Daniel Weary

Much recent research in the field of animal welfare science includes a focus on understanding individual variation in behaviour, rather than on group averages, and a growing body of literature is now describing stable individual differences in animal behaviour, also called personality traits and coping styles. The aim of my thesis was to explore the potential relationships between social behaviour, personality and coping style in dairy cattle. In Chapter 1, I give a general introduction to the concept of animal welfare and the context of my research. In Chapter 2, I provide a narrative review of social behaviour and individual differences in cattle in which I identify gaps in the literature that I address in the subsequent experimental chapters. Chapter 3 describes a study of indoor, group-housed cattle given the opportunity to access an outdoor bedded pack, such that individual cows could choose when to leave and to return. Some cows formed preferential associations (i.e., moved in and out of the barn together) indicating that a cows’ decision to move can be affected by others in their social group. In Chapter 4, I explored whether dairy calves benefit from the presence of a social partner during recovery from a painful procedure using a conditioned place avoidance paradigm. I found no evidence that the presence of a social partner affected avoidance; the social partner did not appear to provide a buffer for this experience. Calves varied greatly in their avoidance response, but this variation was not explained by differences in fearfulness. In Chapter 5, I characterized the coping strategy used by dairy heifers when introduced into a new social group and found that some heifers engaged in more agonistic interactions (consistent with a more proactive coping style), while others avoided their new pen mates (suggesting a reactive coping style). The strategy used affected their time-budget and behavioural synchronization with the new social group. Collectively, the results of my thesis provide new insights in how dairy cattle vary in their social behaviour when faced with three management practices: when offered outdoor access, when subjected to a routine painful procedure, and when regrouped.

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There is mounting evidence that current laboratory housing practices negatively impact rodent welfare. Environmental enrichment is generally recommended to improve housing, but definitions and applications of enrichment vary widely. The aims of this thesis were to explore the concept of environmental enrichment and to test applied strategies to improve housing for rodents in laboratories. In Chapter 2, I conducted a metareview of environmental enrichment for rats and mice. Authors most often supported the provision of social companions, nesting material, shelters, foraging opportunities, and larger environments (for rats). However, authors often described perceived risks or requirements of enrichment, which represent potential barriers to implementing enrichment. In Chapter 3, I investigated how the addition of an upper loft area affects the behaviour of rat dams housed in laboratory cages with their pups. My results suggest that dams use lofts as an area to get away from pups, allowing for more natural weaning and improved emotional states. In Chapter 4, I conducted a similar experiment with mouse dams housed with their pups in shoebox cages. I found that elevated tunnels were not universally effective at altering dam behaviour or welfare, and outcomes differed according to genetic strains. In Chapter 5, I gave shoebox-housed mice access to playpens on a regular basis and tested whether this was a positive experience for them. Mice showed increased anticipatory behaviour and speed of entry, indicating that playpen access was rewarding; they also engaged in a range of natural behaviours while in the playpens. In Chapter 6, I assessed anxiety, aggression, and stereotypic behaviour to determine how regular playpen access impacted mouse welfare. Playpen access improved some welfare measures, but outcomes tended to vary according to genetic strain. Collectively, this work suggests that there are welfare benefits to housing rodents with resources that allow for more diverse or motivated behaviour, but not all strategies will be equally impactful for welfare. More specific and value-neutral terms should be used to describe elements of an environment and how they are believed to affect the welfare of the animals.

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Meaningful societal dialogue about the use of animals for scientific purposes requires a level of transparency regarding the procedures these animals are likely to experience and the processes institutions engaged in using animals employ to determine what is acceptable. The overall thesis objective was to better understand social licence to use animals for scientific purposes and the role of institutional transparency in this process. Analysis of interviews with research animal facility managers and attending veterinarians at Canadian universities showed the interpretation of institutional transparency varied within and between universities, institutional transparency could be influenced by internal and external pressures, and the main barrier to increased transparency was a lack of motivation to change. Transparency was conceptualized in four ways: 1) true transparency; communication of information for the sake of openness, 2) misguided transparency; attempt to educate people about animal research because then they will support it, 3) manipulative transparency; selective release of positive stories to direct public opinion, and 4) fearful non-transparency; not communicating any information for fear of negative opposition to animal research. Given the diverse understanding of the purpose of transparency, I suggest that active and sustained communication between senior administrators, university veterinarians, animal care staff, and scientists is necessary to build a consensus on how to pursue transparency. While generating consensus at the local institutional level is important, substantial progress would likely benefit from involvement of all stakeholders to work collaboratively and agree to a shared vision for transparency. Analysis of a mix-methods survey that requested public input on proposed animal experiments found that many participants provided substantive and nuanced input that could aid in institutional decision making including social policy alternatives. Analysis of a second mix-methods survey found the public expected oversight for invertebrate animals used for scientific experiments and the absence of this oversight decreased public confidence and trust in scientists. In summary, my results suggest that increased information in the public domain about these practices, incorporation of societal values into decision making, and increased opportunities for participation in research animal governance could help institutions maintain social licence for these practices.

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Whether they live in our homes, farms or laboratories, many animals are subjected to painful procedures. In humans, pain assessment is mostly done through verbal self report, but the assessment of pain in non-verbal humans and animals remains a challenging task.Pain can be divided in two main components: a reflex response, and an emotional experience. The focus of pain research has largely been centered around reflex responses when animals (and human neonates until recently) are the ones subjected to pain. The aim of this thesis was to address this gap by developing a method to assess the emotional experience (or ‘affective state’) that dairy calves go through during painful procedures. To do so, the focus of our novel approach was on how animals formed memories of procedures they were subjected to. In the first chapter, I reviewed the literature on the assessment of emotion in dairy cattle. I highlighted that many measures reflect how aroused animals are rather than whether they are in a positive or negative state (valence), but that measures based on cognition were promising in evaluating valence. In the second chapter, I studied the pain caused by different injection methods by looking at how much milk calves were willing to give up to avoid injections. Although all methods were more aversive than not receiving an injection, intramuscular injections were more aversive than subcutaneous or intranasal. In the third, fourth and fifth chapter, I studied how calves remembered different methods of disbudding (a procedure that prevents horn growth) by looking at how much they would avoid the place where they experienced the procedure. I found that calves remember disbudding as negative and that learned aversion is reduced if calves are provided pain control both during and after the procedure.In summary, calves showed not to be limited to a ‘knee-jerk’ response to pain. Rather, they formed impactful memories that affected their future behaviour, exhibiting complex emotional processing of pain.

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Carbon dioxide (CO₂) is commonly used to kill laboratory rats, but the humanness of this method remains controversial. Cumulative evidence indicates that CO₂ elicits negative emotions in rats. However studies using inescapable exposure (forced exposure) have shown contrasting results. Understanding individual differences could allow for stronger inferences regarding rat experiences when exposed to CO₂. The main aim of this thesis was to determine if CO₂ sensitivity is variable between rats. In Chapter 2, I described rat active and passive behaviours during CO₂ forced exposure and assessed consistency of individual differences in rat response to CO₂. Results from Chapter 2 confirmed that rats do not express passive behaviours when exposed to gradually increasing concentrations of CO₂, showed that the individual rat is an important source of variation in the behavioural responses to CO₂, but this variation was not related to individual differences in coping strategies. In Chapter 3, I investigated consistency and stability of rat individual thresholds of aversion to CO₂ across repeated exposures, and I assessed whether other situational-dependent personality traits could account for the variation in response to CO₂. My results suggest that individual differences in rat thresholds of aversion are not related to other personality traits but to sensitivity to CO₂. In Chapter 4, I assessed the effects of an anxiolytic on the individual thresholds of aversion to CO₂. I found that rats experience anxiety when exposed to lower CO₂ concentrations and variation in rat CO₂ sensitivity is driven by individual differences in the onset of these feelings. Collectively these studies suggest that the emotional experience of rats exposed to CO₂ varies among individuals, likely due to differences in the onset of CO₂-induced anxiety. In these studies using aversion tests, all rats avoided CO₂ before losing consciousness, even less sensitive rats when treated with an anxiolytic. Indicating that CO₂ concentrations required to render rats unconscious elicit negative affective states. Further research is necessary to determine what type of emotions, in addition to feelings of anxiety, are experienced by rats at higher concentrations (e.g. intense air hunger or panic), and whether these experiences also vary between individuals.

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Prolonged standing has been related to an increased risk of claw horn disruption lesions (CHDL), likely by increasing the mechanical load on the hoof. Standing behaviour can be affected by management practices. For example, prolonged standing has been reported for primiparous animals after mixing with older cows, presumably as a result of increased social competition. The hoof is believed to be more vulnerable to mechanical damage around calving, making this a period of a particular interest. The aims of this thesis were to evaluate the relationship between standing behaviour around calving and CHDL later in lactation, and to investigate if the social environment affects how heifers behaviourally react to regrouping. In Chapter 1, I summarise the current knowledge regarding factors that can affect standing behaviour, with particular focus on the social environment. As there is no consensus for how to interpret longitudinal locomotion data, I evaluate how assessment frequency, and lameness definition affect measures of lameness incidence in Chapter 2. A single observation of compromised locomotion as criterion for lameness was poorly related to more strict lameness definitions, and to the presence of claw lesions at trimming. In Chapter 3, I evaluate if the positive association between prolonged standing and sole lesions found in experimental studies is present also on commercial farms. Standing time and standing bout duration during the first 2 wk after calving were positively related to the odds of developing sole lesions later in lactation, as was an increase in standing bout duration from pre- to postpartum. In Chapter 4, I investigate if the social environment influence the standing behaviour of newly calved heifers after regrouping. I found no difference in standing behaviour between heifers regrouped to a low-stocked pen with familiar animals and heifers mixed with multiparous older cow at 100% stocking density, and under the conditions used in this study regrouping did not cause prolonged standing. These studies provide evidence that standing behaviour during the transition period is temporally related with CHDL on commercial farms, and suggest that the effect of regrouping on standing behaviour is influenced by the conditions under which regrouping occurs.

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Over the last decades, increasing scrutiny by the public related to farm animal welfare has placed pressure on farmers and veterinarians to adopt practices that lead to improvements in farm animal care. Despite these growing demands from the public, and a growing body of knowledge on what farm animals need and want, challenges remain regarding how to motivate farmers and veterinarians to adopt management changes to improve animal welfare. Dairy calves, in particular, face many welfare challenges in the early stages of life. Considering that the farmer is directly responsible for calf care on dairy farms and the veterinarian is a trusted advisor, this thesis explores how farmers and veterinarians cooperate to improve calf welfare. Chapter 1 introduces key concepts such as animal welfare, motivating factors for behavioral change, and the context for the Canadian dairy cattle industry. Chapter 2 reviews current literature on dairy farmer and veterinarian perspectives on cattle welfare and suggests that increased cooperation between these stakeholders could lead to improvements in welfare by identifying shared values for improving welfare, promoting their different perspectives as complementary, and improving communication. To examine this proposition, Chapter 3 reports on a focus group study that explores how veterinarian concerns and actions related to calf welfare correspond to their professional and personal obligations to improve it. Chapters 4 and 5 report on an interview study with dairy farmers that participated in a benchmark study on calf immune system status and growth. Chapter 4 describes how access to information and peer comparison in the form of benchmark reports motivated farmers to improve calf management. Chapter 5 describes how including the veterinarian in the benchmarking process influenced the ways that farmers viewed their veterinarian as an advisor for calf management. Chapter 6 concludes the thesis with a summary of strengths and limitations of this dissertation and recommendations such as creating interventions to improve calf welfare that complement the current management systems and leverage existing relationships between farmers and veterinarians. 

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Rats are one of the most commonly used animals in research. Differences in rat housing lead to differences in brain, behaviour, physiology and health. These differences can also affect rat welfare and the validity of data obtained from these animals. Few studies have assessed the consequences of housing rats in standard laboratory cages compared to more complex, naturalistic environments; fewer still have assessed these consequences in females, or after more than a few weeks of differential housing. The aim of my thesis was to assess the sustained welfare consequences of housing female rats in standard versus semi-naturalistic laboratory conditions. The psychological well-being of animals is central to the concept of animal welfare, so Chapter 2 provides a review of the scientific methods of assessing affective states in animals, how these methods have been applied to rats, and what the results can tell us about rats’ experience of various emotional states. Chapter 3 investigated rats’ propensity to engage in behaviours that are not possible in standard laboratory cages: burrowing, climbing and standing upright. Results indicated that burrowing and standing upright may be especially important to rats. Chapter 4 assessed the sustained affective consequences of standard versus semi-naturalistic housing using an anticipatory behaviour test. Results indicated that standard-housed rats were experiencing poorer welfare than the semi-naturalistic-housed rats. These studies were not designed to test differences in health between the two housing conditions, but given the very limited amount of research on the long-term health effects of differential housing in rats, Chapter 5 documented differences in body weight and development of naturally-occurring tumours. Standard-housed rats were much heavier than semi-naturalistic-housed rats, but there were no differences in the rate of tumour development. Collectively, these results indicate that, compared to the semi-naturalistic housing assessed in this thesis, standard laboratory housing for rats compromises rat welfare by 1) preventing the performance of important natural behaviours; 2) leading to negative affective states; and 3) leading to overweight animals predisposed to developing other health issues. Implications for rat welfare and the quality of the science obtained from standard-housed rats are discussed, and recommendations are provided.

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Standard practice within the dairy industry is to separate calves from the dam immediately after birth and raise calves in individual pens during the milk-feeding period with little or no contact with conspecifics. I reviewed empirical work (Chapter 2) on the social development of calves, the effects of social isolation and the practices associated with group housing of dairy calves. From this review I identified literature gaps that were explored in the following chapters. In Chapter 3, I explored how pairing age affects performance and feeding behaviour development in dairy calves. Early pairing (3 d of age) increased solid feed intake and weight gains in comparison to late-pairing (42 d of age) and individual housing. In Chapter 4, I investigated how individual housing of calves affects food neophobia. The results suggested that calves raised in a complex social environment are less reluctant to ingest new feed types. Chapter 5 investigated whether being grouped with experienced dairy cows would affect the development of grazing behaviours in pregnant dairy heifers first introduced to pasture. The results indicated that grouping heifers with pasture-experienced cows improves grazing behaviour in the first hours following introduction to pasture. Chapter 6 assessed whether weaned calves would sort a total mixed ration (TMR) and if sorting was affected by the availability of a separate grain source. I found that calves can sort a total mixed ration and that the provision of a separate source of concentrate reduces sorting. I conclude that calves raised in more complex social environments early in life experience benefits related to feeding behaviour development, performance, ability to cope with novelty, and that experienced companions can be used to mitigate stress associated with novelty.

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The welfare of dairy cattle is of rising concern in North America. This thesis explores how stakeholders relevant to dairy production—including those working within but also those external to the industry—interpret issues around dairy cattle welfare, with the aim to unearth the root of disagreements and identify common values between diverse groups. Chapter 1 begins by exploring the relevant literature and identifies important gaps. Chapters 2 and 3 describe multi-cohort focus groups of farmers, veterinarians, and other industry stakeholders. Chapter 2 investigates their interpretations of the priority welfare issues facing the dairy industry and demonstrates that these stakeholders hold a broad conception of animal welfare with the potential to link to values in broader society. Chapter 3 explores how these stakeholders perceive challenges to welfare and their desired solutions for change; it shows consensus for education, particularly in the form of peer-led extension strategies, to address low welfare knowledge among farmers and veterinarians. Chapter 4 describes a survey of non-farming citizens before and after touring a dairy farm and demonstrates that, as with industry stakeholders, citizens’ animal welfare values are diverse. Chapter 4 also shows that citizens respond differently to learning more about dairy farming, with some becoming more concerned and others less so. Chapter 5 then describes the use of an online engagement tool to explore in greater depth what appears to be one of the most contentious practices in dairy production—that of early separation of the dairy calf from the cow. It illustrates that support of this practice varies markedly among stakeholder groups, but that people are often concerned with the same issues regardless of their stance, providing paths for compromise on practice and policy. Chapter 6 concludes with a summary of findings and recommendations, including: 1) farmers should engage with veterinarians and researchers to help them adopt practices in better alignment with societal values (such as pain mitigation), 2) industry decision makers should commit to transparency but also be prepared to listen and adapt to informed critiques, and 3) researchers should explore engagement strategies to aid in conflict resolution between industry and lay citizens.

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The field of wildlife management has been on a collision course with societal values regarding animal use for some time. Although wildlife populations are still managed largely under the “North American model of wildlife conservation” to accommodate consumptive uses, many people, often with different concerns, want to be heard in decisions about wildlife. These human dimensions present a challenge to wildlife management, a field in which policy has been generally driven by experts. This research used several public engagement methods to understand broader attitudes towards wildlife management and how to incorporate them into policy. Participants with varying levels of wildlife experience in British Columbia, Canada, were asked in online and telephone surveys for their attitudes towards, and acceptance of, specific wildlife activities and management practices. Findings indicate a gap between public and expert opinions on invasive (e.g., relocation) and lethal management practices (e.g., problem bears, predator control, protection of endangered species). Problems also emerged with the public view of wildlife feeding. This led to a review of its motivations, types and consequences, and an evaluative framework was proposed to assess when feeding is acceptable. When asked to rate the harm to wildlife caused in various ways (hunting, vehicle collisions, pollution, etc.), experts and the public largely agreed on the relative importance of harms, indicating considerable potential for finding common ground between conservation-oriented and welfare-oriented citizens. However, some current management practices, especially those involving killing animals, lacked broad public support and may be improved upon with public participation in policy development, especially with women, urban residents, those with low wildlife engagement and animal-protectionist values. This could take the form of public polling or increased representation on decision-making committees. Societal expectations for managing human-wildlife interactions in BC documented by this research include ensuring that actions have an appropriate conservation purpose, are controllable, use humane methods, and appear fair to both people and wildlife. Including a broader public, educating both experts and the public on issues of humaneness, and strengthening wildlife and animal protection laws and enforcement, may serve to better align wildlife policy with societal values.

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The pronounced responses of dairy calves to novel events such as weaning and mixing form an obvious welfare concern and represent an important challenge for the dairy industry. I hypothesized that providing calves a more natural social environment would reduce these responses. This thesis consists of 5 chapters, beginning with a general introduction (Chapter 1) and ending with a general discussion and conclusion (Chapter 5). Chapter 2 compares the effects of individual vs. pair housing on calf responses to weaning from milk as well as on the adjustment to a novel pen and novel social partners at mixing. This chapter shows that being housed with a social companion increases starter intake pre-weaning, has a buffering effect on vocal responses at weaning and improves the performance of calves after mixing when compared to calves housed individually. Chapter 3 describes the effects of housing dairy calves with an older companion on the development of feeding behavior before and after weaning from milk. This chapter shows that a weaned companion is an important social model during weaning, stimulating early intake of hay pre-weaning, starter intake post-weaning and improving growth relative to calves housed in groups of similar age. Chapter 4 describes the effects of the early social environment on the behavioral responses of dairy calves to environmental and social novelty. The results from this chapter show that individually housed calves are more reactive to both environmental and social novelty when compared to pair housed calves. Calves housed with an older companion are also more reactive to separation from group members but less reactive to the presence of an unfamiliar calf when compared to calves housed in groups of similar age. Chapter 5 discusses the results of this thesis and suggests that future research on the development of the affective and cognitive abilities of dairy calves in different social contexts can improve the welfare of commercially reared dairy calves. Providing calves access to conspecifics of similar age or an older companion can minimize calf responses to weaning from milk and reduce responsiveness to environmental and social novelty during mixing.

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Given the recent shift towards democratization of science, public engagement (including exploration of public attitudes) on issues related to animal research is important. This thesis explores public attitudes to changing practices in the use of animals in research. Chapter 1 provides a critical review of the existing research related to this topic. Chapter 2 presents a bibliometric analysis of changing patterns in animal use, and documents the increasing use of genetically modified (GM) animals, especially mice and zebrafish. Chapters 3 and 4 describe two online engagement experiments investigating how acceptance of animal-based research is affected by genetic modification, regulation, invasiveness, and the species used. Chapter 3 shows that support for the use of pigs in research decreased when the research involved an invasive procedure or GM animals. Support for invasive research increased when regulation was in place, but regulation had little effect on acceptance of GM animal use. Chapter 4 shows that participants who were willing to support biomedical research on zebrafish were equally willing to support the same research on mice. Participants expressed low levels of support for research involving ethyl-N-nitrosourea (ENU) mutagenesis. Some participants expressed a preference for the use of GM animal models over ENU mutagenesis based on the belief that the former causes less pain, and improves accuracy and efficiency when creating the animal model. Chapter 5 describes an interview study that examined the views of researchers, research technicians, and members of public toward the creation and use of genetically modified animals in biomedical science. The creation and use of GM animals for biomedical research purposes was generally well supported provided that this was associated with tangible human health benefits. However, it was recognized there are obstacles to Three Rs (replacement, reduction, refinement) implementation, and that there should be more effort placed on engaging the public on animal research. Chapter 6 concludes with key policy recommendations: 1) improve scientific reporting, 2) improve data and animal sharing, 3) improve recording of national animal statistics, 4) improve animal welfare assessment, and 5) supplement the Three Rs.

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Marine mammal research often requires marking and tracking animals to collect long-term ecological data, but these procedures may cause pain. The aim of this thesis was to assess the behavioural and physiological effects of invasive marking and tracking techniques used on marine mammals. This thesis consists of 7 chapters, beginning with a general introduction (Ch. 1) and ending with a general discussion (Ch. 7). Chapter 2 reviews the literature on short- and long-term effects of marking and tagging, concluding that the preponderance of studies focus on injuries and behavioural changes and that no research prior to this thesis has assessed post-operative pain in marine mammals. Chapters 3 to 6 describe experiments designed to fill this gap by focussing on pain responses of endangered Steller sea lions to invasive marking (hot-iron branding) and tracking (implanting a tracking device via intra-abdominal surgery) procedures. Seven behaviours associated with post-operative pain were monitored for 3 d pre- up to 12 d post-surgery with the aim of describing behavioural responses after abdominal surgery (Ch. 3) and comparing the efficacy of two analgesic treatments (Ch. 4). In both studies sea lions spent more time with their back arched and standing, and spent less time lying on the ventral side and in locomotion after surgery, regardless of analgesic treatment. Chapter 5 described the behavioural responses of sea lions after hot-iron branding. In the 3 days after branding sea lions spent more time grooming their branded area, less time with pressure on their branded side, and less time in the pool and in locomotion. Chapter 6 assessed physiological (breathing and heart rate) and behavioural responses of anaesthetised sea lions during hot-iron branding. Sea lions had increased heart and breathing rate during and in the minutes after hot-iron branding. Behavioural responses during branding included trembling and head and shoulder movements. These findings illustrate behavioural and physiological responses that can be applied to assessing pain in sea lions, and suggest that more effective analgesic protocols are required to mitigate pain responses after hot-iron branding and abdominal surgery.

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A consequence of the high rates of morbidity and mortality of calves on North Americandairy farms is the necessity to develop tools for early identification of sickness. As thetrend to group-housing increases, the use of automated feeding systems eases the study offeeding behaviour of individual calves within the group. Little is known about thebehavioural changes associated with the onset of disease in dairy calves, especiallychanges in feeding and resting behaviour. The first study of this dissertation examined theeffect of milk feeding level on the feeding and resting behaviour of group-housed dairycalves fed with an automated feeding system. In two separate experiments, calvesallowed high levels of milk (ad libitum milk replacer and 12 L/d milk) showed reducedfrequency of visits to the milk feeder with visits spread throughout the day and a lowintake of concentrate until weaning. Low-fed calves (4 L/d milk or milk replacer) had ahigh frequency of visits to the milk feeder, however the majority of these visits (~ 90%)were unrewarded (i.e. no milk was served) and resulted in increased milk feederoccupancy times compared to high fed calves. Calves fed low levels of milk also spentless time lying down at 4 to 5 wks of age than high fed calves, probably due to theincreased number of visits to the milk feeder. No differences in the incidence of illnesswere found between treatments. These results provide evidence that milk feeding levelaffects the expression of feeding behaviour, so it must be considered when assessingbehavioural changes related to illness. A second study set out to explore the use of asupplemental heat source by sick calves on preference and lying behaviour. During theirfirst 3 d of life calves fed high (12 L/d) or low (4 L/d) levels of milk did not differ inlying times nor did they show differences in preference for the use of the external sourceof heat. Although no calves were diagnosed with illness during the experiment, calvesshowed a marked preference for heat, spending more than 50% of their time under heatlamps regardless of environmental temperature fluctuations. In the third study, I set out todetermine which behaviours were more susceptible to change in calves afflicted withmild sickness. Calves injected with a mild dose of endotoxin showed a decrease in thetime spent at the hayrack, time spent self-grooming and ruminating. Moreover, whensickness was induced, calves showed an increase in the time spent lying and standinginactive. Lastly, the feeding behaviour of naturally sick calves and healthy counterpartsfed high or low levels of milk from 4 previous studies was investigated. Sick calves fedhigh levels of milk showed a decrease in milk intake, visits to the milk feeder andduration of the visits during the day disease was diagnosed and during the subsequent 3 d.Sick low-fed calves only showed a reduction in the duration of the visits to the milkfeeder. In conclusion, milk feeding level plays an important role in the understanding ofthe behavioural changes occuring at the onset of disease. Providing an external source ofheat may increase the welfare of newborn calves and may also prove to be a useful toolfor identifying sick animals, but further validation studies involving sick calves areneeded. Monitoring reductions in milk intake and visits to the automatic feeder in highmilk fed calves may be a useful measure in identifiying sick calves. In contrast, otherbehavioural indicators of activity level, such as standing or lying down, may be moresensitive when identifying sick calves fed low levels of milk

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