Water

1
Water

• The most vital nutrient

2
Vital role of water

• Body can lose nearly all fat and over half of its
  protein and live
• 10-15 loss of water will result in death

3
Properties and functions of water

• Solvent and ionizing powers
• Ideal for dispersal of organic and inorganic
  molecules
• Facilitation of cell reactions
• High specific heat
• Absorbs metabolic heat
• Helps regulate body temperature

4
Properties and functions of water

• Surface tension
• Reduces evaporation for liquid air interfaces
• Influences pulmonary function
• Facilitates digestion, transportation and
  excretion of other nutrients and metabolites
• Intimate involvement in many biochemical
  reactions
• Reactant (e.g., hydrolysis)
• Product (e.g., oxidation)

5
Body water distribution

• Total body water content is inversely related to
  body fat content
• Water content of lean body tissues is relatively
  constant at 70-75
• urea can be used to estimate lean tissue

6
Body water distribution

• 30-40 of total body water is in extracellular
  fluid
• Blood plasma is 5 of body weight
• Remainder is interstitial fluid
• 60-70 of total body water is in intracellular
  fluid

7
Body water turnover

• Body water turnover is directly related to body
  water content

8
Factors affecting body water

• Genotype
• Bos taurus vs Bos indicus
• Age
• Decreases with age
• Environmental temperature
• Feed quality and quantity
• Physiological state

9
Water content of animal body
10
Sources of body water

• Drinking free water
• In or on feed
• Dry diet vs wet feeds
• Metabolic water from nutrient oxidation

11
Metabolic water

• Glucose 6 O2 6 CO2 6 H20
• Alanine 3 O2 2.5 CO2 CO(NH2)2 2.5 H20
• Palmitic acid 23 O2 16 CO2 16 H20

12
Metabolic water and oxygen
13
Water losses

• Urine
• Ambient temperature
• Digestible dry matter intake
• N intake, metabolism and excretion
• Feces
• Genotype
• Sheep (50-60 water) Cattle (80 water)
• Water intake
• Dry matter intake
• Fiber content of feed

14
Water losses

• Evaporation
• Ambient temperature
• Physiologic state
• Lactation
• Pregnancy

15
Water metabolism (g/d) of sheep
16
Water balance of Holstein cows
17
Water requirements

• Affected by factors that influence water loss
• Dry matter intake
• Recommendations for water intake are often
  expressed in terms of dry matter intake
• Physiological state
• Ambient temperature
• Genotype

18
Average water requirement
19
Water quality

• Salinity (total dissolved solids, mg/liter)
• Slightly saline 1,000-3,000
• Moderately saline 3,000-10,000
• Very saline 10,000-35,000
• Brine (ocean) 35,000
• 3,000-5,000 problem for poultry
• 5,000-7,000 fine after adaptation for dairy and
  beef cattle, sheep, swine and horses
• Tolerance Sheep cattle pigs

20
Minerals in water

• Most abundant salts in saline water
• Na with Ca and Mg
• Carbonates, bicarbonates, chlorides and sulfates
• Sulfates are more harmful than chlorides
• Minerals present include P, Ca, Mg, Na, K, Cl, S,
  Cu, Fe, Mn, Zn, Se, I and Co