Transcript nutrition
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