- Always feed horses clean, unmoldy forages. Horses are extremely
susceptible to molds, fungi, and other toxic substances in forage.
Mold problems generally occur in hay that has been baled at too
high a moisture level (20 percent or more) without the use of
a preservative. This is especially a problem with first-cut hay,
because it is harvested at a time when rain is frequent and weather
conditions are not optimal for hay drying.
- Do not feed horses sudangrass or sorghum-sudangrass hybrids.
Sudangrass and sorghum-sudangrass hybrids contain compounds that
can cause muscle weakness, urinary problems, and, in severe cases,
- Do not feed mares tall fescue containing an endophyte fungus.
Older varieties of tall fescue may contain an endophyte fungus
that can cause severe health problems when eaten in summer. Mares
are especially sensitive to the fungus. During the last three
months of gestation, mares should be removed from pastures containing
endophyte-infected tall fescue. Tall fescue varieties that are
free of the endophyte fungus are now available.
- Do not feed horses hay containing blister beetles.
The beetles irritate the lining of the horse’s digestive
tract, usually causing death. The beetles are most likely to be
found in alfalfa hay produced in southern areas of the United
States. Purchase hay that is guaranteed to be free of blister
- Identify and remove poisonous plants from pastures. Poisonous
plants in pastures or hay can be fatal to horses. Ornamental shrubs
and nightshade are the most common poisonous plants in Pennsylvania,
but any plant that is known to be poisonous to other animals is
probably poisonous to horses. Fortunately, many poisonous plants
are not palatable, and horses will not eat them if forage is
adequate to meet their needs.