Hunger and thirst

1
Hunger and thirst

• Adroaldo J. Zanella
• ANS 305

2
Introduction

• Freedom from hunger and thirst features as the
  first requirement that has to be satisfied in
  animal welfare codes/laws in many parts of the
  world.
• Extreme
• Mild deprivation

3
Background

• Extreme nutrient and water deprivation causes
  death.
• Failure to satisfy the animals requirement for
  essential nutrients leads to illness, poor
  performance and death.

4
Background

• Mild deprivation of water and nutrients has
  little effect on health and vigor.
• Ad libitum feeding of animals may lead to
  increase incidence of disease and poor
  reproductive performance.

5
Hunger feeding motivation

• The state of the animal in which it is stimulate
  to eat
• Nutritional properties of the food
• Physiological state of the animal
• External factors

6
Problems I

• Animals need to be hungry or thirsty in order to
  eat or drink.
• Aristotelian concept of telos
• All animals desire or strive to reach the
  functional end for which they were designed.

7
Problems II

• A) Malnourished conditions are limiting by being
  inappropriately balanced in relation to the
  animals requirements
• B) Undernourished conditions are limiting by
  being insufficient in relation to the animals
  requirements
• A B

8
Conditions

• Harsh environments
• Hot temperatures
• Competitive environment
• Lack of feeder and drinker space
• Inadequate drinker feeder design

9
Eating behavior

• Sensory cues
• Nutrients in the diet
• Hormonal factors

10
Feeding strategies

• Decision making processes are often overlooked.
• Pigs are capable of balancing their diets
• Food avoidance is common in many species
• Grazers will not eat in a random fashion.
• Plant chemicals
• Feces
• Nutritional contend

11
Feeding patterns

• Cows may graze from 4-14 h day and bite rates may
  vary from 40-80 minute.
• Periods of high ingestive intake
• Shortly prior to sunrise
• Mid-morning
• Early afternoon
• Near dusk

12
Feeding patterns

• Horse grazing behavior is affected by
• Early experience
• Quality of the pasture
• Social facilitation
• Temperature

13
Feeding patterns

• Eating behavior in pigs is affected by
• Social hierarchy
• Food quality
• Temperature
• Age
• Genetic background

14
Measurements

• A) Monitor food intake, rate of eating time
  spent in food-directed activity.
• B) Animals response to operant methodologies
  (e.g. the animal needs to work.
• C) Trade food acquisition with aversive stimulus.

15
Sources of malnutrition

• Unintentional
• Poorly balanced diets
• Intentional
• Veal calves are sometimes fed on liquid diet
  deficient in iron.

16
Sources of undernutrition

• Intentional
• Quantitative restriction
• Sows boars (60)
• Broiler breeders (25)
• Qualitative restriction
• Sows boars
• Ruminants

17
Sources of undernutrition

• Unintentional
• Negative energy balance (poor grazing conditions)
• Restrictions imposed by other group members
• High temperature
• Amount eaten
• Feeding pattern

18
Thirst

• Definition It is a subjective sensation aroused
  by lack of water (Rolls Rolls, 1982)
• Physiological state
• Diet
• Temperature
• Access to water
• Water quality

19
Waternutrient

• Adjustment of body temperature.
• Maintenance of mineral homeostasis.
• Excretion of end products of digestion anti
  nutritional factors.
• Achievement of satiety.
• Satisfaction of behavioral drives

20
Secondary drinking

• Hunger induced
• Schedule-induced polydipsia

21
Measurement

• A) Monitor water intake, rate of drinking time
  spent in drinking-directed activity.
• B) Animals response to operant methodologies
  (e.g. the animal needs to work.
• C) Trade water acquisition with aversive
  stimulus.

22
Water restriction

• Intentional
• Liquid wet feeding (pigs)
• Restricted to periods (broilers pigs)
• Premarin farms

23
Water restriction

• Unintentional
• Blocked pipes
• Inadequate flow rates
• Drinker design
• Water quality
• Social competition

24
Welfare problems

• Sheep will walk more than 25 km (16 miles) a day
  foraging
• Free range sows will spent over 50 of their time
  foraging

25
Welfare problems

• Expression of foraging behavior
• Failure to meet requirements (stress)
• Secondary illness associated with nutrient
  (including water) deprivation

26
Behavioral problems

• Abnormal behaviors
• Tail biting
• Wool-stripping
• Redirected behaviors
• Activity levels
• Exploratory behavior
• Food related stereotypies
• Sham-chewing