It worked for our horses’ wild ancestors, but is it wise to co-graze equines and livestock today? Peter Green MRCVS discusses pros and cons
In the UK we tend to keep horses and farm livestock apart from each other. 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. Think of the plains of Africa where antelopes, zebras, elephants, giraffes, rhinos and others all graze and browse. 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 requirement 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.
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.
This is especially useful when mixed grazing is used on marginal land or heathland, but it also has a benefit on lowland grass pastures. Native ponies such as Exmoors are brilliant for conservation grazing, and their impact is increased when combined with cattle.
When it comes to external parasites, there may be both positive and negative impacts when livestock and horses graze together.
If the farm animals, especially sheep, are not treated for ticks, a horse’s exposure to these pests may be increased and the risks of tick-borne infections like Lyme disease may therefore go up. The same may be true for tabanids (horse flies), which are more prevalent around cattle and may therefore bite both horses (and people) in the vicinity. However, if the cattle are treated with fly repellents as part of routine farm husbandry, the horses will benefit from the herd effect of the repellents.
Fungal skin infections such as ringworm are common in housed cattle, especially youngstock, and horses can be infected if they are turned out with them in the spring. The fungal spores are passed from one to another when the cattle rub on gateposts, water troughs and trees. Yet ringworm is not a serious problem and is usually self-limiting, especially in the open air with exposure to sunlight.
Owners are sometimes afraid that their horses will contract sarcoid skin tumours from cattle, because it is known that sarcoids are caused by the bovine papilloma virus. Flies have been proposed as a vector that spreads sarcoids from cattle to horses. In fact, this has not been established.
Bovine papilloma virus is very common in the rural environment and we now know that there is a strong genetic susceptibility in horses to developing sarcoids. Grazing with cattle does not appear to increase the risk.
Another factor to consider is the pasture fencing. Cattle are almost always fenced in with wire stock fencing and barbed wire; their thick skin requires some hefty barriers, or they may push through them. Large-aperture wire stock fencing and barbed wire, especially, can be hazardous to horses, as equine vets will testify.
On balance, however, and with good management, the mixed grazing of cattle or sheep and horses can benefit both the animals and the pasture.
Horses will usually tolerate cattle and sheep, but most seem to hate pigs.
There is much discussion about the reasons for the widespread aversion to pigs, but no solid scientific explanation based on reliable research. Is it the smell, the behaviour or the noises that pigs make? Is there a deep-seated inherited dread of pigs that goes back to those pre-Ice Age times when horses, bison and deer were roaming together and lived in fear of aggressive wild boar? Who knows?
Some horses will freak out on first meeting donkeys, llamas and alpacas. With a patient approach, however, these animals can learn to become grazing companions.
Ref: Horse & Hound; 17 December 2020
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