Browsing by Author "Arnott, Gareth"

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    Chicken or fish? Do environmental complexity and stocking density impact affective states of broiler chickens and rainbow trout?
    Anderson, Mallory G. (Virginia Tech, 2021-09-30)
    In commercial settings, broiler chickens and rainbow trout are housed in barren environments under high stocking densities, due to an emphasis on production efficiency. These monotonous housing conditions do not provide broilers or trout with the ability to perform functional, highly-motivated behaviors and increase their susceptibility to excessive anxiety and fear, resulting in negative affective states and poor animal welfare. Affective state (or emotional state) is a cumulative product of short-term life experiences, ranging from positive to negative. Because affective states are largely influenced by environmental condition, determining animal affective state can provide useful information on how to improve housing conditions in order to ensure positive experiences and good animal welfare. Cognitive processes are closely associated with affective state; a "cognitive bias" occurs when affective state influences aspects of cognition, such as judgement and attention. Animals in positive affective states make optimistically-biased decisions during ambiguous situations, judging the situation as if it will produce a positive outcome, and show less bias towards a perceived threat, responding in a less anxious and calm manner. Animals in negative affective states make pessimistically-biased decisions during ambiguous situations, judging the situation as if it will result in a negative outcome. Additionally, animals in negative affective states will bias their attention towards a perceived threat rather than alternative stimuli, responding in an anxious manner. Therefore, judgement and attention bias tests can be used to determine animal affective states. In Chapter 3, a judgement bias test was used to determine affective state of broiler chickens housed in either complex (perches, dust bath, pecking stones, and rotating enrichment objects) or barren (no enrichment) environments under either high or low stocking densities. Broilers housed in complex environments responded more optimistically during the judgement bias test than broilers from barren environments, indicating the former were in a positive affective state. Stocking density did not impact their responses in the judgement bias test, indicating that affective states were not impacted by that treatment. In Chapter 4, an attention bias test was used to determine level of anxiety and a tonic immobility test was used to determine fear in order to investigate affective state of broilers housed in the same conditions as described for Chapter 3. Broilers housed in complex environments were less anxious during the attention bias test than broilers from barren environments, indicating environmental complexity reduced anxiety in broilers. Stocking density did not impact anxiety. Broilers from high stocking density environments had shorter tonic immobility durations than broilers from low stocking density environments, suggesting the former were less fearful. Environmental complexity did not impact fearfulness. In Chapter 5, a judgement bias test was used to determine affective state of rainbow trout housed in either complex (shelter structure and artificial plants) or barren (no enrichment) tanks under either low or high stocking densities. Trout housed in high stocking density tanks responded optimistically during the judgement bias test, indicating they were in a more positive affective state compared to trout housed in low stocking density tanks. Environmental complexity did not impact their responses in the judgement bias test, indicating no effect of enrichments on affective states was found. These results indicate a beneficial relationship of a complex environment on broiler chicken affective state, observed through an optimistic judgement bias and reduced attention bias (anxiety) towards a perceived threat. Thus, providing a complex housing environment for broilers can improve their welfare and result in a positive affective state. Rainbow trout reared at the tested high density resulted in a positive affective state, although complexity did not benefit their welfare. Our results contribute much needed information on stocking densities to ensure fish welfare. Overall, environmental complexity, not stocking density, had a positive impact on broiler chicken affective states. Rainbow trout affective states were positively impacted by stocking density, but not environmental complexity.
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    Effect of Environmental Complexity and Stocking Density on Fear and Anxiety in Broiler Chickens
    Anderson, Mallory G.; Campbell, Andrew M.; Crump, Andrew; Arnott, Gareth; Newberry, Ruth C.; Jacobs, Leonie (MDPI, 2021-08-12)
    Barren housing and high stocking densities may contribute to negative affective states in broiler chickens, reducing their welfare. We investigated the effects of environmental complexity and stocking density on broilers’ attention bias (measure of anxiety) and tonic immobility (measure of fear). In Experiment 1, individual birds were tested for attention bias (n = 60) and in Experiment 2, groups of three birds were tested (n = 144). Tonic immobility testing was performed on days 12 and 26 (n = 36) in Experiment 1, and on day 19 (n = 72) in Experiment 2. In Experiment 1, no differences were observed in the attention bias test. In Experiment 2, birds from high-complexity pens began feeding faster and more birds resumed feeding than from low-complexity pens following playback of an alarm call, suggesting that birds housed in the complex environment were less anxious. Furthermore, birds housed in high-density or high-complexity pens had shorter tonic immobility durations on day 12 compared to day 26 in Experiment 1. In Experiment 2, birds from high-density pens had shorter tonic immobility durations than birds housed in low-density pens, which is contrary to expectations. Our results suggest that birds at 3 weeks of age were less fearful under high stocking density conditions than low density conditions. In addition, results indicated that the complex environment improved welfare of broilers through reduced anxiety.
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    Environmental complexity positively impacts affective states of broiler chickens
    Anderson, Mallory G.; Campbell, Andrew M.; Crump, Andrew; Arnott, Gareth; Jacobs, Leonie (Nature Portfolio, 2021-08-20)
    Affective state can bias an animal’s judgement. Animals in positive affective states can interpret ambiguous cues more positively (“optimistically”) than animals in negative affective states. Thus, judgement bias tests can determine an animal’s affective state through their responses to ambiguous cues. We tested the effects of environmental complexity and stocking density on affective states of broiler chickens through a multimodal judgement bias test. Broilers were trained to approach reinforced locations signaled by one color and not to approach unreinforced locations signaled by a different color. Trained birds were tested for latencies to approach three ambiguous cues of intermediate color and location. Broilers discriminated between cues, with shorter latencies to approach ambiguous cues closest to the reinforced cue than cues closest to the unreinforced cue, validating the use of the test in this context. Broilers housed in high-complexity pens approached ambiguous cues faster than birds in low-complexity pens–an optimistic judgement bias, suggesting the former were in a more positive affective state. Broilers from high-density pens tended to approach all cues faster than birds from low-density pens, possibly because resource competition in their home pen increased food motivation. Overall, our study suggests that environmental complexity improves broilers’ affective states, implying animal welfare benefits of environmental enrichment.
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    Investigating the Domestication Syndrome Hypothesis: To What Extent Does Morphology Predict the Behavior and Physiological Stress Response of Dogs and Cattle?
    Platzer, JoAnna Marie (Virginia Tech, 2023-09-06)
    The Domestication Syndrome Hypothesis posits that domesticated animal species exhibit a shared set of traits encompassing behavioral, physiological, and morphological characteristics. While this hypothesis has garnered significant attention, the evidence supporting its universality remains limited, particularly in species such as dogs and cattle. In this dissertation, I examined the Domestication Syndrome Hypothesis in mixed breed pet and shelter dogs as well as Holstein dairy heifers. This investigation focused on behavioral responses, physiological reactivity, and Domestication Syndrome Hypothesis-associated morphological variables in relation to human interaction. First, I explored the behavioral responses of Holstein dairy heifers representing a range of white spotting phenotypes towards people and handling, and their physiological response towards handling during an industry-standard palpation procedure. Additionally, I explored three pigmentation variables (coat color/pattern, eumelanin pigmentation, and white spotting) in dogs residing in a known stressful environment, an animal shelter. I assessed their baseline in-shelter cortisol and their cortisol response to an intervention in which they left the shelter to spend time with people. Lastly, I investigated citizen science behavioral surveys of owned mixed breed dogs to determine potential correlations between white spotting or ear set and various behavioral factors, including human sociability and aggression. Altogether, I found partial support for the Domestication Syndrome Hypothesis: some results aligned with the expectations of the Domestication Syndrome Hypothesis and some did not. Notably, in Holstein dairy heifers, I observed that less white spotting predicted a greater increase in cortisol levels and a higher rate of stepping in response to palpation, results that support the premises of the Domestication Syndrome Hypothesis. Moreover, in owned mixed breed pet dogs, I found that human sociability positively correlated with white spotting and floppier ears and that decreased arousal, decreased aggression, and increased proximity-seeking correlated with floppier ears, further supporting the Hypothesis. However, many of the correlations predicted by the Hypothesis were not statistically significant or exhibited an opposite direction to what was expected. For instance, more extensive white spotting in Holsteins predicted a higher rate of vocalization during palpation, pigmentation did not significantly predict cortisol levels in shelter dogs, and in owned mixed breed dogs playfulness and biddability negatively correlated with white spotting while biddability negatively correlated with floppier ears. Prior research on the Domestication Syndrome Hypothesis in dogs did not find covariation between domestication-associated behavioral and morphological traits, which the researchers suggest may have been driven by modern breeding practices; this confound could have also impacted my studies. Together, the results – both supportive and contradictory – included in this dissertation contribute to our understanding of the Domestication Syndrome Hypothesis. Further research is needed to reconcile these inconsistencies and explore the underlying mechanisms behind the observed relationships. By expanding sample sizes, using more standardized study designs, and investigating causative mechanisms, future studies can enhance our knowledge of the Domestication Syndrome Hypothesis and its implications in the domestication process of animals.
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    Surgical castration in piglets: its impacts on pain and affective states
    Neary, Jessica Michelle (Virginia Tech, 2023-01-17)
    Surgical castration of young male piglets is an extremely common husbandry procedure in the United States swine industry, with nearly 100% of males castrated. The procedure is performed primarily to prevent the occurrence of boar taint in the meat and to reduce aggression as the animals age. No research has investigated the impact of surgical castration on the long-term mood states – also known as the affective state – of piglets, but it has been proven to cause both acute and chronic pain that can last up to 4 days, modify piglet behavior, and reduce weight gain. Because of this, feasible approaches for pain alleviation are needed. A hinderance to this is that currently no analgesics are approved for piglets. In addition, we need validated, practical methods to recognize pain in piglets in order to help researchers, veterinarians, and caretakers to identify the need for analgesics. One useful tool for this could be the Piglet Grimace Scale, which has previously been validated in this context, but is not widely applied. The current lack of analgesic use during castration may be cause for concern for consumers, however little is known about the public's knowledge on the industry's practices. Therefore, the thesis' objectives are to (1) assess the impact of surgical castration on pain and affective states, (2) determine people's ability to recognize pain expression after surgical castration, and (3) get insights into public perception of swine industry practices. In Chapter 3, we assessed the impact of surgical castration and practical pain alleviation methods during and after castration on piglets' short and long-term affective states and activity levels. Piglets were surgically castrated, castrated with analgesics, or sham-handled at 3 days of age. Data on piglets' activity (using accelerometers), tails (affective states), and grimaces (pain expression) were collected for 1, 6, and 24 hours after castration treatments while piglets were in their home pens. An attention bias test was then performed in week 1 and 12 to assess anxiety (an affective state). Home pen activity after castration treatments suggested that there was a positive impact of using analgesics. The piglets' behavior (eating) and activity during the attention bias test at week 1 suggest a negative impact of castration on affective states. The differences observed in week 1 were no longer found in week 12, suggesting that any impact of surgical castration at 3 days of age on affective states are no longer detectable at 12 weeks of age. In Chapter 4, through an online survey we investigated the validity and reliability of Piglet Grimace Scale ratings applied by swine industry professionals and the general public, to assess its potential utility in non-research settings. The survey contained a training, followed by 9 piglet images showing facial expressions immediately after castration or sham-handling. Both response groups were able to recognize pain in castrated piglets. However, both response groups overestimated pain experience compared to trained experts, suggesting more training may be necessary. Nevertheless, overall, the scale can be widely applied by veterinarians, industry professionals and even members of the public. In Chapter 5, a survey provided initial insights into public knowledge and perceptions on castration and analgesia use and compared this to industry stakeholders. The results show that knowledge on industry practices was especially lacking for public respondents, but also for a minority of industry respondents, indicating opportunities for education and further research on the topic.