13 - Measuring Animal Welfare And Stress

Front 1

Type 1 animal welfare concept

Back 1

Single attribute that can be directly measured

Front 2

Type 2 animal welfare concept

Back 2

Single attribute that cannot be measured directly but which can be estimated by combining contributing variables

example: measuring the weight of sun-bathers that would make a balcony collapse - need to objectively estimate design of structure, thickness of beams

Front 3

Type 3 animal welfare concept

Back 3

A trait involving multiple attributes linked by some commonality of function

example: measuring safety of a building - level of toxins in paint, fire escapes → common function is safety

Front 4

Why is animal welfare not a type 1 concept?

Back 4

For example, longevity:

-Single, measurable attribute

-Indirect indicator of quality of life (suggests most biological needs are met)

- BUT living longer does not mean a better quality of life (prisoners may live longer than owners of small aircraft)

Front 5

Why is animal welfare not a type 2 concept?

Back 5

- Integrating various attributes

- Can objectively measure things like stress, productivity, health, behaviour

- BUT: we do not know the objective correct weighting of the attributes

Front 6

Why is animal welfare a type 3 concept?

Back 6

- Different attributes measured objectively with common link (quality of life of animals)

- Interpretation of results involves values

- Scientific findings will not eliminate value based differences

- Animal welfare cannot be measured directly only assessed in a manner similar to safety or health

Front 7

Animal Welfare definition (short):

Back 7

- How an animal copes with the conditions it lives in

- The state of the animal

Front 8

Stress

Back 8

Denotes a real or perceived perturbation to an organisms physiological homeostasis or phsycological well-being (NAC, 2008)

Front 9

Claude Bernard on stress

Back 9

1878

Maintenance of a constant internal state in a constantly changing external environment

Front 10

Walter Cannon on stress

Back 10

1929

-Termed 'homeostasis'

- flight or fight response

- sympatho-adrenal system

Front 11

Hans Selye on stress

Back 11

1950

- Generalized stress response

- Hypothalamic-pituitary-adrenal response

Front 12

Moberg's definition of stress

Back 12

The biological response elicited when an individual perceives a threat to its homeostasis (2000)

Front 13

What is a stressor

Back 13

A "threat" - includes external events or internal factors including pain

Front 14

Homeostasis

Back 14

The tendency of a system, especially the physiological system of higher animals, to maintain internal stability, owing to the coordinated response of its parts to any situation or stimulus that would tend to disturb its normal condition or function

Front 15

How are stress and distress different?

Back 15

A term that helps differentiate between a non-threatening stress response and a biological state where the stress response has a deleterious effect on the individual's welfare (Moberg, 2000)

i.e. stress may not be a bad thing, but once it turns to distress then it is a bad thing

Front 16

Carstens and Moberg definition of distress

Back 16

An aversive, negative state in which coping and adaptation processes fail to return an organism to physiological and/or psychological homeostasis (2000)

Front 17

Definition of Suffering

Back 17

Negative emotional state associated with distress: can be due to adverse physical or psychological circumstances and is moderated by the cognitive capacity and experiences of the individual (NHMRC, 2008)

- capacity for sentience and role of feelings and emotions in experience

Front 18

Model of stress and distress

Back 18

Front 19

What are the 4 major biological responses to stress?

Back 19

- Behaviour

- Neuroendocrine system

- Autonomic nervous system

- Immune system

Front 20

Behaviour as a biological response to stress

Back 20

- First line of defense

- withdraw, fight or flight, freeze

Front 21

How is behaviour different in animals in response to stress?

Back 21

- Modified by species, environment, pain intensity, learning etc

- Variable response by same species to same stimulus (naive animal will be more stressed or animal with bad experiences will be more stressed)

- behaviour options can be limited in some environments

Front 22

2 major physiological indicators of stress

Back 22

Cortisol and Norepinephrine

Front 23

Autonomic nervous system as a biological response to stress

Back 23

- short term

- fight or flight

- quick physiological adjustment

- learning and memory may be improved

Front 24

How can we easily measure ANS response?

Back 24

It is very quick and difficult to measure

- one technique that has been used is to measure eye temperature: temp decreases then increases very quickly

Front 25

ANS Physiological response

Back 25

Hypothalamus → (direct neural connection with) Adrenal medulla (not cortex!)

Adrenal medulla:

- Increase in HR

- Vessel dilation and constriction (these with HR redirect blood to flow to brain and skeletal muscle)

- Facilitation of activation of other stress hormones (e.g. cortisol)

- Stimulation of gluconeogenesis and lypolysis

Front 26

Neuroendocrine system as biological response to stress

Back 26

HPA Axis = Hypothalamic-pituitary-adrenal

- long lasting effects on body

- all biological functions affected by stress are regulated by pituitary hormones

Front 27

Hormones related to stress:

Back 27

In response to stress, see increase in:

- cortisol

- corticosterone

- prolactin

- somatotropin

- thyroid stimulating hormone

- gonadotropins (LH and FSH)

Front 28

Cortisol stress response pathway

Back 28

Based on blood flow, slower than ANS, easier to see response and measure it

Hypothalamus perceives a stress

↓ (CRF) corticotrophiin releasing factor)

Anterior pituitary

↓ (ACTH) Adrenocorticotrophin hormone

Adrenal (cortex)

↓ (cortisol) glucocorticoids

Systemic tissues

Front 29

What does increased Cortisol do in systemic tissues?

Back 29

Redirecting nutrients:

- Inhibition of gonadotrophins (reproduction)

- Suppression of growth hormone (growth)

- enhanced glucose production for immediate needs

Preventing autoimmunity:

- suppression of T-cell activity (immune function)

Front 30

Issues with measuring cortisol levels:

Back 30

How much of a rise in cortisol is important?

Is the animal actually in distress (vs stress)?

Is the response disrupting normal processes?

Is the response effective?

Front 31

Immune system as a biological response to stress

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- modified by other systems (HPA)

- cytokines communicate between nervous system and immune system

- can measure immune competence to look at disease components of stress

Front 32

Short term stress vs Prolonged stress

Back 32

Front 33

Challenges to measuring stress:

Back 33

- Experiments actually require you to stress the animals

- All 4 systems used in response to stress but not all used to defend homeostasis

- different stressors elicit different types of biological responses

- need specific measures for each stressor for each system

Front 34

Moberg's greatest challenge to measuring stress:

Back 34

Interanimal variation in the stress response is the greatest problem in measuring stress (Moberg, 1985)

System used, and to what extent, is influenced by a variety of factors or modifiers

Front 35

Modifiers of stress response

Back 35

Experience

Genetics

Age

Physiological state

Season

Front 36

Stress pathway with Modifiers

Back 36

Front 37

So what should we focus on when trying to measure stress?

Back 37

Changes in biological function

How biological defenses impact the animal

Front 38

When does stress become a threat?

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"Stress becomes a threat only when the stress response is of such a magnitude that... it is sufficient to endanger the general well-being of the animal" (Moberg, 1985)

Front 39

Animal Welfare vs. Stress level graph

Back 39

If an animal has mechanisms available to deal with the stress (can adapt), it is okay.

Once it cannot cope, it is in distress

Front 40

Moberg's stress model

Back 40

Animal has a reserve of energy to deal with stress

Stress will decrease that reserve

Recovers to having a full reserve

Front 41

Moberg's distress model

Back 41

Insufficient reserves to deal with the stress = shift resources away from other biological functions such as growth or reproduction

Animal has entered prepathological-pathological state and are experiencing distress

Front 42

Acute distress vs Chronic distress

Back 42

Acute:

- short duration with large biological costs (e.g. disrupt ovulation or retards growth)

Chronic:

- same acute stressor over time (environment, heat, cold)

- summation of several stressors

Front 43

Summation of a stressor

Back 43

Front 44

Summation of multiple stressors

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example: calf being weaned and being moved to a new property

Front 45

Subclinical Stressors

Back 45

A type of chronic stress

- by itself does not effect function, but makes you vulnerable to effects of another stressor

(it is an underlying stress)

example: getting sick during exams

Front 46

Threat of subclinical stress graph

Back 46

Front 47

Potential stressors associated with traditional weaning of calves

Back 47

1. age at weaning is younger than natural age

2. new social environment

- absence of adults

- mixing of unfamiliar animals

- formation of new social hierarchy

3. physical separation of mother and calf

4. premature end of lactation (even though milk is still available)

5. transportation

6. new location

7. new diet

(Stookey, 2011)

Front 48

How does weaning negatively affect calves?

Back 48

- Creates immuno-compromised individuals

- More calves treated for disease and health issues immediately post-weaning than any other time

- Visible and overt signs of distress that last 3-5 days

- noticeable set back in performance (shutting down of growth hormone response)