Assessing Animal Welfare: Physiological Responses

assessing animal welfare→ physiological measures

The relationship between welfare and the physiological responses.

→ STRESS RESPONSE

• Chronic stress and welfare

• How measures of stress response may be used in the

assessment of welfare

→ IMMUNE RESPONSES

→ NEUROBIOLOGICAL RESPONSES

→ METABOLIC RESPONSES

• environment/resources → brain evaluates → body responds→ animal adapts and survives

the adaptive process

→ Homeostasis: internal equilibrium (e.g., maintain blood pH at 7.35−7.45)

→ Allostasis: the process of achieving stability (homeostasis) through physiological and behavioral changes (e.g., pregnancy, lactation); proposed by Sterling and Eyer (1988) to describe an additional process of reestablishing homeostasis.

→ “The welfare of an animal is its state as regards its attempts to cope with its environment”

stress

→ The effect of physical, physiological, or emotional factors that induce an alteration in the animal’s homeostasis or adaptive state leads to stress.

→ “Stress is an environmental effect on an individual which over-taxes its control systems and results in adverse consequences, eventually reduced fitness.”

→ Stress is a natural event

→ Duration of the consequent effects: transitory (acute) or

long-term (chronic) stress

is stress a negative emotion?

• Stress can be defined as the degree to which you feel overwhelmed or unable to cope as a result of pressures that are unmanageable (Mental Health Foundation, UK, 2021)

• Findings from previous studies have shown that psychological stress responses often include negative emotions. In other words, people experience a complex array of negative emotions (e.g., depression, anxiety, anger) and distress during real-life stressful events (Du et al, 2018)

• In terms of the relationship between stress and negative emotions, researchers have reached a consensus that they are closely associated with each other

events that precipitate stress: stressors

→ Coping mechanisms or adaptive changes:

– behavioral reactions

– activation of the sympathetic nervous system and adrenal medulla

– secretion of stress hormones

– mobilization of the immune system

→ “Stress response”: behavioral or physiological mechanisms to counter the perturbation

the stress response

→ Autonomic nervous system

• sympathetic (adrenaline, noradrenaline)

• parasympathetic (acetylcholine)

→ Hypothalamus-pituitary-adrenal (HPA) axis

• W.B. Cannon: “Fight or flight response”

• “Freeze and Faint response”

stress hormones

Reactions to stress: secretion of several hormones including glucocorticoids, catecholamines, GH and PRL the effect of which
is to increase mobilization of energy sources and adapt the individual
to its new circumstance

vasopressin (AVP)/antidiuretic hormone (ADH)

Acute stress: rapid release of AVP from the hypothalamus.

• rough handling, the approach of a predator, venipuncture

Chronic stress: ↑ secretion of AVP (blood pressure↑)

• isolation, improper housing conditions

gonadotropins

→ Stress: suppression of Gn and gonadal steroid hormones.

→ Prolonged exposure to stress: complete impairment of the reproductive function

thyroid hormones

→ Thyroid function is usually down-regulated during stress: T3 and T4 ↓

→ Stress inhibits TSH secretion through the action of glucocorticoids on the CNS

stress related to welfare

• Effect of kennelling on dogs

• Capture of wild fish/wildlife

• Castration of farm animals

• Sheep shearing

• Branding

welfare and chronic stress

Chronic stress can create pre-pathological states

• Reduced immunity

• Hypertension

• Enlarged adrenal gland

• Lack of growth

• Weight loss

• Reduced fertility

• Gastrointestinal ulcers

distress

→ A state in which an animal, unable to adapt to one or more stressors, is no longer successfully coping with it’s environment and its well-being is compromised

→ Can follow both acute and chronic stress, provided that the body’s biological functions are sufficiently altered, and its coping mechanisms overwhelmed (Moberg, 2000).

→ Stress and distress are dissociable concepts, distinguished by an animal’s ability or inability to cope or adapt to changes in its immediate environment and experience

stress and the immune response

→ LONG-DISTANCE TRANSPORT, SOCIAL INSTABILITY, PARTURITION.

→ Very high levels of cortisol may have inhibitory effects on different parts of the immune response (decreased circulating lymphocytes, decreased phagocytosis, reduced production of cytokines) and thus make animals vulnerable to infection

stress: neurobiological measures

→ Brain activity (EEG, MRI)

→ Learning and memory

→ Neurotransmitters

• Opioids

• Dopamine

• Prolactin

opioids

→ Three types: endorphins, enkephalins, dynorphins; different receptors: kappa (ĸ), mu (μ)

→ Functions

• Stress-induced analgesia

• Control hormone release

• Perception of pleasurable stimuli

→ Lambs: increase in plasma β-endorphin during castration, tail- docking and mulesing (Shutt et al., 1987)

→ Tethered sows: passive sows higher μ-receptor density than group- housed sows; stereotyping sows low k- and μ -receptors (down- regulation?)

dopamine

• Catecholamine.

• Various receptors: (D1, D2, D4)

• Mood, locomotion, voluntary movement.

• DA is involved in the reward center of the brain.

• Stereotypies: sows in stalls, bar-biting: low dopamine

prolactin

→ Pituitary gland

→ Modulates emotions acute stress response

→ Hospitalised dogs (Siracusa et al., 2010)

→ Appeasing pheromone associated with lower plasma PRL, but

not associated with dogs’ behavior or welfare

metabolic stress

• Sepsis (infection)

• Trauma (including burns)

• Surgery

• Once the systemic response is activated, the physiologic and metabolic changes that follow are similar and may lead to septic shock

metabolic responses to stress

• Glucose

• Lactic acid

• Beta-hydroxybutyrate (ketosis)

• Haematocrit (red blood cells)

• Muscle enzymes: creatine kinase

• Hormones: insulin, thyroid hormones

physiological stress indicators

• Laying hens: corticosterone blood and faeces, heterophil/lymphocyte (H/L) ratio,

• Dairy cattle: heat/cold stress, dehydration; environmental (toxic metal pollutants, chemical fertilizers, pesticide contamination); nutritional (acidosis, bloat, hypocalcemia, ketosis, hypomagnesaemia, mycotoxin/plant toxin); management (handling , transportation, seasonal changes)

• Gait: horse, dogs

biosensors technology

→ Biosensors: devices that have the potential to quantify physiological, immunological and behavioral responses of livestock and multiple animal species.

• Novel biosensing methodologies offer highly specialized monitoring devices for the specific measurement of individual and multiple parameters covering an animal’s physiology as well as monitoring of an animal’s environment:

• health monitoring, disease detection and isolation

• detection of reproductive cycles (e.g., P4 in the milk)

• monitor physiological wellbeing via analysis of the animal’s environmentf

monitoring jaw movement of cattle to know the grazing efficiency

→ Jaw movements define the grazing behavior of the cattle; 3 different classes of biosensors can be used to identify such movements: mechanical sensors (pressure sensors), acoustic sensors (microphone) electromyography sensors

in vivo implanted biosensor to analyze stress in fish

Implantable biosensor that detects the composition of eyeball sclera
interstitial fluid in fish. The contents of the fluid correlate well with their
concentrations in blood. Stress due to changes in water chemistry,
dissolved O2 content, pH, and metal toxicity were monitored, and
behavioral changes such as attacking behavior and visual irritation
were recorded

bioacoustic monitoring of poultry using biosensors

• To identify genetic strains & sexes of the birds (Pereira et al., 2015)
• Sound signals collected using microphones and a data collection card
analyzed by a neural network pattern-recognition system
can detect and diagnose necrotic enteritis derived from
the infection of Clostridium perfringens type A (Sadeghi et Al., 2015) Newcastle Disease, Bronchitis Virus, and Avian Influenza

humane farm animal care: the app

Commercial broiler production
• continuous health/welfare assessment to assure good flock performance, profitability, meat quality, granting competitiveness/access to international markets (some countries/premium labeling programs: verification optimal
welfare).
• Incidence of the most relevant health/welfare indicators and frequency of
the birds affected in the flock (immobility, severe lameness, injuries, unwanted behaviors). Recorded data: immediately
available (CSV format for outputs ); a report, warning message

The world's first dog emotion sensor (TailTalk)

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fitbark

essentially a Fitbit for your dog, as it will track your dog’s activity throughout

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