both upper and lower jaws, while cattle and sheep only have lower incisors. They graze in different ways and have different preferences. Horses tend to be more picky and will overgraze some patches and leave others, while both cattle and sheep are less discriminating.