Six major classifications of nutrients are:

• vitamins
• minerals
• proteins
• carbohydrates
• fats
• water

(if, during a knowledge competition, you are asked for five, leave out water, although it IS the most important)

• water may be considered the most important nutrient
• dehydration can kill faster than any other deficiency
• the adult horse is sixty-six percent water
• water should be available to the horse at all times, except, of course, when he is hot due to exercise
• the adult horse will drink about ten gallons of water per day
• water intake will increase during excessively hot weather, or during lactation in the mare
• water should be kept fresh and clean, and buckets should be disinfected regularly
• water containing salt or high amounts of fluoride should be avoided
• since the mineral content of water alters the flavor, it is a good idea to add molasses to the water for a few days before and during any trip

• vitamins were first discovered in 1912
• the word vitamin comes from vita, which means life, and amine, which means nitrogen compound
• the first individual vitamin to be recognized was vitamin A in 1913
• vitamins are divided into two categories, fat soluble and water soluble
• fat soluble vitamins include A, D, E, and K
• vitamin C and the B complex vitamins are soluble in water
• vitamins are measured in international units, or I.U., when discussing equine nutrition, but they may also sometimes be measured in milligrams
• Vitamin A
  • soluble in fat
  • necessary for:
    • the health and maintenance of the nasal passages and the membranes in the respiratory tract
    • the transmission of nervous impulses, especially in the optic nerve
    • stimulating growth and appetite
    • assists in reproduction, digestion, and lactation
  • vitamin A is synthesized from carotene in the intestinal wall
  • deficiency of A isn't caused by a lack of the nutrient in the diet, but rather by parasite infestation or other health problem
  • vitamin A deficiency can cause:
    • muscle incoordination
    • excessive lacrimation (watering of the eyes)
    • poor appetite
    • reproductive failure
    • predisposition to respiratory ailments
    • nerve degeneration
    • eyesight problems
    • poor hoof development
  • it is the constriction and degeneration of the optic nerve that will lead to blindness
  • night blindness is also related to vitamin A, although there are many other factors involved
  • recommended levels of vitamin A are between five thousand and sixty thousand I.U. Adult horses in training need approximately forty thousand I.U. per day, with stallions needing slightly more, their requirement being around sixty thousand I.U.
  • one milligram of carotene is synthesized into four hundred I.U. vitamin A The B
  • complex vitamins
  • soluble in water
  • synthesized in the large intestine
• the B-complex vitamins include:
  • thiamine, or B1
  • riboflavin, or B2
  • pyxidoxine, or B6
  • cobalamin, or B12
  • nicotinic acid
  • panthothenic acid
  • biotin
  • folic acid, or folicin
  • choline
  • inositol
• in general, B vitamins are necessary for:
  • cellular metabolism
  • the formation of co-enzymes
• (specific vitamins have specific metabolic functions)
• thiamine, or B1, is essential in appetite and growth promotion, as well as carbohydrate metabolism, and nervous regulation
• riboflavin, or B2, aids in vitamin C synthesis and protein metabolism
• riboflavin is highly resistant to destruction
• pyridoxine, or B6, is used in the metabolism of fats and proteins
• cobalamin, or B12, is essential for cell division and blood formation
• cobalamin is the only vitamin to contain a metal, including cobalt in its makeup
• niacin, or nicotinic acid, is responsible for hydrogen transport
• choline is used in transporting nerve impulse and is found in co-enzymes
• folic acid, or folacin, is involved in cellular metabolism as well as the formation of red blood cells
• biotin acts as a co-enzyme
• pantothenic acid affects the nervous system and is a co-enzyme
• inositol is also a co-enzyme
• B-complex deficiencies have a variety of symptoms and results, including poor growth and appetite in most cases
• niacin deficiency will cause retarded growth and appetite, rashes, diarrhea, and nervous disorders
• a deficiency in folic acid will cause anemia
• both choline and cobalamin deficiencies produce retardation of growth
• pantothenic acid deficiency causes nerve disorders and skin rashes
• riboflavin deficiency can cause poor feed efficiency, decreased growth, porous bones, impaired joints and ligaments, and can contribute to Periodic Ophthalmia (moonblindness)
• thiamine deficiency causes weight loss, loss of appetite, incoordination (especially in the hindquarters) elevated levels of pyruvic acid in the blood, enlarged heart, and nervous symptoms
• biotin deficiency can cause hair loss and lack of appetite
• inositol and pyxidorine deficiencies are rare, since they are both synthesized in the large intestine and are abundant in grains
• B-complex vitamins can be supplemented with Brewer's yeast, commerical vitamins, and sometimes fish oil meal
• Vitamin C
  • soluble in water
  • vitamin C is also called ascorbic acid
  • necessary for:
    • the construction and maintenance of intercellular material
    • the proper healing of wounds
    • resistance to disease
    • synthesis of certain amino acids
  • Vitamin C deficiency is scurvy
  • scurvy causes:
    • the loosening of teeth
    • weakening of bones
    • weakening of capillary walls
    • wounds are slower to heal
    • lower resistance to disease
  • scurvy is rare in horses, however, unless something interferes with the synthesis of the vitamin
  • synthesized by the horse in large quantities
  • vitamin C is found in growing plants (also citrus fruit)
• Vitamin D
  • fat soluble
  • necessary for:
    • controlling the mineral balance in blood plasma
    • the utilization of calcium and
    • phosphorus (hence bone strength)
  • vitamin D is biochemically manufactured in the skin using ultraviolet rays from the sun, as well as organic compounds already found in the skin
  • vitamin D deficiency causes:
    • reduced bone calcification
    • stiff and swollen joints
    • stiffness of gait
    • soft bones
    • bone deformities
    • mineral deposits on the skull
    • predisposition to fracture
    • a reduction of calcium and phosphorus in blood serum
  • vitamin D recommendations vary from seven hundred and fifty international units in the suckling foal to between six thousand and nine thousand I.U. in the adult horse.
• Vitamin E
  • soluble in fat
  • vitamin E is made up of tocopherols
  • necessary for:
    • preventing the destruction of vitamin A
    • repair
    • reproduction
    • hoof health
    • oxygen transport
    • muscle development
    • erythocyte (red blood cell) production
  • vitamin E deficiency causes:
    • anhidrosis (an inability to sweat)
    • poor reproductive ability
    • myositis, (a mild case of azoturia)
    • muscular distrophy in foals
    • degeneration of muscle
    • predisposition to azoturia
    • poor hoof development
    • loss of appetite
    • nerve degeneration
    • muscle incoordination
  • vitamin E deficiency can also cause eye problems such as lacrimation, night blindness, and in extreme cases, total blindness due to vitamin A destruction
• Vitamin K
  • soluble in fat
  • necessary for: production of prothrombin in the liver for use in blood clotting in the event of an injury
  • green, leafy plants provide an adequate supply of the organic substances used in the synthesis of vitamin K in the intestinal tract
  • certain molds which can be found in poor quality hay can cause the destruction of this vitamin, and antimetabolites in medical treatments and sometimes even in the ration can lessen vitamin K availability
  • deficiency can result in hemorrhaging to death
  • certain breeds may have higher vitamin K requirements than others, and there may be variations within breeds based on different bloodlines (Vitamin K requirements are hereditary)
  • sources of vitamin K, in addition to natural synthesis, include green plants and alfalfa pellets, as well as synthetic supplements
  • supplementation is recommended during late gestation, and whenever there is a high risk of injury. Also, some young foals lack the ability to synthesize vitamin K during their first one to four weeks of life and should be given supplements if surgery is necessary.

• minerals are inorganic compounds that are vital to a horse's metabolism
• the most popular method of mineral supplementation is free choice, using mineral blocks
• mineral blocks and boxes should be protected from the weather, and they need to be low enough for foals to reach them as well. Free choice minerals will be frequently utilized if they are kept near the water supply, and will be safer if kept out of the way, so horses will not bump into them.
• some factors involved in mineral intake are the mineral level of the soil, the time of year, and the palatability of the mineral mixtures provided.
• factors which effect mineral requirements include heredity; size; growth rate; work level; total feed intake; mineral level of hay, pasture, grain, and water; reproduction; lactation; gestation; environment and stress.
• most minerals are interrelated (ie calcium and phosphorus)
• Related Minerals
  • perhaps the most well known mineral relationship is the one between calcium and phosphorus, which also includes vitamin D
  • magnesium is related to iron, as well as to calcium and phosphorus
  • excess calcium reduces zinc absorption, causing a greater zinc requirement, and can also increase the requirements of copper, manganese, iron, iodine, phosphorus, and magnesium
  • increased copper intake raises the need for zinc and iron
  • there is an interrelationship between sulfur, copper and molybdenum in ruminants (animals with four stomachs)
  • excess potassium increases the salt requirement in the cow, and recent studies indicate an interrelationship
  • minerals can also be interrelated to vitamins, for example selenium and vitamin E
  • calcium, phosphorus and vitamin D are all related
  • amino acids can even be related to vitamins, for example niacin and tryptophan, or methionine, cystine, selenium and vitamin E
• Calcium and Phosphorus
  • the ratio of calcium to phosphorus is two to one in the body, and should be between 1.1 to 1 and 1.5 to 1 in the diet (phosphorus is not completely utilized)
  • necessary for:
    • building/maintenance of bones and teeth
    • lactation
    • disease prevention
  • phosphorus is also used in fat metabolism, enzymes, and the metabolism of carbohydrates
  • calcium deficiency is called rickets
  • calcium deficiency causes ostemalacia, a condition in which calcium and phosphorus are removed from the bones. This forms weak, brittle, and porous bones. Blood calcium is not a reliable indicator of calcium in the diet, since the hormone calcitonin causes calcium to be removed from the bone when blood calcium decreases.
  • calcium is regulated by calcitonin, a hormone produced by the parathyroid gland, as well as by estrogens
  • a high intake of calcium and phosphorus will increase requirements for magnesium, zinc, copper and vitamin D
  • calcium and phosphorus are both closely related to vitamin D, and they cannot be utilized without it
  • hays are generally higher in calcium and grains in phosphorus
  • bran is higher in phosphorus than most feeds (soybean oil meal, a protein supplement, is also high in phosphorus)
  • calcium supplements include limestone and calcium phosphate
  • steamed bone meal supplies both calcium and phosphorus, but has palatability (taste) problems
• Selenium
  • closely related to vitamin E, as well as the amino acids methionine and cystine
  • necessary for:
    • sulfur amino acid synthesis
    • the immune response
    • as component of the enzyme glutathione peroxidase
  • selenium deficiency can cause:
    • white muscle disease
    • azoturia
  • symptoms of white muscle disease include muscle stiffness, hair loss, brown urine, and difficulty in walking
  • approximately .1 parts per million are required to avoid a deficiency
  • selenium toxicity does occur in climates with high selenium levels, and it is fatal to horses
  • symptoms of selenium toxicity include hair loss and the appearance of a ring around the hoof
• Potassium
  • necessary for:
    • muscle activity
    • carbohydrate metabolism
    • enzyme reactions such as phosphorylation of creatine
    • the production of intracellular fluid which is involved in osmotic pressure
    • the maintenance of a stable acid-alkali balance in the cells
  • potassium deficiency can cause:
    • growth retardation
    • unsteady gait
    • muscle weakness
    • pica
    • diarrhea
    • distended abdomen
    • emaciation
    • odd electrocardiograms
    • eventual death
  • potassium deficiency can be caused by rapid excretion of body fluids during serious illness. Although deficiency is unlikely, it could cause permanent damage to kidneys and the heart
• Salt
  • salt contains equal proportions of sodium and chloride
  • necessary for:
    • regulation of fluid balance in the body
    • bone mineralization
    • nutrient transport in cells
    • muscle contraction
    • bile production
    • the production of hydrocloric acid
  • a salt deficiency causes:
    • poor appetite
    • heat stress
    • reduction of lactation
    • a rough hair coat
    • growth reduction
  • about sixty grams of salt are required daily by the horse
  • salt may be added to the ration, or be fed freely either in loose or block form. Salt blocks may be trace mineralized, iodinized, or plain.
  • iodinized mineral blocks are recommended in the goiter belt (region of the US with soil low in iodine)
  • when feeding trace mineralized salt, it may be necessary to also make plain salt available, because many horses will not consume enough trace mineralized salt to meet their daily salt requirement
• Magnesium
  • magnesium is composed of mucopolysaccharides
  • necessary for developing the organic matter in bone
  • magnesium deficiency can cause:
    • lameness
    • shortened legs in offspring
    • enlarged hocks
    • deafness in offspring
    • "overknuckling"
    • increased fractures
    • muscular twitching
    • nervousness
    • hard breathing
  • the magnesium requirement for an adult horse is approximately forty parts per million, but it increases with high intake levels of calcium, phosphorus, potassium, and aluminum
  • oats contain thirty
  • eight parts per million magnesium
  • corn is low in magnesium, however, with a magnesium content of only four parts per million
  • soybean meal, a common protein supplement, contains forty parts per million
• Fluoride
  • fluoride is necessary for bone development
  • excess fluoride causes irreversible bone damage
• Aluminum
  • aluminum is required in small amounts
  • high aluminum intake increases magnesium requirements
• Trace Minerals
  • required only in minute amounts
  • trace minerals include cobalt, copper, Iodine, iron, manganese, and zinc
• Iodine
  • necessary for: the production of thyroxin by the thyroid gland
  • iodine deficiency causes:
    • goiter (swelling of the thyroid gland)
    • stillborn foals
    • naval ill in foals
  • the iodine requirement for an adult horse is about .1 parts per million
  • iodine toxicity usually doesn't occur until at least two hundred parts per million are present in the diet
• Zinc
  • necessary for:
    • enzyme and hormone production
    • healthy lymphocyte and neutrophil cells
  • zinc deficiency is called Parakeratosis
  • Parakeratosis causes:
    • loss of appetite
    • hair loss
    • lack of growth
    • dermatitis with mangelike symptoms
    • lesions of the hoof area
    • poor healing ability
    • abnormalities in the immune system
    • retardation of bone calcification
    • abnormal reproduction
    • birth defects
  • a horse's zinc requirement is about forty parts per million, and is higher in colts, stallions and geldings than in fillies and mares
  • zinc toxicity can cause stiffness and the enlargement of the ephiphyetes (growth plates)
• Iron
  • iron affects all organs
  • necessary for:
    • the formation of erythocytes and hemoglobin
    • the functioning of the enzyme systems
  • the horse's iron requirement is one hundred fifty parts per million
  • iron deficiency causes:
    • anemia (decrease in red cells)
    • lack of energy
  • iron toxicity is unlikely, as it takes five thousand parts per million to overdose
• Copper
  • necessary for:
    • utilization of iron in the production of hemoglobin
    • proper bone formation
  • copper deficiency causes:
    • abnormal bone development in foals
    • inability to absorb iron
    • anemia
    • exostosis (cartilage growths)
• Cobalt
  • cobalt is necessary for the synthesis of the B-complex vitamin cobalamin, or B12, in the intestinal tract
  • cobalamin is the only vitamin known to contain a metal, and it is four percent cobalt
  • cobalt deficiency can cause:
    • normocytic normochromic
    • anemia
    • cobalamin deficiency
• Manganese
  • necessary for:
    • enzyme systems
    • growth
    • reproduction
    • bone development
    • lactation
    • the formation of glycoproteins
    • metabolism of fats, proteins, and carbohydrates
    • reduction of stress

• proteins are made up of amino acids
• different tissues are made from different amino acids
• amino acids are divided into two major groups, essential and non
• essential amino acids
• both are vital to metabolism, but non-essential amino acids aren't needed in the diet because they are synthesized in the large intestine
• essential amino acids must be supplied in the ration, because they cannot be synthesized by the horse
• proteins are used primarily for growth and repair, and the excess are burned for energy
• proteins are needed for healthy tissues and a glossy coat of hair
• the twenty essential amino acids are lysine, tryptophan, threonine, methionine, alanine, arginine, aspargine, aspartic acid, cystine, glutamic acid, glutamine, glycine, histidine, isoleucine, leucine, phenylaline, proline, serine, tyrosine, and valine.
• amino acids are not stored by the body, and excess are burned as energy
• the horse needs to have all essential amino acids fed together, or one will be disposed of before the second arrives to combine with it
• many plant protein supplements, with the exception of soybean meal, are lacking in the amino acid lysine.
• legume hays are higher in protein than grass hays
• the most common and probably beneficial protein supplement used is soybean meal
• whole soybeans are not fed to horses because they contain a trypsin inhibitor, which interferes with amino acid breakdown. Heat from processing destroys the inhibitor.
• the second ranked protein concentrate in this country is cottonseed meal, although it is deficient in lysine
• linseed meal is also a common protein supplement

• carbohydrates are the horse's primary energy source, but fats and proteins may also be burned for energy
• energy is defined as the capacity to do work
• energy is used for metabolism, activity, growth and repair, reproduction and lactation.
• one way to determine the energy content of the ration is TDN (Total Digestible Nutrients).
• TDN is determined by rating digestibility of nutrients in various feeds. The nutrient content is multiplied by the digestibility, and the total digestible content is given.
• total digestible protein, total digestible carbohydrates, and total digestible fats (multiplied by 2.25) are then added together to find the total digestible nutrients for that feed.
• the average horse requires ten units TDN per day.
• another method of measuring energy is by calorie. A calorie is a heat measurement, and calorie content must be determined in a lab by burning the feed.
• figuring out the exact energy contents of rations can save money and avoid waste without scrimping on quality
• Carbohydrates
  • carbohydrates are organic compounds containing carbon and water which are used for energy and the production of ATP (adenosine triphosphate)
  • carbohydrates include starches, cellulose, and sugars, and are found in all feeds
  • carbohydrates are the horse's main source of energy, and they form more than sixty percent of most hays and grains
  • carbohydrates are also necessary for the oxidation of fats; when carbohydrates are oxidized, they produce pyruvic acid, which is used to oxidize fats
  • cellulose, a major part of dietary fiber, is digested by bacteria in the large intestine and changed to volatile fatty acids which are metabolized by the tissues
  • hemicelluloses are also carbohydrates. They are, like cellulose, part of the cell wall in plants, but are more digestible.
  • both hemicellulose and cellulose stimulate peristalisis
  • nitrogen free extract, or starches and sugars, are found in concentrates
  • starches and sugars are synthesized into a simple sugar such as glucose and then utilized
  • carbohydrates are highly digestible, and are the most easily obtained of the energy sources.
• Fats
  • lipids are fats, oils, and waxes found in feeds, and they are essential to metabolism
  • all lipids are organic and contain carbon, hydrogen, and oxygen
  • the term "lipids" includes glycerides, cholesterol, lecithin, chlorophyll, volatile oils, and resins, as well as fats
  • fats are broken down into fatty acids, which serve several functions.
  • lisnoleic acid is required for skin growth and condition in young horses
  • only a small amount of lipids are needed, and most are burned as energy or are stored. They also help form cell membranes and are used in vitamins and hormones.
  • fats provide more concentrated energy than either proteins or carbohydrates. When there are adequate amounts of fat in the diet, they are used as energy, leaving proteins for muscle development.
  • lipids are less stable than other nutrients, making foods high in fat, such as corn, more perishable than feeds with a lower fat content
  • high fat content increases palatability

• the two main classifications of feed for horses are hays, or roughages, and grains, or concentrates
• grains are generally higher in energy, and are needed in smaller amounts
• high quality hay is essential to the horse's diet. Sun cured hay is the stabled horse's primary source of vitamin D, and hay supplies energy, calcium, protein, vitamins, and trace minerals. It is high in fiber and stimulates peristalisis.
• a hay may be classified as either a grass hay or a legume hay
• legume hays are leafier than grass hays, are higher in protein, and are higher in calcium and phosphorus
• since feeding legume free choice can result in colic due to high energy and protein levels, it is advisable to mix them with grass hays so they are not too rich
• the most popular legume hay used for feeding horses is alfalfa. It is high in carotene, which the horse uses to synthesize vitamin A, and haygrowers like alfalfa because it can produce three times more hay per acre than most grass hays. Several cuttings can also be harvested.
• second cutting alfalfa cut in early
• bloom has a protein content of 18.4 percent, 12.3 percent of which is digestible. In full bloom it contains 9.9 percent digestible protein, and at maturity it contains 7.7 percent digestible protein. Alfalfa hay is thirty percent fiber.
• alfalfa contains more nutrients per pound than any other hay and is extremely high in energy.
• alfalfa is best when mixed with a grass hay, the most popular being timothy.
• other legumes include red and white clover, lespedeza hay, and birdsfoot trefoil
• grass hays aren't as rich as legumes. They are lower in protein and nutrient content, with the average digestible protein level at about eight percent. Grass hays can be fed freely since they aren't likely to cause colic or founder. They are often mixed with legume hays to make a ration which is lower in protein than pure legumes, and is therefore safer to feed.
• one of the most popular grass hays fed to horses is timothy. It is grown most successfully in the northern part of the country, and is average in nutrient content. One of the reasons for its popularity is the fact that it tends to be mold and dust free.
• other grass hays include bermuda hay (ie Coastal Bermuda), big bluestem, little bluestem, bromegrass hay, wheatgrass, and prairiegrass.
• no hay should be fed if it is moldy, fermented, weedy, or coarse and stemmy
• excessively dusty hay should be avoided, since it can contribute to heaves
• horses with heaves should have their hay wet down to reduce the dust
• hay should never be stored wet, since it could cause a barn fire by building heat and spontaneously igniting
• grains include corn, oats, barley, linseed, bran, and commercial pellets
• oats were once considered to be the safest grain to feed to horses, but have fallen in popularity
• rolled oats are more easily digestible, and steamed oats are less dusty
• racehorse oats really do weigh more than common oats
• bran can be used as a laxative when fed damp, and is the basic ingredient of the bran mash. It is higher in phosphorus than many grains.
• corn is high in fat, and is more easily spoiled than other grains. The most common variety is dent corn, and it is often mixed with oats. Corn should not be fed to horses while still on the cob.
• commercial pellets are popular, and are one way to insure that all required nutrients are present in the diet, since ingredients and nutrients are listed on the feed bag tag.

• horses are grazing animals which under free-range conditions will eat many small meals, since horses have only a small stomach with limited capacity
• small, frequent meals are much healthier than the two or three meals a day that most stabled horses are fed
• a grazing horse will eat for between ten and twelve hours daily in periods lasting from two to three hours
• usually, horses will not voluntarily fast for more than three to five hours. The hours between one and five in the morning seem to be the longest fasting period.
• as a horse nears the end of a meal, he is more easily distracted. They eat at a slower rate, and may engage in social activity.
• horses will avoid grazing areas which are contaminated with feces, possibly because of the odor
• feeds should be stored in a dry place, preferably where they will be safe from pests. New garbage cans with tight fitting lids are ideal for storing grains, as are commercial feed bins with lids.
• the first priority for feed use is maintenance. Other uses include growth, development, reproduction, lactation, and performance.