Vitamins
• organic substances in natural foods
• produced within the body - synthesized by microbes
• stabled horses may need supplemental vitamins
• vitamin A
– vision
– cellular differentiation
– bone remodeling
– carotene
• destroyed by heat, light, wet hay, storage
– may want to supplement in winter
Vitamin A
• deficiency
– poor bone development
– poor night vision
– extreme deficiency
• excessive tear production
• infertility in mares
– feeds supplemented 10,000 iu/kg
• toxic 5X
• vitamin D
– maintain calcium:phosphorus homeostasis
• blocking agents
– synthesized in body with sunlight
– deficiency of Vitamin D
• depressed blood Ca draws Ca from bone
• lameness
• bone fractures
– requirements not established
– deficiency and toxicity same symptoms
Vitamin E
• antioxidant value
– related with selenium
• deficiencies associated with myopathies in foals
• requirements not established
– ? - hard-working horses may have muscular problems
with deficiency
• destroyed with oxidation
– moisture and storage
– moldy hay
– ground grains
• deficiency
– neurological diseases
• B complex vitamins
– adequate in forages and synthesized by bacteria in LI
– exceptions
• thiamine
– role in energy metabolism
– heavy exercise may be marginal deficiency
– deficiency
• ? lack of coordination in hind end
• heart problems
• folic acid
– decrease with months of intense exercise
– decrease with prolonged stabling
– give access to pasture
• B12
– contains cobalt
– deficient areas
• deficient in ruminants
• ? anemia and decreased RBC in horses
• biotin
– water soluble
– availability
• wheat, barley, milo: low
• oats : medium
• corn : available
– deficiency
• cracked hooves
– 15 mg/day
• water
– most important nutrient
– lack of H2O more serious than any other nutrient
– lost in urine, feces, sweat, evaporation
– increased water consumption with hay and grain
– idle horse drinks 28 liters/day - cool weather
– “
“
“
80 liters/day - hot weather
– increased water intake with exercise
• 3 % of BW loss of water affects performance
• 5-10% of BW loss during endurance race
Ration Formulation
• ration dependent on level of activity
– idle horse - good roughage and salt/mineral block
• 450 kg horse needs about 15,000 kcal/day energy
– exercising horse - roughage and concentrate
• energy increase usually fulfills protein, vitamin and
mineral increase, except calcium
– increase energy intake by adding fat
• “calorie” - = 1 kilocalorie
– amount of energy required as heat to raise the
temperature of 1 kg of water by 1o C
– 1000 kcal in 1 megacalorie (Mcal)
– DE and TDN
– % BW
• .5 % BW/day as roughage
Sprinting Vs. Endurance
• grain:hay ratio varies
• sprint
– maximum hay/day 1.5% BW
• hay retains a lot of water in the gut
• endurance
– advantageous to feed hay - 1.5 to 2% BW
• retains water
– add fat (up to 15 % of total ration)
Day of Competition
• H2O available at all times
• endurance/eventing
– feed hay and grain 4 hours prior to competition
• glucose and insulin stabilize
• continuous water
• electrolytes
• sprinting sports
– also 4 hours prior to competition
Glycogen
Loading
• enhance performance by delaying glycogen depletion
• manipulation of diet in humans
– exhaustive exercise - low CHO diet
– light exercise - high CHO diet
• replenish glycogen over normal resting stores
• horse
– conditioned horse has large amounts of glycogen
– high CHO diet - laminitis or tying-up
• Table 13.1 and 13.2