Susan C. Eades, DVM, PhD, DACVIM
Do you know what is the best feeding program for your horse? What
about supplements? Here are some guidelines to help you avoid feed-related
illnesses in your horse and to feed him to maximize his performance and
There are no strict rules to feeding horses, but one principle is
good to follow: keep it simple. The horse’s digestive system is designed to
live on one of the world’s simplest diets: grass forages. The horse evolved
on grass plains, roaming wide and far at will, and grazing for 18 to 20
hours a day. Today’s domesticated horse doesn’t usually live this lifestyle,
but is stabled and asked to be a companion and an athlete. By keeping in
mind the natural diet of horses and the new demands placed upon them, you
can achieve a balanced diet that will keep your horse happy and healthy.
Adapted to long hours of eating small amounts of fibrous forages,
the horse has a surprisingly small stomach for the size of the animal. The
stomach only holds 2-4 gallons, and does little of the actual digestion.
Horses can neither vomit nor burp. Food passes from the stomach into the
small intestine in about 30 minutes. The small intestine holds 10-12
gallons, and is approximately 70 feet long. From there feed travels to the
cecum, a large, 7-9 gallon, blind-ended compartment, where fermentation of
the ingesta begins. From the cecum it passes to the largest part of the digestive
system, the large colon, holding about 20-25 gallons. Here fermentation continues,
and microbes (bacteria and protozoa) do the bulk of the digestive work.
These microbes convert fibrous feeds into nutrients your horse can use, and are essential
to his health. The microbes can be killed by some kinds of antibiotics or
rapid changes in diet, leading to colic and other digestive problems, so
always consult your veterinarian before making changes in your horse’s diet
or giving medication. Feeding a diet with a high grain content leads to
fewer of these “good” microbes, and promotes growth of microbes that cause
intestinal disease. From the large colon digesta goes to the small colon
where water is absorbed and fecal balls are formed. From there it goes into
the stall for you to clean up. This entire process takes 36 to 72 hours.
The important parts of your horse’s diet are fat, protein, energy
(carbohydrates), vitamins and minerals, fiber, and of course, plenty of
fresh water. Depending on your horse’s level of activity, and stage of life,
the amount of these nutrients necessary may vary. In general, the
requirements are: fat 8-12%, protein 8-14%, carbohydrate 30%, and fiber 50%.
Horses should also drink 6 to 8 gallons of water per day for a 1000 pound
horse. For idle horses or pleasure horses under light work, all of these
requirements can be met by good quality pasture and hay. Horses under
moderate to had work, young growing horses, and brood mares in the last
trimester or lactating may need supplementation with grain or pellets. Here
are some good rules of thumb for feeding horses:
Horses should consume 1.5 to 3.0% of their body weight per day. At
least 50%, probably more, of caloric requirements (80% of feed by weight of
feed) of this should come from forages (grass and hay).
Ample turn-out and grazing time is important and will help keep
your horse from getting bored, and his digestive system working as nature
intended, however, if pasture is limited or unavailable, you can minimize
the effects by feeding several small meals per day. Stabled horses should
never be fed only one meal, but two works well for most horses. Three meals
a day is better for horses under strenuous work such as endurance riding and
Don’t ride your horse right after he finishes eating. Give him at
least an hour after a big meal. Also don’t feed him right after riding. Give
him at least half an hour, longer if he is still hot. It is okay to ride a
horse that has been eating hay or out on pasture.
Observe your horse’s eating habits. Does he always finish everything? Does he
take a long time chewing? This way you can notice problems early. Here are some
signs of problems to watch out for—a normally good eater eating slowly, or picking
at his food can be an early sign of colic. A horse that dribbles grain or drops balls
of chewed hay (called “quidding”) can be a sign of dental problems. A horse that
coughs and looks anxious after eating may be choked. A horse on lush green pasture standing
with front feet outstretched and looking uncomfortable may be foundering.
Good quality pasture should be of a forage grass such as ryegrass or bermuda
grass, and relatively free of weeds. You can keep weed growth down by
Good hay should be green, not yellow or brown, and it should smell
sweet and fresh, not musty or moldy. Different kinds of hay include the
legumes, such as alfalfa and clover, and the grass hays, such as bermuda
grass or timothy. In general the legumes are higher in vitamins and protein,
and are more expensive than the grass hays. Horses should eat at least 1
pound of hay per 100 pounds of body weight (1% of body weight) for good
digestive health. Intake will vary with quality of hay, so a horse eating
poor hay will not eat enough of it to fulfill his requirements.
Feed hay before grain to take the edge of your horse’s appetite, so
that he won’t bolt his feed. Feed bolting can lead to choke and gas colic.
Greedy eaters can also be slowed down by placing large stones (not pebbles)
in the feed bucket.
Making your own grain mixtures is unnecessary. There are excellent
premixes available that have been balanced for all the important nutrients.
Making your own grain mixes or supplementing balanced diets may take the
“balance” out of the ration. You also may consider feeding a pelleted diet.
Although not as tempting as sweetfeed, pellets are convenient and
digestible, and picky eaters can’t sort out their favorite parts. Be careful
though: there are very few pelletted feeds that are high enough in fiber to
be complete feeds. Some horses become chronically colicky or get diarrhea
when on a purely pelletted ration with no hay.
Most commercially formulated grain mixtures and pelleted feeds are
well balanced for nutrients, vitamins and minerals, so supplementing is
unnecessary, but always feed a high-quality, well-known brand. You get what
you pay for. Vitamin supplements may be necessary if your horse has
decreased feed intake due to illness or old age.
Even high quality feedstuffs do not supply the necessary amount of
salt in your horse’s diet. Horses need at least 0.25% of their diet in salt
and most feeds only provide 0.1%. Supplement this by giving your horse a
free choice salt block. High heat and exercise will increase his need for
For horses expected to be athletes, old horses, or horses that have
been ill, you may want to add fat to the diet. Fat is a good way to add
extra energy without extra bulk, and can be done by top dressing feed with
1/4 to 1/2 cup of corn oil per meal.
Keep grain feeding to a minimum. Horses that do not work much do
not need grain at all if fed good quality forages. Ponies need very little
grain even if they are working, as they have a tendency to obesity and
founder. Even working horses should only be fed enough grain to keep them
sleek and energetic. 1 to 2 quarts per meal should be enough for most
moderate working horses. Brood mares and high performance horses may need
more, ideally divided into 3 or more meals a day. If your horse loses
condition or energy, you may need to increase his feed, but consult your
veterinarian to rule out other health problems. Weight loss can be a sign of
systemic illness or parasites.
Good quality forages, hay and commercially formulated grain
mixtures or pellets are balanced in vitamins and minerals, so these do not
need to be supplemented unless horses are on high grain diets or poor
pasture, despite what the supplement ads tell you. Moderate amounts of
healthy treats such as apples and carrots are a good source of vitamins,
There are a few things you might consider supplementing: biotin
supplements can help promote healthy hoof growth in horses with slow growth
or cracks. Glucosamine and chondroitin can help horses with early signs of
You may have heard about the importance of selenium in horses’
diets. Louisiana soils have sufficient selenium to keep your horse healthy.
Even in areas deficient in selenium, such as the Northwest or Northeast, be
careful! Never supplement selenium without consulting your veterinarian,
because it can be toxic.
Another thing you may have heard of is the importance of calcium
and phosphorus. The ratio of these two minerals to each other is important
as well as the amount. In general, horses consuming mixed pasture and hay,
or pasture, hay and grain have diets balanced for calcium and phosphorus.
Horses should be given hay when not out on pasture if they have less than 12
hours a day of pasture access. Hay is higher in calcium than phosphorus, and
grain is higher in phosphorus than calcium. Horses on high grain diets may
need calcium supplementation. Alfalfa is a good source of calcium.
If your horses spend a lot of time outdoors in hot humid weather,
or are asked to exert themselves heavily, especially in hot weather,
consider adding an electrolyte mixture to meals to replace minerals lost in
Fiber is an extremely important, often overlooked part of the diet.
Besides being essential for holding water in the digestive tract and aiding
digestion, fibrous feed such as hay that require chewing keep your horse
from becoming bored and chewing wood or acquiring other vices. The added
salivation from chewing also aids digestion.
Speaking of chewing—have you had your horse’s teeth checked
lately? Uneven wear can cause sharp points that interfere with chewing,
causing weight loss due to insufficient intake or poor digestion. Old horses
may also have cracked or loose teeth. Get your veterinarian to check your
horse’s teeth at least once a year. Horses younger than five or older than
twenty may need teeth checked more frequently.
Horses need access to fresh clean water at all times. Lack of water
can cause dehydration or impactions. Water consumption can be a problem when
horses are stressed or traveling to shows. They may be reluctant to drink
strange water that tastes different or is in a different bucket. Adding a
few teaspoons of kool-aid to the water at home for a few weeks before shows
and then adding it to the water at shows may help disguise the taste of
unfamiliar water if you have a horse that is picky about drinking.
It is impossible to cover every aspect of equine nutrition here, but these
are some of the important points to get you started. Your veterinarian can
help you design a feeding program that is right for your horses, and provide
important information about dietary-related illnesses such as obesity,
founder, ulcers, colic, and orthopedic disease. There are also good books
available on equine nutrition—ask your veterinarian to recommend one.