1/24/20131WATERConsidered the most essential nutrient Lack of performance Death – When is dehydration fatal?Most abundant nutrient in body Inexpensive, but often over-lookedNot stored Daily excretion = intakeWater balance is achieved through regulation of electrolytesWATER1/24/20132Water content of tissues:Distribution of body waterBODY WATER COMPOSITIONTissue % WaterMuscle 75Adipose 15Bone 30Tooth 5Location %Intracellular 50Interstitial 15Extracellular 5GI tract remainder % body water decreases with age Inverse relationship with body fatBODY WATER AND AGE0204060801001208 30 100AshFatProteinWater1/24/20133SolventTransportationChemical reactionsLubrication and cushioningTransfer of light and soundRegulation of temperatureRegulation of ionic concentrationsFUNCTIONSDrinkingFeedMetabolic waterWater liberated during metabolic reactions or catabolism of body tissueImportance depends on species, diet, habitat, and ability to conserve waterSOURCES OF WATER1/24/20134Monogastric Net absorption Net secretionRuminant  Net absorption Net secretionWHERE DOES WATER ABSORPTION AND LOSS OCCUR?Sources of water loss?WATER IN FEEDFeedstuff Water % DM %Coastal Hay 12.9 87.1Corn 11.9 88.1Corn Silage 64.9 35.1Alfalfa Haylage 57.4 42.6Cottonseed Meal 9.5 90.51/24/20135When carbohydrates, fats, and protein are used in the body for energy using oxygen, carbon dioxide and water are produced10% of total intakeMETABOLIC WATERNutrient g of water produced/100 g Carbohydrate 60Fat 108Protein 42Digestive systemBreed (genetics)Environmental temperaturePhysiological functionDisease conditionWater qualityFACTORS AFFECTING WATER INTAKE1/24/20136Inorganic toxins Nitrate, fluoride, metalsOrganic toxins Pesticides, hydrocarbonsPathogenic organisms Bacteria, algaeCa, Mg, Na salts Chlorides, carbonates, bicarbonate, sulfateFACTORS AFFECTING WATER QUALITYIncrease In Water ConsumptionFeed WaterDM IntakeProtein ContentSalt ContentIndigestible FiberDIETARY FACTORS AFFECTING WATER INTAKE1/24/20137Rule of thumb Most animals consume 10% BW in water daily 2 – 5 kg water/kg feedAnimal Gallons/dDairy 10 – 16Beef 8 – 14Sheep 1 – 3Horse 8 – 14Swine 2 – 4HOW MUCH WATER? Water and impaction colic in horses Fluid media needed for fiber fermentation in hindgut When water deprived there is fluid movement from gut to vascular Dry fiber in large intestine impacted Decreased gut motility and impaction = abdominal pain Must rehydrate horse and GI contentsWATER AND ANIMAL HEALTH1/24/20138 Anions and cations distributed throughout the fluid compartments Maintains electrical neutrality Cations: Na, K, Ca, Mg Anions: Cl, HCO3, SO4, proteins, lactic acid Critical to maintenance of acid/base balance Influence water retention Na Cell survival depends on water uptake and loss Rupture vs. collapseELECTROLYTESELECTROLYTE COMPOSITION OF BODY FLUIDSPlasma (mEq/L) Interstitial Fluid (mEq/L H2O)Intracellular Water (mEq/L H2O)Cations 153 153 195Na+142 145 10K+4 4 156Ca+252-33Mg+221-226Anions 153 153 195Cl-103 116 2HCO3-28 31 8Protein 17 --- 55Others561301/24/20139Electrolyte balance and the corresponding movement of water dictates Osmotic pressure – pressure that develops when two solutions of different concentrations are separated by a membrane Water moves via osmosisOSMOTIC PRESSUREK = 156Na = 10K = 4Na = 142The body’s extracellular water volume is determined by osmolarity (concentration of a solute in solution) Signal for regulatory factors Short term (rapid) control Lungs Chronic (long-term) control GI tract KidneysOSMOLARITY1/24/201310Useful in treating dehydration Causes?Preparations are species specificMethods of administration?ELECTROLYTE