Page 50 - Small Animal Clinical Nutrition 5th Edition

50 Small Animal Clinical Nutrition

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Figure 5-1. The six basic nutrients. Carbohydrates, fats and proteins may be used for energy but also serve as structural components.

important nutrient. Water performs the following important
functions in animals:
1. Water is the solvent in which substances are dissolved and
transported around the body. A large number of chemical
compounds can be put into aqueous solution.
2. Water is necessary for the chemical reactions that involve
hydrolysis (e.g.,enzymatic digestion of carbohydrates, pro-
teins and fats).
3. Water helps regulate body temperature. Water has a high
specific heat (specific heat = amount of heat necessary to
º
raise 1 g of water 1 C. Specific heat of water = 1). Large
changes in heat production can take place within an ani-
mal with very little change in body temperature. This
property also allows for heat to be circulated. Water has a Figure 5-2. Total biologic dose-response curve. This response
high latent heat of vaporization.Water helps regulate body curve spans intakes ranging from deficiency to adequacy to toxicity.
temperature when it is evaporated from the skin and res- The intakes at which these three phases reside, and the width of
piratory tract. Large amounts of heat are required to evap- the range between deficiency and toxicity vary widely among nutri-
orate small amounts of water; therefore, much heat can be ents. (Adapted from Underwood EJ, Mertz W. Introduction. In: Mertz
W, ed. Trace Elements in Human and Animal Nutrition, 5th ed. San
lost with little loss of water.
Diego, CA: Academic Press Inc, 1987; 1.)
4. Water provides shape and resilience to the body.
Significant negative water balance can result in clinical
dehydration. One manifestation of dehydration is loss of varying from 40 to more than 80% of the total.The percentage
skin elasticity. As a major constituent of body fluids, water of water in an animal’s body varies with species, condition and
helps lubricate the joints and eyes, provides protective age. Generally, lean body mass contains 70 to 80% water and 20
cushioning for the nervous system and aids in gas to 25% protein, whereas adipose tissue contains 10 to 15%
exchange in respiration by keeping the alveoli of the lungs water and 75 to 80% fat. Younger, leaner animal contain more
moist and expanded. body water. Conversely, fatter animals have lower body water
Water is one of the largest constituents of the animal body, content.