Agriculture and Food Systems - Theses

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    Positive Human-Animal Interactions, Early Life Experiences and Stress Resilience in Pigs
    Lucas, Megan Elinor ( 2022)
    Pigs in intensive production systems routinely encounter several challenging situations including abrupt weaning, painful husbandry procedures, intense contact with stockpeople, and exposure to novel social and physical environments. The ability of pigs to cope with these routine stressors has implications for their welfare and productivity and may be affected by their previous experiences with humans. Furthermore, experiences that occur early in life, including interactions with the dam, the physical environment as well as early experiences with humans, may have a profound effect on the development of stress coping mechanisms that impacts how pigs cope with stress throughout their lives. The aim of this thesis was to examine the effects of positive interactions with humans and early life human and housing experiences on stress resilience in pigs. Stress resilience was measured based on: 1. behavioural and physiological responses to stressors such as routine husbandry and management practices, isolation, novelty, and humans; 2. basal behavioural and physiological measurements that reflect how pigs cope with their general environment; and 3. measurements of biological fitness. Overall, positive interactions with humans, including patting, stroking and scratching pigs, reduced pigs’ fear of humans and their stress responses to routine husbandry and management practices imposed by stockpeople. Sows that received 2 min of daily positive human contact during gestation showed less avoidance of and more interaction with stockpeople imposing pregnancy testing and vaccination in the home pens, and piglets that received 3 or 5 minutes of regular positive human contact showed less escape behaviour and vocalisations during husbandry procedures in the lactation period. Providing opportunities for positive human interaction from 0-4 wk of age was extremely effective in reducing fear of humans, based on positively handled piglets showing increased approach and interaction with an unfamiliar human at 2 and 3 wk of age. Although the effects of handling on fear of humans appeared to weaken over time, there was evidence of early positive human contact resulting in pigs showing less fearful responses to a human at 6, 9 and 14 wk of age, indicating that some reduction in fear of humans lasted well beyond the period when the handling treatment was imposed. In addition to reducing fear of humans, there was evidence that early positive human contact conferred broader effects on stress resilience. Early positive handling reduced pigs’ fear of a novel object at 3 wk of age, escape behaviour after weaning, and cortisol concentrations after weaning and after isolation at 7 wk of age. Furthermore, early positive handling reduced pigs’ injuries and increased serum concentrations of brain-derived neurotrophic factor (BDNF) at 4 wk of age, with limited evidence indicating similar effects on these measurements much later in life at 17 wk of age. The early housing environment had a considerable effect on the human-animal relationship, with pigs reared in farrowing crates showing less fear of humans at 2, 3, 4 and 6 wk of age compared to pigs reared in loose farrowing and lactation pens with more space, physical complexity, and opportunity for interaction with the sow. During the lactation period, piglets in loose pens showed more play behaviour and less repetitive nosing of pen mates and had higher concentrations of serum BDNF compared to piglets in farrowing crates, but surprisingly, they were less able to cope with several stressors before and after weaning. During the lactation period, loose pen piglets showed more avoidance of a novel object, a greater intensity of escape behaviour during capture by a stockperson, and more injuries at 2 wk of age. After weaning, loose pen pigs showed more escape behaviour, less inactivity and had higher cortisol concentrations. At 7 wk of age, loose pen pigs showed more vocalising in a novel area and had higher cortisol concentrations after isolation, and at 21 wk of age, they showed more baulking when being moved out of the home pen by a stockperson. This research showed that positive interactions with humans can ameliorate the stress associated with routine husbandry practices involving stockpeople. When imposed early in life, positive handling had an extended effect on reducing pigs’ fear of humans and appeared to foster stress resilience in a general capacity, based on fewer injuries, higher BDNF concentrations and reduced responses to challenges such as novelty, weaning and isolation in positively handled pigs. In addition to reducing fear of humans through habituation and conditioning, brief and regular close human contact early in life may provide a minor challenge to overcome, that improves the competence of pigs to cope with other types of challenges faced in the future. This research also demonstrated considerable differences in the stress resilience of pigs reared in the two housing treatments studied. While piglets in the loose system showed more play behaviour and had higher BDNF concentrations during the lactation period (both of which are linked to stress resilience) they showed far less flexibility in response to stressors such as routine husbandry practices, weaning, isolation, and exposure to novelty and humans. Piglets in the loose system were reared in a more isolated environment with less contact with people and other pigs and less visual stimulation in general. This may have resulted in loose pen piglets having fewer opportunities to learn to cope with small challenges such as frequent and/or close exposure to stockpeople and other pigs, thus increasing their vulnerability to stress. In addition, heightened maternal responses of loose pen sows towards stockpeople may have increased loose pen piglets’ fear of humans. More research is needed to determine the specific features of the early housing environment that affect both immediate and long-term fear and stress responses of pigs. Overall, this research: 1. showed that the early human and housing environment for pigs can have both immediate and longer-term consequences on stress resilience; and 2. contributed to a growing body of work showing that humans are a key determining factor in the welfare of pigs.
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    Warming a cold shoulder: Animal ethics, sentience, and preferences for human interaction in zoo-housed non-avian reptiles
    Learmonth, Mark James ( 2020)
    Animal welfare science has functionally only existed for a little over 50 years. The last three to four decades in particular have seen a relative boom in the rate of expansion, understanding and attention that this discipline has received. Whilst the foundations of animal welfare science mainly focused on identifying and removing negative welfare states in captive animals, modern scientific inquiry is now starting to understand and approach positive welfare states as a crucial part of any sentient being’s experience of life as well. Positive welfare states may include many elements, such as an animal being fit and healthy, experiencing positive moods and affects, and being able to express natural behaviours (or instead, as this thesis will argue, behaviours that are highly motivated and/or highly rewarding). Encouraging, facilitating and maintaining positive animal welfare states in captive zoo animals are a high priority for modern, ethical zoos. However, there is currently a substantial gap in the published literature exploring positive welfare states associated with human (especially visitor) contact in zoo settings. There is limited research that suggests that human-animal interactions in zoos may potentially be rewarding for some animals that are motivated to participate in, and even ‘solicit’, these interactions, from both familiar husbandry providers (zookeepers) and/or unfamiliar zoo visitors. Ethically, zoos operate under a few key theories pertaining to animal welfare, animal rights, and environmental ethics. A few such theories are: Compassionate Conservation, Conservation Welfare, and Duty of Care. These theories take inspiration from multiple philosophical discourses, and many of them co-exist within the zoological and aquaria communities, institutions and (self-regulated) associations. Many individual institutions may favour particular ethical theories over others, and not all zoos are ethically run, nor is their captivity of certain animals justified or adequate. However, many influential voices within zoological associations are creating a robust model for running ‘modern, ethical zoos’. An amalgamation of many theoretical ethical approaches is required to fully articulate why zoos should, and do, continue to exist. The phylogenetic Class Reptilia (reptiles) is now more correctly termed non-avian reptiles, as recent taxonomic amendments have included all extant and extinct animals back to the clade Diapsida, which includes all dinosaurs, and hence all modern birds - Aves. This now makes reptiles a monophyletic group (i.e. with a single common ancestor). Thus, when discussing modern reptiles, such as tortoises, it is proper to distinguish between avian and non-avian reptiles. Currently, none of the non-avian reptile families have been adequately studied in terms of animal behaviour, cognition and animal welfare sciences. These families include: Sub-order Crocodilia – crocodiles, alligators, gharials, & caimans; Order Lepidosauria, which includes both Squamata – lizards and snakes, and Order Rhynchocephalia – Tuatara; and Order Testudines – turtles, tortoises and terrapins. Declarations of sentience (i.e. feelings) made by governments and scientific associations (such as the World Organisation for Animal Health (OIE)) often include reptiles under the assumption of “all vertebrate animals”, but specific declarations of sentience in reptiles are often missing, or overlooked, in scientific writing and welfare-related policies and discussions. Indeed, the historical assumption that reptiles are merely sedentary automata without complex cognitive and sentient capacities persist. Available cognition and sentience research, however, indicates that there is a very solid basis for assuming and declaring that non-avian reptiles do indeed display all relevant capacities to be classified as conscious, aware, and sentient beings. This means that they most likely are consciously aware of their own welfare, and hence their lives and well-being matter to them. This thesis was designed to weave a coherent story connecting animal ethics, states of consciousness, awareness and sentience in non-avian reptiles (that are often overlooked), and experimental research that addresses whether some zoo-housed reptiles perceive human interaction as rewarding, and whether they are indeed motivated to seek these interactions. Three experiments were conducted: An Aldabran Giant Tortoise (Aldabrachelys gigantea) preference test (n=2); a Leopard Tortoise (Stigmochelys pardalis) preference test (n=5); and a zoo visitor survey of behavioural and ethical beliefs about zoo-housed non-avian reptiles, and the acceptability of human-animal interactions and owning wildlife as pets (n=231). Both tortoise preference tests found individual differences between subjects, and I concluded that some individual tortoises do indeed prefer human interaction (shell scratching and neck rubs) over other stimuli in the experimental circumstances. Whether the rewarding component for the tortoises was the interaction with the human or simply a pleasurable outcome was not determined. While these results could not be generalised to all populations of tortoises or reptiles in general, the results showed significant individual preferences amongst the sample populations, indicating that being aware of, and sensitive to, individual animals’ ‘wants’, rather than making decisions at a species level, is warranted for zoo-housed non-avian reptiles. The results of PCAs of visitor survey responses (n=231) found five common ethical beliefs (components) in the sample of zoo visitors, labelled: 1) Human interaction and entertainment priority component; 2) Complicated zoo ethics and animal welfare component; 3) “Wilding”, natural living and anti-captivity sentiments component; 4) Ethical duty of care component; and 5) Animal agency and respect component. There were some significant differences between agreement with Component 2 and respondents’ education level. Furthermore, Wilcoxon’s Signed Rank tests on 3 paired questions (that were answered before and after randomly allocated positive or negative human-animal interaction statements) significantly influenced the re-rated scores to the questions in either the positive or negative direction corresponding to the information provided, showing a significant influence of education (informative statements) on zoo visitor attitudes. Finally, drawing from relevant information of the known capacities of non-avian reptiles, and from the results of the two preference tests conducted herein that indicated some preferences for human interactions by tortoises studied, I investigated an ethical model of human-animal interactions in zoos that may benefit the well-being and positive welfare of both animal and human participants, and proposed some recommendations for improvement of such interactions. These recommendations may be relevant to zoological institutions and their governing associations, and the results of the ethical and experimental chapters within this thesis may help inform evidence-based improvements for non-avian reptile welfare within these institutions.