Nutrition
• requirements change throughout life
– growth
– pregnancy
– lactation
– work
• essential nutrients
– protein
– **carbohydrates
– **fat
– **minerals
– **vitamins
– **H2O
Protein
• AA - compounds of muscle, enzymes and hormone
• 8-10% protein for mature horse
– ample protein with high quality hay and grain
– poor hay - add SBM, or oilseed products
• quality hay
– limiting AA - lysine and methionine
– excess methionine depletes copper and zinc (hoof wall)
• exercise - little if any increase needed
– usually met with increase of ration
• excessive protein - increased fluid loss in sweat and urine
– need more H2O
Carbohydrate
• primary source in equine diet
• consist of carbon, hydrogen and oxygen
– sugars, starches, celluloses
• absorbed from intestine as glucose
• glucose stimulates insulin release, which lowers blood
glucose
• peak levels of glucose and insulin about 2 hours after
feeding - normal in 5 hours
• excess CHO stored as glycogen in muscle or liver
• exercise - increase grain to hay ratio to increase energy
available
Fat
• concentrated source of energy - twice the calories as CHO
• composed of carbon, hydrogen and oxygen as fatty acids
• feed fat to provide 5-15% of energy in diet
– add fat supplement - raise energy content of ration
without increasing volume
– in pelleted feeds - rancidity
• digest and utilize fats readily - 90%
• absorbed from intestine into bloodstream
• stored as triglycerides in muscle or adipose tissue principal source for aerobic metabolism
Minerals
• inorganic substances
• formation of structural components and energy transfer
• exercise
– maintain osmotic pressure and fluid balance
– activity of nervous and muscular systems
• macrominerals
– calcium, phosphorus, potassium, sodium, chloride,
magnesium, sulfur
• microminerals
– cobalt, copper, fluorine, iodine, iron, manganese,
selenium, zinc
• exercise - sodium, potassium, chloride
– calcium, phosphorus, magnesium and zinc
• excess excreted in urine
• over-supplementation
– one mineral prevents absorption of another
– zinc inhibits calcium and copper absorption
– calcium inhibits zinc absorption
– manganese interferes with iron absorption
• calcium
– 35% of bone structure
– essential for muscle contraction
– formation of hoof wall
– 20 g/day
– exercise - increase calcium met with increase in feed
– hay
• legumes are high in calcium
• grass and grain diet - add calcium carbonate
(limestone)
• phosphorus
– 15% of skeleton
– require for energy transfer reaction - ATP and ADP
– 15 g/day
– calcium:phosphorus ratio 1:1
• potassium
– major intracellular cation
– maintain osmotic pressure and acid-base balance
– 25 g/day to 45 g/day (hard work)
– hays - high in potassium
– grains - low potassium (.3-.4%)
• sodium
– major extracellular cation
– maintain acid base balance and osmotic regulation
– 7.5 g/day for idle horse
– feeds lower than .1 % sodium
– add sodium chloride (salt)
– large increase required with exercise
– can tolerate high levels of salt
– free access to water
• chloride
– extracellular anion
– acid base balance and osmotic regulation
– no requirement established yet
– requirement met with salt
• magnesium
– .05% of body mass
• 60% for skeleton
– activator of enzymes
– 7.5 g/day
– requirement increases for hard working horses
• iron
– constituent of hemoglobin
– limited info on requirements
– adequate amount from feed
– anemia - iron deficiency
• selenium
– component of enzyme glutathione peroxidase
• cell membrane damage
– .1 mg/kg of the diet
– deficient geographic areas
– horses absorb selenium efficiently (77%) / ruminants
(29%)
– deficiency may limit horse’s performance
– can be toxic - 2 mg/kg of the diet