Blessed are those who hunger and thirst for righteousness, for they will be filled.
Hunger and thirst Adroaldo J. Zanella ANS 305. Introduction 4 Freedom from hunger and thirst...
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Transcript of Hunger and thirst Adroaldo J. Zanella ANS 305. Introduction 4 Freedom from hunger and thirst...
Hunger and thirst
Adroaldo J. Zanella
ANS 305
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
Background
Extreme nutrient and water deprivation causes death.
Failure to satisfy the animal’s requirement for essential nutrients leads to illness, poor performance and death.
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.
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
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”.
Problems II
A) Malnourished: conditions are limiting by being inappropriately balanced in relation to the animal’s requirements
B) Undernourished: conditions are limiting by being insufficient in relation to the animal’s requirements
A & B
Conditions
Harsh environments Hot temperatures Competitive environment Lack of feeder and drinker space Inadequate drinker & feeder design
Eating behavior
Sensory cues Nutrients in the diet Hormonal factors
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
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
Feeding patterns
Horse grazing behavior is affected by– Early experience– Quality of the pasture– Social facilitation– Temperature
Feeding patterns
Eating behavior in pigs is affected by:– Social hierarchy– Food quality– Temperature– Age– Genetic background
Measurements
A) Monitor food intake, rate of eating & time spent in food-directed activity.
B) Animal’s response to operant methodologies (e.g. the animal needs to work.
C) Trade food acquisition with aversive stimulus.
Sources of malnutrition
Unintentional:– Poorly balanced diets
Intentional– Veal calves are sometimes fed on
liquid diet deficient in iron.
Sources of undernutrition
Intentional:– Quantitative restriction
• Sows & boars (60%)
• Broiler breeders (25%)
– Qualitative restriction• Sows & boars
• Ruminants
Sources of undernutrition
Unintentional– Negative energy balance (poor
grazing conditions)– Restrictions imposed by other
group members– High temperature
• Amount eaten
• Feeding pattern
Thirst
Definition: It is a subjective sensation aroused by lack of water (Rolls & Rolls, 1982)– Physiological state– Diet– Temperature– Access to water– Water quality
Water=nutrient Adjustment of body temperature. Maintenance of mineral
homeostasis. Excretion of end products of
digestion & anti nutritional factors. Achievement of satiety. Satisfaction of behavioral drives
Secondary drinking
Hunger induced Schedule-induced polydipsia
Measurement
A) Monitor water intake, rate of drinking & time spent in drinking-directed activity.
B) Animal’s response to operant methodologies (e.g. the animal needs to work.
C) Trade water acquisition with aversive stimulus.
Water restriction
Intentional– Liquid & wet feeding (pigs)– Restricted to periods (broilers &
pigs)– Premarin farms
Water restriction
Unintentional– Blocked pipes– Inadequate flow rates– Drinker design– Water quality– Social competition
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
Welfare problems
Expression of foraging behavior Failure to meet requirements (stress) Secondary illness associated with
nutrient (including water) deprivation
Behavioral problems
Abnormal behaviors– Tail biting– Wool-stripping
Redirected behaviors– Activity levels– Exploratory behavior
Food related stereotypies– Sham-chewing