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Copyright 2005, Board of Trustees, University
4-H HORSE PROGRAM
This educational material has been prepared for 4-H use by the Cooperative Extension Services of the U.S.
Department of Agriculture and State Land-Grant Universities in cooperation with the National 4-H Council and the
American Quarter Horse Association.
Trade or brand names used in the publications are used only for the purpose of educational information. The
information given herein is supplied with the understanding that no discrimination is intended and no endorsement
of products or breeds of horses by the Federal Extension Service or State Cooperative Extension Services is
implied, nor does it imply approval of products or breeds of horses to the exclusion of others which may also be
This material was originally published by the National 4-H Council, 7100 Connecticut Avenue, Chevy Chase,
Programs and educational materials of National 4-H Council are available to all persons regardless of race, color,
sex, age, religion, national origin or handicap. Council is an equal opportunity employer.
Horse Science: Feed Nutrients
You probably feed your 4-H horse a supplement. You
know that the supplement will make your colt grow faster
and be healthier. The horse will be in "better shape" than if
you just let him graze.
You know this because you know something about
animal nutrition. Animals need many different kinds of
nutrients. Different animals need different kinds and
amounts of nutrients. This is where the science of animal
nutrition comes in. Part of the animal nutritionist's job is to
find out what nutrients animals need.
In feeding experiments, different feed ingredients are
tried. In the laboratory, feeds are analyzed. Nutritionists
search for the best combination of feeds for the kind of
horse being fed. For mares nursing foals, the feed must help
produce milk. For a pregnant mare, the feed is designed to
help produce a healthy foal. For a young horse, feed is
designed for growth and development as well as
maintenance and energy.
After experiments are conducted, they are checked and
rechecked. Then the results are used to make
recommendations to horse owners. This means good rations
for a minimum cost to horse owners. It also assures you that
your horse is fed in a way to meet the needs of his body in
the type of work that he is doing.
KIND OF NUTRIENTS
There are many different chemicals in feeds. Animals
need some of them in large amounts others are needed only
in tiny amounts. Some have not been discovered or named
These feed constituents are divided into five main types
of nutrients. Each type has a different job in the animal's
body. The five types are (1) energy nutrients (carbohydrates
and fats), (2) proteins, (3) vitamins, (4) minerals, and (5)
None of these is more important than the others. All are
essential. But with the exception of water, the energy
nutrients usually make up the greatest bulk of feed.
Energy nutrients are the body's fuel. In fact, they are
even chemically similar to fuels we use gasoline, oil and
THE ENERGY NUTRIENTS
After digestion, the energy nutrients are carried by the
blood to the cells of the body. In reactions very much like
burning, they are used by the cells for energy. Energy or fuel
is required to power the movements of muscles walking, a
beating heart, breathing, blinking eyes and contractions of
the digestive system. At the same time, heat is produced to
maintain body warmth.
The main energy nutrient is carbohydrate. There are
many carbohydrates. Even the relatively simple ones are
complex compounds. All carbohydrates are made up of
carbon, hydrogen and oxygen. Carbon is the key to
carbohydrates. This element can behave in several different
ways. As a result, there are thousands of possible
combinations of carbon, hydrogen and oxygen.
Sugars and starches are carbohydrates. They are
relatively simple. Cellulose is one of the more complex
The sugars and starch are easy to digest. They have a
high "feeding value" because very little of them pass
through the body undigested. Grains such as corn and oats
contain much sugar and starch.
Cellulose is chemically a carbohydrate. It makes up the
fiber in plants. Grass has much cellulose. Cellulose is hard
to digest. For most animals it has a low feeding value;
however, ruminants (cattle and sheep) can digest large
amounts of cellulose with the aid of bacteria in the rumen.
The caecum or large intestine of the horse functions similar
to the rumen in cattle and sheep.
Another group of energy nutrients is the fats and oils.
Fats and oils are chemically alike. Their main difference is
that fats are solid at body temperature; oils are liquid. Both
are usually called fats.
Like carbohydrates, fats are made up of carbon,
hydrogen and oxygen. They are also used to provide energy
for movement and heat. Fats contain a higher percentage of
carbon and hydrogen atoms than carbohydrates do. Thus, the
energy in fats is more concentrated. Fat has 2.25 times more
energy per gram than carbohydrate.
GLYCEROL FATTY ACIDS
Horse Science: Feed Nutrients
While carbohydrates and fats supply energy, proteins
supply the material from which body tissue is made. They
are the bricks and mortar from which bodies are built.
Proteins are highly complex. In addition to carbon,
hydrogen and oxygen, they contain nitrogen. Some proteins
also contain sulfur. A few contain phosphorus or iron.
Like carbon, nitrogen can be combined with other
chemical elements in different ways. The various
combinations result in many different proteins. Each protein
is made up of several nitrogen compounds called amino
acids. These amino acids are the "building blocks" from
which proteins are made. The chemical arrangement of the
amino acids determine the quality of the protein.
During digestion, proteins are broken down into amino
acids. These are absorbed from the intestine into the blood
stream and carried to all parts of the body. Then they are
recombined to form body tissue.
Proteins that are eaten eventually become muscle,
internal organs, bone and blood. Skin, hair, hooves, and
many other parts of the body are also made of protein. If an
excess of protein is fed, the nitrogen portion of the protein
can be separated from the rest of the nutrient and be
discarded in the urine. The remaining materials can then be
converted into energy by the animal.
TWO PROTEINS ARE NOT ALWAYS ALIKE IF
MADE OF THE SAME AMINO ACIDS!
AMINO ACIDS 1ii2
PROTEIN #1 PROTEIN #4
I1 1 2 =iff iI=
Although animals need large amounts of both energy
and proteins, other nutrients are just as vital, but are needed
in much smaller amounts. The vitamins are such a group.
For a long time, people noticed that certain diseases
were caused by the lack of certain foods. Then modern
science began analyzing the foods. They were found to
contain small amounts of certain complex chemicals. Other
foods did not contain them.
These nutrients were called vitamins, or "vital amines".
They are essential to normal body functioning.
The vitamins are not chemically alike. Each one also
has a different job in the body. Still, they are all classed
together under the term vitamins. This is because they are all
organic compounds. (They contain carbon). Also, all of
them are needed only in very small amounts.
Vitamin A is responsible for the health of the eye and
the tissue of nasal passages, lungs and digestive system.
Vitamin D is responsible for the strength and proper
development of bones and the mineral balance in the blood.
Other vitamins have just as important functions.
Some animals require only certain vitamins in their
feed, whereas others can manufacture some of their own.
Feeds are a good source of certain vitamins. Carotene in
green grass is a good source of vitamin A. Sunshine and sun-
cured hay are good sources of vitamin D.
Like vitamins, minerals are usually needed only in small
amounts. Unlike vitamins, they are inorganic they do not
contain carbon. Iron, copper, phosphorus, calcium, and
magnesium are examples of minerals.
Horse Science: Feed Nutrients
Minerals are important in the chemical reactions of the
body. Without them, many life processes could not take
place. Without iron in the blood, for instance, oxygen could
not be carried to the body's cells. For animals such as horses
that are very active, the oxygen carrying capacity of the
blood is a very vital factor in their daily life. A race horse
uses tremendous quantities of oxygen during a race.
Without calcium and phosphorus proper bone and tooth
formation would not take place. These are examples of the
need for minerals.
WATER AS A NUTRIENT
The last item on our list of nutrients is so common that
we seldom think of it as a nutrient. But water is the largest
single part of nearly all living things. The body of a colt is
three-fourths water, while an adult is approximately 50
Water performs many tasks in the body. It makes up
most of the blood, which carries nutrients to the cells and
carries waste products away. Water is necessary in most of
the body's chemical reactions. In addition, water is the
body's built-in cooling system. It regulates body heat. It acts
as a lubricant.
Life on earth would not be possible without water. An
animal can live longer without food than without water.
FINDING OUT WHAT'S IN FEEDS
Research has provided the information that is available
about the different kinds of nutrients. The scientist has
developed methods by which the amount of each nutrient in
a feed can be accurately determined. Knowing the nutrient
content of a feed is very important to livestock raisers.
Water is one of the nutrients that is fairly easy to
determine. Simply take a sample of a feed and weigh it.
Then heat the feed sample slightly above the boiling point of
water. Hold it at this temperature until the feed stops losing
weight. Then weigh the feed. This weight is subtracted from
the weight before heating. The difference between the two
weights represents the amount of water driven off by the
heat. To find the percentage of water, divide the dry weight
by the original weight.
Another fairly simple analysis is to find out how much
mineral is in the feed. Recall that minerals are inorganic
chemicals. As such they will not bur. When feed is
completely burned, a whitish-gray ash is left. If the weight
of this ash is divided by the original weight of the feed
before burning, the percent mineral, or ash, is obtained.
The chemical analysis gets more complicated when you
are determining how much protein is in a feed. Recall that
protein is made up of carbon, hydrogen and oxygen plus
nitrogen. Scientists have learned that protein is about 16
percent nitrogen. Using certain chemical tests, the amount of
nitrogen in a feed can be determined. Multiplying this
amount by 6.25 (16 percent nitrogen divided into 100=6.25)
gives the amount of crude protein in a feed. It is called crude
protein because it includes all nitrogen compounds. There
may be some nitrogen compounds in the feed which are not
Another test is for the amount of fat in a feed. Since fat
dissolves in ether, a sample of the feed is heated in ether for
several hours. Then the feed is removed, and the ether is
evaporated. The residue that is left is the fat, or ether extract.
It is important to know the fiber content of feeds. This
is because fiber is hard to digest. Therefore, feeds with a
high fiber content are less nutritious.
To find the fiber content, some of the feed is dissolved
in a weak acid or alkali. Fiber (very complex carbohydrates)
will not dissolve; it is left over. Any material that the weak
acids or alkali will not dissolve is considered to be
indigestible by animals. Keep in mind that the cells in the
lining of the stomach secrete a weak solution of
If the percentage of water, minerals, fat, fiber and
protein are added together, the total will be something less
than 100 percent. This difference is referred to as the
nitrogen-free extract. This extract includes the more soluble
carbohydrates, sugars, starch and some cellulose. All of
these are readily digested in the digestive tract.
When the amounts of different nutrients in a feed are
known, the quality or feeding value of the feed can be easily
determined. By adding the digestible organic nutrients
(protein, nitrogen-free extract and fat x 2.25), we can tell the
c nc i in value" of a feed TDN total digestible nutrients is
the term used.
ORGANIC MATTER ASH
NITROGENOUS SUBSTANCES NON-NITROGENOUS
I I- -I-I I I
TRUE NON-PROTEIN CARBOHYDRATES FATS
SOLUBLE CARBOHYDRATES CELLULOSES,
(NFE) FIBERS, ETC.
Horse Science: Feed Nutrients
Horse Science: Feed Nutrients
1. This document is section 8 of 14 of 4HHSGO1, which supersedes CO 201, one of a series of the 4-H Youth
Development Program, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University
of Florida. Date first printed August 1965. Date revised June 1989. Please visit the FAIRS Website at
.-'. UNIVERSITY OF
Cooperative Extension Service
Institute of Food and Agricultural Sciences
2. H. B. Hedgepeth, Mississippi State University; T. W. Wickersham, Iowa State University. Debbie Glauer, member
of 4-H Animal Science Design Team, Department of Family, Youth and Community Science, Cooperative Extension
Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, 32611.
COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF FLORIDA, INSTITUTE OF FOOD AND AGRICULTURAL SCIENCES, Christine
Taylor Waddill, Director, in cooperation with the United States Department of Agriculture, publishes this information to further the purpose of
the May 8 and June 30, 1914 Acts of Congress; and is authorized to provide research, educational information and other services only to
individuals and institutions that function without regard to race, color, age, sex, handicap or national origin. The information in this publication
is available in alternate formats. Single copies of extension publications (excluding 4-H and youth publications) are available free to Florida
residents from county extension offices. Information on copies for out-of-state purchase is available from Publications Distribution Center,
University of Florida, PO Box 110011, Gainesville, FL 32611-0011. Information about alternate formats is available from Educational Media and
Services, University of Florida, PO Box 110810, Gainesville, FL 32611-0810. This information was published June 1989 as CO 201, which is
superseded by 4HHSG01, Florida Cooperative Extension Service.