Stress - Lecture Flashcards

Why are purebred animals more prone to diseases?

Characterized by small numbers of founders, with strong selection for morphology, size, and colour.

• Leads to many health issues (this is basic genetics sorry)

Common dog purebred health issues

• Hip dysplasia

  • hip joint doesn’t develop properly

    • common in large breeds

      • German Shepherd

• Breathing problems

  • shortened snout has been bred on

  • Bulldogs

• Epilepsy

  • neurological condition more common in some purebreds

• Heart defects

  • more common in some purebreds

• Eye problems

  • Beagles prone to glaucoma

  • Pugs prone to eye issues to to facial structure

• Bloat

  • life-threatening condition often seen in deep-chested breeds

  • e.g. boxers

• Skin and ear issues

  • Infections due to folded ears

  • Bloodhounds

Common health issues in other purebred animals

• Persian cats

  • Brachycephaly

    • Flat faces cause lifelong breathing problems, chronic tear duct blockage, and dental misalignment

• Scottish fold cats

  • Ear fold

    • Causes painful disease that degrades joint cartilage throughout the entire body

• Broiler chickens

  • Rapid growth

    • Accelerated muscle growth causes skeletal lameness, leg deformities, sudden heart failure

• Domestic turkeys

  • Massive breast muscles

    • Selected for huge breasts, modern turkeys cannot reproduce naturally

• Dairy cows

  • High milk yield

    • Extreme milk production causes chronic udder inflammation (mastitis) and metabolic exhaustion

• Belgian blue cattle

  • double muscling

    • extreme muscle growth, frequently requires c-section for birthing due to the calves being too large

Explain why inter-species rules and intra-species rules do not overlap in regards to body size and life expectancy

• Bigger species live longer because they evolve slower metabolisms and have fewer natural predators

  • e.g. elephants outlive mice

• Smaller individuals live longer because extremely rapid growth in giant varieties causes severe cellular stress and accelerates biological ageing

Pain in horses

• Difficult to assess

• “Ridden Horse Pain Ethogram” developed with 24 behaviours indicating pain

  • Difficult when it is being ridden as the rider may affect the behaviour with reins, leg signals, body weight etc

  • Horse is taken away from the rest of the flock when ridden which makes it display other behaviours

Immune system in invertebrates vs vertebrates

• Invertebrates

  • Innate immunity

    • Provides immediate, non-specific protection from pathogens

    • e.g. skin, phagocytes

• Vertebrates

  • Innate immunity

  • Adaptive immunity

    • slower, antigen-specific response that develops memory

Antigen

Foreign substance that enters your body, e.g. bacteria, viruses, fungi, allergens, venom etc.

Antibodies

Attach to antigens to make it easier for immune cells to destroy the antigen.

Explain how the adaptive immune system works

Upon encountering a pathogen, a naive B cell migrates to a germinal centre to partner directly with T cells. This collaboration guides the B cell to differentiate into regulatory, short-lived, or specialised long-lived plasma cells. Ultimately, this teamwork yields memory B cells and plasma cells that produce targeted antibodies (IgG, IgA, IgE) for long-term immunity.

Explain how stress affects the immune system

• Cortisol decreases T-cell activity:

  • High levels of this glucocorticoid reduce the activation and multiplication of T-cells, which lowers defence against infections (B-cells are dependent on T-cells -> reduced antibody response) and reduces vaccine effectiveness.

• Adrenaline & Noradrenaline shift priority:

  • These hormones suppress the adaptive immune system (T-cells and B-cells) but boost innate immune cells (like macrophages) to handle immediate, physical threats

• Study in mice:

  • Acute stress in mice led to increased norepinephrine levels, which enhanced macrophage activity but concurrently suppressed the activation of T cells.

  • In contrast, chronic stress in mice led to decreased B cell function and impaired antibody responses, emphasizing the long-term impact of stress on humoral immunity.

Why (ultimate) does stress affect the immune system?

• To save energy

  • Redirects energy-heavy tasks like building T/B-cells so vital glucose and oxygen can be transferred to the muscles to fight/flight instead

• To survive the minute

  • Long-term immunity toward a future illness is useless if you get caught by a predator right now

• To heal wounds fast

  • Focus shift to the innate immune system, sending white blood cells (a type of phagocyte) directly to the skin to quickly patch up physical injuries

Acute stress and immune activation

Acute stress often leads to a temporary enhancement of immune function, known as the “stress-induced immune response”, preparing the body to respond effectively to immediate threats. It facilitates the mobilization of immune cells and increases the production of pro-inflammatory cytokines.

Acute stress can increase the number of certain immune cells circulating

in the blood, making them more available to travel to a site of injury or

infection.

Chronic stress and immune dysregulation

Chronic stress can lead to decreased T and B

lymphocyte proliferation, impairing/suppressing the

adaptive immune response and increasing susceptibility

to infections.

Acute stress vs Chronic stress and the immune system

• Acute stress

  • Acute stress often leads to a temporary enhancement of immune function, known as the “stress-induced immune response”, preparing the body to respond effectively to immediate threats. It facilitates the mobilization of immune cells and increases the production of pro-inflammatory cytokines.

  • Acute stress can increase the number of certain immune cells circulating in the blood, making them more available to travel to a site of injury or infection.

• Chronic stress

  • Chronic stress can lead to decreased T and B lymphocyte proliferation, impairing/suppressing the adaptive immune response and increasing susceptibility to infections.

Social stress and the immune system

Farm animals exposed to social stressors have a reduced immune system.

• Stocking density: increases the risk of infection spread; easier for pathogens to survive

Individual differences in stress/immune systems

• E.g. in a study of cows:

  • Animals were categorized according to low or high cort levels after having experienced social isolation

  • only high-cort responders later developed a fever when undergoing an intramammary endotoxin challenge

• Similar in pigs:

  • pigs categorized by effort in attempting escape from a restraint had differing changes in immune system following subsequent social isolation

Sickness behaviour

• Adaptive, energy-saving strategy that maximises fitness during a health crisis

• caused by the immune system, NOT the pathogens

  • shifts reproduction and growth toward immediate survival

    • cytokines (by the macrophages?) signal the brain to induce lethargy and anorexia to halt resource-heavy behaviours (e.g. foraging) to fuel immune defence and tissue repair

  • self-isolation to avoid predators and infection of conspecifics

Discuss how the microbiome affects the immune system

(Microbiome trains the immune system to distinguish between friend and foe)

• Microbiome interacts with both innate and adaptive immune systems through microbial components and metabolites.

  • crucial for developing immune responses

  • disruption by factors (e.g. antibiotics, stress) can contribute to inflammatory and autoimmune diseases

How does stress affect the microbiome?

• In mice, stress changes the composition of the microbiome

  • not clear how

• Gastrointestinal disorders worsen during stress

Explain the microbiota-gut-brain axis

• Gut microbiome influences behaviour and “gut feelings” via microbiota-gut-brain axis

• Gut microbes affect mood, stress, and cognition by producing neurotransmitters, interacting with the immune system, and communicating via neural and hormonal pathways

1. Gut and brain send instant physical signals to each other

2. Intestinal cells release cytokines

3. The brain activates cortisol release to disrupt the gut

4. Gut bacteria produce fatty acids that protect the brain

Give examples of how the microbiome can affect behaviour

• In mice, when given faecal microbiota transplantation, the behavioural traits of the recipients became more like those of the donor

• Behavioural effects have been traced to specific subsets of the microbiota

• Evidence suggests that Lactobacillus and Bifidobacterium (both probiotics) alleviate anxiety and depressive-like symptoms

Hypothesis regarding the behavioural effect of microbiomes

• Microbiota-driven alterations of host behaviour have lead to the hypothesis that some symbionts manipulate the host for their own ends

• e.g. microorganisms may make animals more sociable, and even altruistic, in order to increase host contacts and enhance their transmission

Microbiome and the HPA axis

Germ-free mice have poorly developed immune systems

• exhibit elevated levels of ACTH and corticosterone (e.g. stronger HPA responses) when subjected to stressors

  • dysregulation of the HPA axis

Discuss how domestication has influenced the gut microbiome

• E.g. dogs/wolves began eating human food as well that are rich in starch

  • made them into calmer dogs (helped the domestication process)

Urbanization effect on animal health

• Negative effect due to exposure to toxins, parasites, stress from habitat fragmentation and novel stressors like light and noise pollution

• E.g. long-term data in house sparrows found nests affected by noise pollution had fewer young, lower body mass of offspring, and fewer recruits, even during cross-fostering

  • females also provided less food to the younglings in noisy areas

• E.g. meta-analysis showed negative relationship between urbanization and health

Effects of stress depends on

• Intensity of the stressor

• Duration of the stressor

• Timing of the stress exposure

  • brain is particularly sensitive to stress early and late in life

  • early life has a larger welfare impact on domesticated animals (few actually make it to old age)

  • stress experienced during critical early-life period can have long-lasting or permanent changes on the brain

Brain maturation involves multiple dynamic processes that are regulated by

• genetic factors

• environmental input    

  • e.g. visual lateralization in chickens

    • if the chick/egg is incubated in darkness, the brain does not become lateralized

Developmental processes in the early postnatal brain

• Axonal and dendritic growth

• Synaptic stabilisation

• Synaptic pruning

Epigenetics

= how our environment changes the gene expression

• heritable, but no actual changes in the DNA

Two specific phenomena of interest:

• Histone modification

  • how DNA wraps around histones (proteins)

• DNA methylation

  • Moves histones to prevent/allow gene expression (on/off switch basically)

    • can be permanent

E.g. by cross-fostering, scientists found out that anxious parents raise anxious kids, while caring mothers causes permanent changes in the genetically anxious kids to become more secure adults.

• Hippocampus is involved

• The different maternal cares caused differences in DNA methylation in brains of the offspring

Hippocampus

• Complex brain structure embedded deep into a temporal lobe

• Major role in learning and memory

Discuss how early care of offspring can affect the offspring in adult life

(Using a cross-fostering experiment on rats):

• Type of maternal care caused distinctive differences in DNA methylation in brains of offspring

  • Differences still present in adult offspring, affecting their stress responses

    • Corticosterone increase after physical restraint was less pronounced in adult offspring of more caring mothers, which demonstrated long-lasting effects of the epigenetic modifications

• Female offspring having received more licking and grooming by their mother also behaved similarly towards their own offspring

• Transgenerational effects may therefore remain for a long time by means of a reinstatement of the behavioural phenotype in every generation

Early life can be divided into:

• Prenatal period

  • Before birth/hatch

• Early postnatal

  • Right after birth/hatch

• Adolescence

  • Just before sexual maturity

Prenatal stress

• Mediated via mother (maternal stress)

  • a mother’s stress affects her daughter AND granddaughter

• Very sensitive period due to the complex and rapid development of the embryo

  • a LOT happens from day to day

• Effects on offspring:

  • Increased HPA-axis

  • Structural and functional changes in the limbic system and prefrontal cortex

  • Learning/memory deficit and increased anxiety levels

  • Decreased immune system

  • Lower birthweight (humans)

From when is the HPA-axis functional in chickens?

• From day 15 of incubation (21 days in total)

• Cort can be measured in the down-feathers of newly hatched chicks,

  • (but no cort in the egg yolk ??)

Discuss how CORT affects the reproductive system

• Glucocorticoids can influence the synthesis of gonadal steroids both by downregulation of the gonadotrophins and via direct effects on the testis and the ovaries

• Stress impacts the reproductive axis — the hypothalamus (to affect GnRH secretion) and the pituitary gland (to affect gonadotrophin secretion)

• Elevated plasma CORT levels lead to

  • reduced plasma/egg testosterone and progesterone concentrations

  • reduced yolk/egg mass

How is offspring (fetus) protected by the mother’s cort levels ?

• Mammalian fetus is partially protected from elevated cort exposure by placental 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2)

  • (11 beta-HSD2) plays a crucial role in converting hormonally active cortisol to inactive cortisone

• Extra embryonic membranes in birds eggs have same function as placenta in mammals

• 11β-HSD2 has been found in chicken oviduct/gonads

• In vitro studies on chicken yolk follicles - Yolk follicles degrades corticosterone to 20β-dihydrocorticosterone

Effect of prenatal stress on the adult chicken brain findings:

• Brain size not affected

• Brain region size not affected

• Neuronal density not affected

• Non-neural density reduced

Altricial vs precocial

• Altricial

  • Useless baby (underdeveloped)

• Precocial

  • Functional baby (developed)

How does stress during early postnatal period affect adults?

• E.g. rats who were separated earlier from mothers become more fearful

• E.g. cats who were weaned earlier tend to wool-suck more

Examples of early life stress in production systems

• Transport stress

• Nutrition stress

• Heat stress

• Mixing stress

• Antigen toxin stress

• Weaning stress

• Cold stress

• Crowding stress

Why is the adolescence period sensitive for stress?

• Large hormone alterations

  • HPA axis interacts with the HPG axis

• Large behavioural alterations

  • Brain maturation

State some hypotheses why animals are so sensitive to stress

• PAR hypothesis

  • Organism uses environmental cues during early life to forecast future conditions and permanently adjust to its long-term physiology

• Developmental-mismatch hypothesis

  • Early experiences shape the brain and behaviour

    • major differences in stressors between the early years of development and later life stages are mismatches that can cause diseases (both physically and mentally)

Abnormal behaviour

• Seen in captive animals, never in the wild (unless they are sick and the brain is affected)

• Often stem from normal behaviours

  • e.g. giraffes roll their tongues to grab leaves

    • abnormal behaviour: uses tongue movement on objects with no food, e.g. fences/bars

• Is either behaviour that

  • never occurs in nature (atypical)

  • abnormal in its occurrence, frequency, or intensity from the normal value

Define normal behaviour

• Species-specific

• Behaviour developed during evolutionary adaptation

• Any learnt behaviour that serves the function of promoting fitness

• Plays a role in facilitating homeostasis

  • E.g. birds huddling together for warmth, lion hunting for food

• May vary with season and age

  • e.g. hormones, daylight, temperature

Define abnormal repetitive behaviour

• Inappropriate, repetitive, and unvarying in goal or motor pattern

• Divided into

  • Stereotypies

    • Repeated body motion/position that lack any goal or function

    • e.g. pacing

  • Impulsive/Compulsive behaviours

    • Repetition of a behaviour that has a goal

    • e.g. feather plucking in parrots to the point of naked skin

• Often regarded as stress-coping mechanisms

• Different types of abnormal behaviour exists between species and within species

What triggers abnormal behaviour in the captive environment?

• Can be challenging to elucidate the trigger for abnormal behaviours

• e.g. stereotypic digging in gerbils (digging onto the glass)

  • in this case, behaviour was reduced by tunnels, not substrate

    • a mechanism for the gerbil to cope with the lack of tunnels

  • in this case, the abnormal behaviour was goal related

• e.g. pacing

  • performance more ”important” than the resource (despite often being linked with the need of large home ranges to hunt

  • The larger the difference between their normal home range and the size of the captive enclosure, the more the animals would engage in pacing.

  • behaviour related abnormal behaviour

• Occurrence of abnormal behaviour varies between individuals in the same environment

• Omnivores/herbivores mainly develop oral stereotypies due to the motivation to explore and seek food

  • if environment is kept barren/static, they can no longer explore or forage

• Abnormal behaviours can spread across a population

  • might be learnt socially

  • first individual who develops the abnormal behaviour might have had another trigger than the other individuals

Reasons why it is difficult to disentangle the underlying proximate causes of abnormal behaviours:

• Abnormal behaviours are hard to detect since they only take up a small portion of its time budget

• Can look at the intrinsic and extrinsic risk factors

Intrinsic risk factors

Some species are more likely to perform a specific abnormal behaviour. Also:

• Age

• Sex

• Temperament

• Clinical condition

Extrinsic risk factors

• Rearing history

• Social environment

• Physical environment

• Clinical, research, and husbandry procedures

  • may cause stress that turns into abnormal behaviours

Intrinsic vs extrinsic risk factors

• Intrinsic risk factors

  Some species are more likely to perform a specific abnormal behaviour. Also:

  • Age

  • Sex

  • Temperament

  • Clinical condition

• Extrinsic risk factors

  • Rearing history

  • Social environment

  • Physical environment

  • Clinical, research, and husbandry procedures

    • may cause stress that turns into abnormal behaviours

Give examples of abnormal behaviours and mention their risk factors

E.g. tail biting in pigs and feather plucking in chickens

• omnivores/herbivores mainly develop oral stereotypies due to the motivation to explore and seek food

  • Pigs spend up to half their waking time rooting and chewing in search of food

  • Red Junglefowl use more than 60% of their time pecking and exploring

  • in static, barren environments, pen mates are the only part of the environment that moves and change

• may develop into cannibalism

• Risk factors:

  • Lack of enrichment

  • Wrong nutrition

  • Learned behaviour

  • Genetics

  • Sex

  • etc

Ultimate causes behind abnormal behaviours

• Reproductive fitness is affected by humans

• Explanations therefore tend to be proximate

• Function of the behaviours may help us understand the welfare implications

  • e.g. specific environmental deficiencies

Stereotypic behaviours in (stabled) horses

• E.g. crib biting, wind sucking, box walking, weaving

  • wind sucking extremely damaging to horses! Swallowing air can be deadly to them

  • bed eating may represent redirection of grazing behaviour in stabled horses without access to a high-fibre forage

  • attempts for the stabled horse to gain control over its environment, e.g. crib biting may reduce arousal

• Less common in horses with access to large yards and visual and tactile contact with a large number of other horses

  • if a horse is more alone, it becomes more stressful

    • it is a natural instinct to be in herds despite being safe in a stable

• Stable horses are also often fed with high-energy low-fibre concentrates

  • risk for stereotypies

Prevention of stereotypic behaviours (not the cause itself) can lead to:

• The animal persisting with the activity but in a modified form

• Prevention can be distressing for the animal (e.g. increased heart rate and cortisol activity)

Is stereotypic behaviour an adaptive response?

• Although these responses may be an attempt to cope with environmental deficiencies, their continued expression does not mean they are wholly successful compared with related activities that might be performed in the wild, and that the horse's welfare is ensured.

• Thus far, the evidence that stereotypic activities represent an adaptive response is appealing but circumstantial, as studies have tended to investigate horses once the behaviours have become established rather than during their development. More convincing evidence would be provided by prospective studies that followed the development of the activity and associated changes in physiological state.

Normal aggression vs abnormal aggression

Aggression depends on

• environment

  • e.g. resource-rich area vs resource-limited

• social context

  • e.g. is the animal fighting a more or less dominant individual

• daily/seasonal variations

Conflicts are settled according to certain rules (at least in rodents)

• e.g.

  • benefits: resources, shelter, mating

  • cons: injury, predation, energy cost

• aggression is kept below a certain limit to minimize injuries and excessive energy loss

• bites are targeted toward body parts that lack vital organs and are less exposed to infections (back and flanks in rodents)

• reproductively valuable individuals are largely protected from attacks by males

If these rules are ignored, the behaviour is abnormal

• e.g.

  • no warning/signalling to allow withdrawal

Normal aggressions are short-lived to quickly determine who the strongest is

• once this is established, there is no need to fight anymore due to the cons of conflict

It is abnormal

• mismatch between provocation and response

  • characteristic to many aggression-related pathologies from brain lesion to mental disorders (especially in humans)

• disregard of species-specific rules

  • e.g. males attacking females or vulnerable targets

• insensitivities toward the social signals of the opponent

  • e.g. sustaining attacks despite clear signs of submissiveness on the other side

The criteria proposed for differentiating normal from abnormal aggression in rodents

(A) Quantitatively excessive aggression

• Decreased latency to attack.

• Increased number of bites, persistent bursts of biting.

• Intense, tissue damaging attacks.

(B) Qualitatively changed attack patterns that imply severe injuries for opponents

• Deficient signalling of attack intentions by threats

• Bites targeted towards vulnerable body parts of opponents

• Disregarded appeasement signals

(C) Aggressive behaviour that involves excessive risks for the attacker on the short or the long term

• Aggression initiated in inappropriate settings

• Attacks on larger, potentially dangerous opponents.

• Harmful attacks on pups and females

(D) Dysfunctional aggression is persistent and is associated with other behavioural disturbances

• Attack pattern do not vanish on repeated exposure to opponents

• Altered sociability, anxiety- or depression-like behaviours, etc

“SAM system” stands for

Sympathoadrenal-medullary system

SAM-system/Fight-or-flight symptoms

• Rapid heart beat and breathing

  • Body requires more energy and oxygen to the body — increases blood flow

• Pale/Flushed skin

  • Blood to surface areas is reduced

  • Blood to muscles, brain, legs, and arms is increased

  • = may become pale as a response

    • face might also alternate between pale/flushed due to the blood rushing to your brain/head

• Dilated pupils

  • body becomes more aware of surroundings (better vision)

• Trembling

  • muscles become tense and primed for action

    • tension may result in trembling/shaking

SAM pathway

• Acute stressor (e.g. slipping on ice)

• Amygdala is mobilized

  • associating sensory signals with emotions associated with fight/flight (e.g. fear, anger)

  • sends distress signals to the hypothalamus

• Hypothalamus is alerted if the situation is appraised as potentially stressful or dangerous    

  • activates the sympathetic nervous system (SNS)

• SNS speeds up heart rate and blood pressure

  • activates pathways running to the adrenal medulla

• Adrenal medulla (centre of the adrenal glands) releases adrenaline into the bloodstream

• Adrenaline

  • boosts the supply of oxygen and glucose to help the body respond to stressors

  • stops non-emergency bodily functions (e.g. digestion)

• Noradrenaline raises physiological arousal (similar to adrenaline) and helps equip the person for fight-or-flight.

• Stress causes the brain (locus coeruleus) to send a signal via sympathetic neurons to the adrenal medulla. This releases adrenaline and noradrenalin into the blood, which gives us the classic fight-or-flight symptoms. Negative feedback ensures that the process is short-lasting

• All of this happens within seconds

Sympathetic nervous system

Prepares the body for intense physical activity (fight/flight)

How to measure SAM activity?

• Heart rate [beats/minute] & Heart rate variability

  • Implantable transmitters

  • Externally mounted non-invasive transmitters

• Pupil size

• Flushing

  • Thermal imaging — look at differences in blood flow within the individuals to see the activation of the SAM system

Heart rate variability

Measures specific changes in time (or variability) between successive heart beats

• If interval is relatively constant —> low HRV

  • HRV decreases during stress

• If interval changes —> high HRV

  • HRV increases during relaxing and recovering activities

Time between each beat is measured in [ms]

• is called an R-R Interval or Inter-beat Interval (IBI)

Natural variations in heart rate

• Varies naturally throughout the day within the same individual

  • Walking/Standing

  • Sleeping/Awake

• Varies between individuals

  • Measurement errors (e.g. how secure are the transmitters?)

  • Different physiologies/health (e.g. is one of the individuals sick at the moment? Inflammation causes higher heart rate)

What brain characteristics result in higher intelligence?

• Brain size (relative to body size)

  • consider this as the brains having better processing power

Domestication and its effect on brain size (domestication syndrome?)

• Absolute brain size remains the same

  • Relative brain size decreases (due to larger bodies, e.g. for production)

• Brain regression hypothesis:

  • Domesticated (less fearful) animals adaptively reduces the brain size in order to reallocate energy and resources to other traits, e.g. reproduction, production

• Brain size and body size are NOT tightly constrained genetically (in chickens)

  • body size can increase without leading to the same increase in the brain

• The cerebellum increases the most (proportionally) in domesticates

  • most neuron-dense brain region

  • important for being able to perform everyday voluntary tasks

  • involved in cognitive processing

• Argument that brain is smaller since domesticated animals don’t have to think about finding food, avoid predators etc

  • Counter-argument: still need social abilities etc so absolute brain size remains the same

Ways stress can affect the brain/cognitive abilities

• E.g. unpredictable light schedule in chickens

  • made it difficult to know when to sleep/perch, feed etc

  • needed more attempts to solve a spatial learning test than chickens in a 12:12 hour light schedule

Direct brain measures

• MRI (or similar)

  • can get good info but animals may need months of practice to lie still

• Electrodes

• Post-mortal brain measures

Tail-biting in pigs and gene expression

Some pigs are more prone than others to bite tails/receive bites

• 19 genes show a different expression patterns in neutral pigs compared to biters/receivers

  • These genes were associated with sociability (humans, mice), novelty seeking (humans), and production traits (pigs)

Explain how brain lateralization can be used as a welfare indicator

The left/right sides of the brain process information in different ways

• Left:

  • Well-established behaviours performed in non-stressful situations

• Right:

  • Responds to unexpected stimuli and controls escape and other emergency responses

E.g. cows use the left eye to look at novel, fear-inducing stimuli

• tells us how a novel stimuli is perceived by the cow

E.g. horses who strongly prefer viewing novel stimuli with their left eyes are more reactive than those with weaker left-eye preference or no preference

• informs us about their personality (reactive vs proactive)

E.g. toads show higher avoidance responses when perceived threat approached from the left side

• Teaches us that we can lower stress levels in toads by approaching from their right side

Brain lateralization in chicks

• Ability to search for food among pebbles with the right eye and scan for predators with the left eye

• Develops if the embryo’s right eye gets light exposure (left eye is obscured by its own body) for a few seconds/minutes a few days before hatching

• Non-lateralized chicks perform more distress calls when exposed to a predator

Cognitive abilities in chickens

• Can do math and geometry

• Can memorize 100 human faces and other chicken individuals

• Have unique personalities

• Use logic/complex social tactics

• Show self-control / Hold out for better rewards

• Have extensive “vocabulary”

Five Domains vs Five Freedoms

• Five Freedoms

  • Focuses on preventing bad things, e.g. pain, hunger

• Five Domains

  • Focuses on the animal’s mental state

  • Adds positive things, e.g. joy, choice

Human handling of farm animals

• Most common form of human handling

  • also mostly studied due to the economic costs of decreased production

• Negative handling, despite brief and regular

  • increases fear of humans and stress

  • reduces

    • growth

    • feed conversion efficency

    • reproduction

    • health

How does the physical handling of animals affect them?

• Rough handling affects their health negatively

  • e.g. shouting, hitting, approaching too quickly, or moving in unpredictable ways

  • Farm animals handled roughly associates this handling with ALL humans (observed in pigs, chicks, cattle)

    • This learned fear can have marked effect on the production

    • e.g. milk production, gentle vs aversive handling

• Gentle handling — compared to rough handling in poultry:

  • Increases egg production

  • Reduces injury

  • Increases resistance to E. coli infection

  • Improves feed efficiency and growth

• Note that also NO physical contact (just the presence itself) can lead to negative health effects

  • Especially prey animals, who may see us as predators

Can animals distinguish between different human individuals?

• Pigs

  • Does not always distinguish between different handlers/strangers

  • Tend to generalize the behaviour of one handler onto all handlers

  • Early handling of pigs lower their stress for future general handling

  • Reacts differently to different people (uncertain if this is due to different behaviour or not)

• Chicks

  • Generalize their habituation to the original handler to a similarly dressed stranger

  • Imprinting behaviour proves that they can distinguish between “mother” and other people

  • Reacts differently to different people (uncertain if this is due to different behaviour or not)

• Cattle

  • Early handling of cattle lower their stress for future general handling

  • Reacts differently to different people (uncertain if this is due to different behaviour or not)

Imprinting

Precocial birds (chicken, ducks, geese…) are genetically programmed to bond with the first moving object they see between 12-36 hours after hatching

Human-Animal Interactions are affected by the following factors in humans:

• Attitude

• Knowledge and experience

  • some keepers with long-term experience may have a more aversive behaviour

• Personality

  • patient, independent, and non-sociable may correlate with cows’ willingness to enter milking machines and reduced restlessness during milking

• Anxiety levels

  • human fear triggers immediate defensive responses in horses, causing them to avoid human interaction

• Gender

Effect of attitude on animal handling

• Pigs

  • Proportion of negative interactions initiated

  • Time taken for sows to approach handler (measure of fear)

  • Total litter size (measure of reproductive success)

• Cattle

  • Positive attitude correlates with positive handling, correlates with lower stress in the cows

HUEC

Behaviour(s) animal ONLY performs in the presence of humans

Tonic immobility

When flipping a chicken upside down, they may stay frozen due to a fearful response

• The longer in tonic immobility, the more fearful it is considered to be

One health

The integrated health of humans and animals (and environmental health)

• E.g. less fearful pigs is better welfare for both the pig and the handlers

Potential solutions to reduce negative interactions

• Increased contact with humans

  • Particularly during rearing

    • Can markedly decrease the level of fearfulness of the animals

• Appropriate posture and behaviour during contact

  • e.g. talking quietly, avoiding sudden movements, touching the animal at first approach

  • Use species-specific behaviours.

    • For example, the best places to touch animals could be determined by examining where animals groom each other.

• Improvement in handling facilities

  • leading to easier flow of animals, would greatly reduce the amount of rough handling farm animals receive, and would likely result in tamer and less fearful animals.

  • A learned fear of people as a result of necessary aversive treatment can be reduced if the person doing the treatment wears special coloured clothes.

• Consistency and familiarity

  • If negative interactions were randomly incorporated into a routine of mostly positive interactions, the animals showed virtually the same elevated level of fear as animals that received only negative interactions. Such effects on animal welfare may be due to a reduction in an animal’s sense of predictability and control

    • a study of Captive cheetahs showed that the regularity of husbandry routines was positively correlated with reproductive success.

Zoonotic diseases/zoonoses

• Diseases shared among animals and humans

Reverse zoonosis

Transfer of pathogens from humans to animals

How to measure welfare

E.g.

• Skin condition

  • Injuries/lesions = bad welfare

Define good animal welfare

It is an objective evaluation

• although there is no consensus on how to do it objectively

Once welfare is assessed, society can integrate these biological facts with moral views

Animal welfare refers to how well an animal is coping with the conditions in which it lives

• Depends on the individual level

Terminology for individual differences in behaviour

• Behavioural syndrome

  • Suite of correlated behaviours

  • Not necessarily studied under stress conditions

• Personality

  • In humans: Often includes emotional reactivity traits

  • In animals: Ignores emotional component

• Coping styles

  • Include both behavioural and physiological responses to an unfavourable environment and stress

Passive coping strategy

Not equal to “doing nothing”

• Includes enhanced SAM and HPA activity to the same degree as more active coping strategies

Coping strategy vs emotionality

• Coping strategy: Type of response an animal makes (how it reacts)

• Emotionality: Level of responsiveness to challenge

Main coping styles

• Reactive

• Proactive

• Passive

• Ambivalent

Tonic immobility

• Last defensive resort

• Reflexive and involuntary reaction

  • Elicited under the perception of overwhelming danger

• Reversible, profound motor inhibition

Coping style, fearfulness, and sociality are separate traits that are not necessarily linked

Robustness vs resilience

• Robustness

  • How much you can take before you fall down

• Resilience

  • How long does it take you to stand up again

Variables to measure for assessing animal welfare

• “Biological fitness” variables

  • Life expectancy and reproductive output

• Physiological variables

  • Increased HPA activity

    • e.g. saliva in dogs

    • Note that the data collection itself may be stressful for the animal

    • IRT

  • Increase in heart rate, body surface temperature etc may be caused by both positive and negative experience, thus making them hard to interpret sometimes

• Behavioural variables

  • Account for both internal and external conditions

  • eg.

    • Preference test

• Genetics

  • Telomeres

Poor animal welfare can be the result of

• Ill-health

• Injury

• Disease

• Stress

• Frustration

• Boredom

• Loneliness

• Grief

Saliva sampling pros/cons

• Less invasive than blood samples —> animal less stressed

• Large inter-and intra-individual variation in salivary cort levels

• Food particles can interfere with immunoassays

• Still somewhat invasive — some dogs still don’t want the chew the stick

Fur/feather sampling pros/cons

• Measures long-term stress

• Variability in cort can be smaller in feathers than plasma

  • Potential error is larger when measuring cort in feathers

• May also suffer from extraction bias + feather type/location —> speed of growth

Heart rate can be used as a measurement of welfare in the following circumstances:

• Assessing stress and well-being under various housing and management conditions

• Evaluating pathological conditions, training, and fitness levels (mainly horses)

Surface body temperature- Infrared thermography (IRT)

• Non-invasive technique for measuring surface body temperature alterations related to stress, emotions, and pathologies

• Acute physical and psychological stress and emotional arousal trigger a sympathetically mediated cutaneous vasoconstriction, causing a rapid drop in skin temperature

  • accompanied by a rise in core temperature, followed by a subsequent vasodilation in order to dissipate excess heat

    • Results in a post-stressor rise in peripheral temperature