Water

Water is a polar molecule composed of

1 oxygen and 2 hydrogen atoms

Water Sources

• Feed water

• Drinking water

• Metabolic water

Feed water is moisture in feed that

is not chemically bound to the feed nutrients

Concentration of feed water is highly variable

depending on the feed source.

Grains are generally around

8 – 12% water

Forages can range from around

5% in hays to upwards of 90% in lush pasture

Silages range from

30 – 50% water

Dry matter is what remains

after all water is evaporated out of a feed: grain and fresh or dried forages.

Dry matter is an indicator of the amount

of nutrients that are available to the animal in a particular feed.

Livestock need to consume a certain amount of dry matter per day
(lbs or kg/day)

to maintain health and production.

The daily amount of dry matter needed depends upon several factors
including,

weight and stage of production (e.g., lactating, pregnant, weaning, finishing).

Metabolic water is water chemically bound and released when

nutrients or body tissues are broken down during metabolism

Metabolic water depends on the

nutrient being broken down

Metabolic water can account for

5 – 10% of the daily water needs of the animal.

Water Losses

• Feces

• Urine

• Dissipation from the skin surface (sweat)

• Milk

• Eggs

Water loss in feces is

highly variable among species

Feces

• Cattle will lose variable amounts of water
  depending on diet

• Sheep and goats are more efficient as water
  resorption, hence the fecal pellet

• Pseudoruminants have extended colons to aid in
  water reabsorption

Losses to urine, with the exception of the lactating female, account for

the largest amount of water loss in the animal

Water loss in the urine is regulated

by the kidneys

Urine

• Species adapted to hot, dry climates will develop kidneys that are
  more efficient at water conservation

• Species adapted to wet climates will tend to produce more dilute
  urine

• High protein diets or diets high in mineral salts will increase loss of
  water through the urine

Loss of water through respiration or dissipation from the skin is

highly dependent on environmental conditions

Respiration and Dissipation

• In hot conditions, evaporative losses are used as a
  means to cool the body

• Increase air movement will increase water
  requirements of the animal