Scientific assessment of animal welfare

Abstract

Animal welfare is a state within the animal and a scientific perspective provides methodologies for evidence-based assessment of an animal's welfare. A simplistic definition of animal welfare might be how the animal feels now. Affective experiences including emotions, are subjective states so cannot be measured directly in animals, but there are informative indirect physiological and behavioural indices that can be cautiously used to interpret such experiences. This review enunciates several key science-based frameworks for understanding animal welfare. The biological functioning and affective state frameworks were initially seen as competing, but a recent more unified approach is that biological functioning is taken to include affective experiences and affective experiences are recognised as products of biological functioning, and knowledge of the dynamic interactions between the two is considered to be fundamental to managing and improving animal welfare. The value of these two frameworks in understanding the welfare of group-housed sows is reviewed. The majority of studies of the welfare of group-housed sows have employed the biological functioning framework to infer compromised sow welfare, on the basis that suboptimal biological functioning accompanies negative affective states such as sow hunger, pain, fear, helplessness, frustration and anger. Group housing facilitates social living, but group housing of gestating sows raises different welfare considerations to stall housing, such as high levels of aggression, injuries and stress, at least for several days after mixing, as well as subordinate sows being underfed due to competition at feeding. This paper highlights the challenges and potential opportunities for the continued improvement in sow management through well-focused research and multidisciplinary assessment of animal welfare. In future the management of sentient animals will require the promotion of positive affective experiences in animals and this is likely to be a major focus for animal welfare science activity in the early twenty-first century.

A “How-To” Guide for Designing Judgment Bias Studies to Assess Captive Animal Welfare

“…Physiological measures such as corticosteroids measure arousal, but they do not distinguish arousal associated with positive emotions (e.g., excitement and exploratory behavior associated with foraging and mating activity, or an enriched environment: Mendl, Burman, & Paul, 2010a) from arousal associated with negative emotions (e.g., distress in fight or flight : Hemsworth, Mellor, Cronin, & Tilbrook, 2015;Selye, 1976 Cognitive bias measurements should be adaptable for all species. There is an adaptive benefit for all organisms to distinguish rewarding stimuli from dangerous stimuli (Nettle & Bateson, 2011).…”

Different animal welfare orientations towards some key research areas of current relevance to pastoral dairy farming in New Zealand

“…As pointed out by Hemsworth et al (2015), the biological functioning and affective state orientations were initially seen as competing. However, biological functioning is now taken to include affects.…”

The Utility of Iris-pupillary Area Ratio as a Non-invasive Index of Stress in Primates

“…[1][2][3][4][5] An objective and reliable measure of stress is essential to timely intervene optimal animal welfare measures to minimise stress. [6][7][8][9][10][11][12][13] Stress can broadly be classified into three categories based on the degree of sympathetic system activity: 1) Physiological stress, 2) Borderline stress and 3) Pathological stress. [14][15] While several invasive and non-invasive approaches are described to evaluate the degree of stress, [8][9]12,[16][17] objectively quantifying the level of stress has remained a challenge, especially in exotic animals due to the limitations in approaching them.…”

“…[6][7][8][9][10][11][12][13] Stress can broadly be classified into three categories based on the degree of sympathetic system activity: 1) Physiological stress, 2) Borderline stress and 3) Pathological stress. [14][15] While several invasive and non-invasive approaches are described to evaluate the degree of stress, [8][9]12,[16][17] objectively quantifying the level of stress has remained a challenge, especially in exotic animals due to the limitations in approaching them. Progressive elevation in the activity of the sympathetic nervous system is integral to stress, which can be directly quantified by measuring epinephrine/ nor-epinephrine levels in the circulation or indirectly quantified by measuring various autonomic functions influenced by the sympathetic system.…”