Chapter 6 Study Questions

Question 1

describe the importance of water to life

Answer 1

life could not be sustained without water – the absences of water could cause death faster than absences of any other nutrient

Question 2

what portion of the body mass is water? molecules?

Answer 2

1/2 to 2/3 of body mass in adult animals is water & up to 90% in newborn animals

99% of the body is molecules

Question 3

what are the 2 basic functions of water in the body?

Answer 3

• aids in body metabolism

- temperature regulation

Question 4

what are the 4 important overall functions of water in body metabolism? explain.

Answer 4

• water is a solvent: most cellular protoplasms/cytoplasms is a mixture of colloids & crystalloids in water
• water is a transport medium: medium for transportation of semisolid digesta in the GI tract, blood, tissue fluids, cells & secretions & in urine & sweat
• water is a dilutent: provides dilution of cell contents & body fluids so free chemical movement can occur w/in cells & in fluids & GI tract
• water fxns in hydrolysis & oxidation: in hydrolysis, water is a substrate in the reaction & in oxidation it is a product

Question 5

what is metabolic water?

Answer 5

metabolic water is water of oxidation

Question 6

what chemical component yields the most metabolic water upon hydrolysis?

Answer 6

the metabolic water/gram is higher in fat

Question 7

which nutrient compound supplies the most net metabolic water?

Answer 7

Carbohydrates

Question 8

why don’t hibernating animals need to drink water?

Answer 8

the metabolic & preformed water metabolized is enough to sustain normal functions

Question 9

what are the 3 properties of water that allow it to have a marked effect on temperature regulation?

Answer 9

• high specific heat index
• high thermal conductivity
• high latent heat of vaporization

Question 10

how can an animal increase heat loss through its lungs?

Answer 10

the lungs have a large evaporative surface area.

Question 11

can you think of an environmental situation in which evaporative cooling would not be very efficient & one where it would be highly efficient?

Answer 11

evaporative cooling would be less efficient in humid environments & dry environments it would be very efficient.

Question 12

how many calories are lost from the body by evaporating 5 grams of water?

Answer 12

1 gram of water requires 580 calories of heat so…

580 (5 grams) = 2900 calories

Question 13

how does the body prevent itself from having large changes in temperature?

Answer 13

the body has a great capacity to store heat — this prevents sudden temperature changes

Question 14

how is water’s thermal conductivity useful in dissipating body heat?

Answer 14

evaporation of body water

Question 15

where is water absorbed in the digestive tract?

Answer 15

most sections of the GI tract:

- ruminants: rumen & omasum

Question 16

what are 5 sources of water to an animal?

Answer 16

• drinking water
• water in or on feed
• metabolic water
• water liberated from metabolic reactions
• preforms of water associated w/ body tissues (catabolized during a negative energy state)

Question 17

what types of factors determine the relative importance of these to a specific animal?

Answer 17

diet, habitat & the ability to conserve body water

Question 18

compare the water needs of a desert rat to that of a producing livestock.

Answer 18

desert rat: will not require drinking water except in rare occasions
livestock: require copious amounts of drinking water when producing at a high level, especially when heat stressed

Question 19

why do you think dairy cows drink so much more water than beef cows?

Answer 19

they are constantly lactating (producing milk) & milk is made mostly of water

Question 20

is the water in feed an important contributor to livestock water needs? if so, how important?

Answer 20

forage = 5-7% water
hay = 90% water
young lush vegetation = 90% water

the precipitation & dew on ingested feed may account for a very substantial amount of water consumption

Question 21

describe one (or more) situations where a perfectly normal animal might not need to drink water

Answer 21

• hibernating animals
• foraging animals
• desert animals
• less active animals

Question 22

describe the methods of water loss from the body in detail, but no great detail than the course guide.

Answer 22

• expired water from lungs
• vaporization from the skin
• water lost in feces
• water lost in urine

Question 23

why is it difficult to delineate the water requirements of an animal?

Answer 23

b/c numerous dietary & environmental factors affect water absorption & excretion — water is important in regulation of body temperature

Question 24

what is the relationship between dry matter consumption & water consumption as long as the animal is not in heat stress?

Answer 24

water consumption is linearly related to heat production when the animal is not in heat stress

Question 25

describe how heat stress can affect water needs for animals. give a concrete example.

Answer 25

heat stress can cause a decrease in feed consumption & an increase in water consumption greatly.

i.e cattle at 40F, the water consumption per unit of dry matter consumption is at 0.35 gal/lb. vs. at 100F, the water consumption per unit of dry matter is at 1.9 gal/lb.

Question 26

what happens to water consumption in relation to water need on lush pastures?

Answer 26

there is a higher water consumption than needed when the forage is lush with high water content.

Question 27

how does protein intake affect water intake?

Answer 27

protein increases water requirements b/c of urea that is toxic & must be diluted to prevent it from damaging the kidney

Question 28

how does urea consumption affect urine volume?

Answer 28

urea requires a good deal of water for excretion. uric acid requires very little water so poultry species don’t have volumous urine

Question 29

milk is mostly water. why do nursing animals need more water?

Answer 29

the high content of protein in milk results in high obligatory urinary water loss & w/out additional water performance will be reduced

Question 30

how does fat consumption affect water intake?

Answer 30

increase intake of fat will also cause an increase in water intake

Question 31

what is the effect of salt consumption on water consumption & excretion?

Answer 31

salt increases consumption & excretion of water greatly

Question 32

generally speaking, how much water do animals need per quantity of dry feed consumed?

Answer 32

2-5 kg H2O/kg dry feed consumed

Question 33

what is the normal ration of water consumption to dry matter consumption for cattle? sheep? why do cattle need more?

Answer 33

cattle: 4:1 — need more b/c they aren’t as efficient at storing water
sheep: 5:1

Question 34

how does the water consumption of birds compare to mammals?

Answer 34

birds require less water consumption mammals

Question 35

how does young vs. adult affect for how much water is required?

Answer 35

young animals require more water per unit of body weight than adults

Question 36

how does activity affect how much water is required?

Answer 36

nervous animals will consume more water than less active ones

Question 37

how does milk production affect water consumption in cattle?

Answer 37

water consumption will be increased by milk production

Question 38

is there a valid reason for not allowing an animal unlimited access to water?

Answer 38

calves: death may result due to large amounts of water suddenly ingested due to kidneys slow adaptation to sudden high water load.