RED DEER – A horse may be led to pasture but it can’t be forced to eat only what is good for it.
Horses eat a variety of forages and grains with sometimes serious results if moulds or fungus are present, said equine nutritionist Bob Coleman of the University of Kentucky.
“We need to do the best we can to select quality feeds and store them properly so they don’t spoil,” he told a horse breeders and owners conference in Red Deer Jan. 8.
While testing for serious toxins is expensive, horse owners generally pick high quality feeds to avoid problems.
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“By and large the feeds we have available to our horses are safe. People do a good job of selecting quality feeds,” he said.
Mouldy hay or grain produces spores resulting in respiratory problems like heaves, also called recurrent airway obstruction, with symptoms similar to an asthma attack in people. This is a permanent problem for a horse, so prevention is the key.
If the moisture level in hay is 16.5 percent or higher, the risk of mould forming is greater. If mould is suspected, some spores can be removed by shaking or washing the hay.
Moulds produce mycotoxins with the three most common type of spoilage being aspergillus, fusarium and penicillum.
Fusarium is most common and is found in grains and forages. It produces vomitoxin and can causing vomiting.
“We didn’t used to think of forages as a host for fusarium,” said Coleman.
The mycotoxin affects an animal’s metabolism and the digestive tract, leading to diarrhea or colic. It can lead to respiratory ailments and a suppressed immune system.
Certain pasture grasses and legumes can create serious problems for horses so it is wise to identify different varieties.
Tall fescue is a perennial cool grass that can produce an endophyte or fungus that increases plant vigour. However, the endophytes also produce ergot alkaloids that are particularly harmful to pregnant mares.
Although other classes of horse tolerate it, pregnant mares should be removed from tall fescue pastures 60-90 days before foaling.
The ergot problem may cause the mare to have difficulty giving birth. The placenta may be thickened and the foal has trouble breaking through. The foal may be malformed and the mare may not produce milk.
Perennial rye grass may also contain an endophyte that leads to neurological problems in all classes of horses. Horses stagger and appear unco-ordinated. They recover if they are removed from this grass.
Alsike clover can produce a toxin during periods of higher rainfall or humidity that cause lush growth. It produces a pink and white flower. It causes severe photosensitivity during which skin sloughs off. Liver damage is another symptom. It should not be included in pasture mixes for horses.
Red clover may develop mould during periods of high humidity. The mould causes excess slobbering and removing horses from red clover fields results in a quick recovery.
