The concept of animal welfare is evolving due to progress in our scientific understanding of animal biology and changing societal expectations. Animal welfare science has been primarily concerned with minimizing suffering, but there is growing interest in also promoting positive experiences, grouped under the term positive animal welfare (PAW). However, there are discrepancies in the use of the term PAW. An interdisciplinary group arrived at a consensus that ‘PAW can be defined as the animal flourishing through the experience of predominantly positive mental states and the development of competence and resilience. PAW goes beyond ensuring good physical health and the prevention and alleviation of suffering. It encompasses animals experiencing positive mental states resulting from rewarding experiences, including having choices and opportunities to actively pursue goals and achieve desired outcomes’. The definition also considers individual and species-specific differences. It provides a framework for researchers to investigate PAW and thereby generate innovative, informative and reproducible science. Studies of PAW can contribute to a richer picture of an animal’s life and may elucidate the biological foundations of happiness. The definition creates opportunities to inspire scientific progress in animal biology and to align animal care practices, legislation and markets with societal expectations.

Non-neuronal cells constitute a significant portion of brain tissue and are seen as having key roles in brain homeostasis and responses to challenges. This review illustrates how non-neuronal biology can bring new perspectives to animal welfare through understanding mechanisms that determine welfare outcomes and highlighting interventions to improve welfare. Most obvious in this respect is the largely unrecognised relevance of neuroinflammation to animal welfare which is increasingly found to have roles in determining how animals respond to challenges. We start by introducing non-neuronal cells and review their involvement in affective states and cognition often seen as core psychological elements of animal welfare. We find that the evidence for a causal involvement of glia in cognition is currently more advanced than the corresponding evidence for affective states. We propose that translational research on affective disorders could usefully apply welfare science derived approaches for assessing affective states. Using evidence from translational research, we illustrate the involvement of non-neuronal cells and neuroinflammatory processes as mechanisms modulating resilience to welfare challenges including disease, pain, and social stress. We review research on impoverished environments and environmental enrichment which suggests that environmental conditions which improve animal welfare also improve resilience to challenges through balancing pro- and anti-inflammatory non-neuronal processes. We speculate that non-neuronal biology has relevance to animal welfare beyond neuro-inflammation including facilitating positive affective states. We acknowledge the relevance of neuronal biology to animal welfare whilst proposing that non-neuronal biology provides additional and relevant insights to improve animals' lives.

Background Rat tickling (heterospecific play between rats and the human hand), can promote positive affect and improve laboratory rat welfare. However, individual variation, particularly in response to the standard tickling protocol involving frequent pinning, may limit its effectiveness. Following hypothesis registration (https://f1000research.com/articles/11-1053/v2), we aimed to refine the protocol by testing responses to different amounts of pinning during playful handling (PH), a flexible form of tactile interaction resembling juvenile rough and tumble rat play. Methods Juvenile male and female Wistar rats received six daily 30-second sessions of PH with 0, 1, or 4 pins per session. A non-PH control involved a motionless hand. The primary response variables were the count and variability of 50 kHz ultrasonic vocalisations (USVs), which are measures of positive affect in rats. Additional exploratory outcomes included behavioural and physiological responses in the elevated plus maze and open field tests. Results All PH treatments increased 50 kHz USVs compared to controls, confirming their positive effect. Males showed no difference in USVs across pinning conditions, while females vocalised more in treatments with minimal or no pinning. Except for the highest pinning treatment (P4), females produced more USVs than males across all conditions, including controls. However, reducing pinning did not reliably decrease USV variability or alter behavioural and physiological outcomes. Conclusions Applying 50 kHz USVs as a measure of positive affect, these results confirm that tickling induces positive affect in juvenile laboratory rats. We report the novel finding of sex differences in response to tickling. Females preferred tickling where the amount of pinning is minimised relative to males that showed no preference across tickling treatments. Levels of USVs suggest that females possibly found the applied treatments, including control conditions, more rewarding than males did

Background:Rat tickling (heterospecific play between rats and the human hand), can promote positive affect and improve laboratory rat welfare. However, individual variation, particularly in response to the standard tickling protocol involving frequent pinning, may limit its effectiveness. Following hypothesis registration ( https://f1000research.com/articles/11-1053/v2), we aimed to refine the protocol by testing responses to different amounts of pinning during playful handling (PH), a flexible form of tactile interaction resembling juvenile rough and tumble rat play. Methods:Juvenile male and female Wistar rats received six daily 30-second sessions of PH with 0, 1, or 4 pins per session. A non-PH control involved a motionless hand. The primary response variables were the count and variability of 50 kHz ultrasonic vocalisations (USVs), which are measures of positive affect in rats. Additional exploratory outcomes included behavioural and physiological responses in the elevated plus maze and open field tests. Results:All PH treatments increased 50 kHz USVs compared to controls, confirming their positive effect. Males showed no difference in USVs across pinning conditions, while females vocalised more in treatments with minimal or no pinning. Except for the highest pinning treatment (P4), females produced more USVs than males across all conditions, including controls. However, reducing pinning did not reliably decrease USV variability or alter behavioural and physiological outcomes. Conclusions:Applying 50 kHz USVs as a measure of positive affect, these results confirm that tickling induces positive affect in juvenile laboratory rats. We report the novel finding of sex differences in response to tickling. Females preferred tickling where the amount of pinning is minimised relative to males that showed no preference across tickling treatments. Levels of USVs suggest that females possibly found the applied treatments, including control conditions, more rewarding than males did.

Across animal welfare science there is a lack of validated models of positive affective states. Previous work has shown that presentation of contrastingly valenced ultrasonic vocalisations (USVs) to rats alters their behaviour. However, the potential of using playback of USVs to induce a positive affective state and promote positive animal welfare has yet to be explored. We used three cohorts of juvenile male Wistar rats (37 days old) in three independent experiments to develop a novel home cage playback paradigm to induce a positive affective state in rats. The intention behind this paradigm was to create a low-stress environment, given the heightened susceptibility of positive affective states to stress. Rats were presented in pairs with a playback track consisting of positively valenced 50-kHz USVs, White Noise (within the 30 – 100kHz range), or Background Noise in their home cage. In Experiments 1 (N = 7 cages) and 2 (N = 14 cages), rats received a single presentation of each playback track in a Latin square experimental design. In Experiment 3 (N = 20 cages), rats received repeated presentations of the same playback track over five consecutive days. Changes in affective state were measured through USV production, approach to the stimulus, and play behaviour. Across all three experiments, the presentation of 50-kHz stimuli USVs increased subject-produced positively valenced 50kHz USVs compared to presentation of Background Noise (e.g. Experiment 2; F2,239 = 6.05, p < 0.05). Similarly, rats also expressed an increase in approach behaviour towards the speaker in response to 50kHz stimuli USVs compared to White Noise and Background Noise (Experiment 3 duration of approach behaviour; F2,479 = 10.55, p < 0.001). Whilst there was complexity in the relationship between the presentation of different acoustic stimuli and play behaviour, rats presented with the 50kHz stimuli showed increased social play in the ten minutes during presentation under some of our test conditions. The impact of acoustic stimuli on measures of affective state across cohorts provides evidence that the home cage playback paradigm holds promise as a method for inducing a positive affective state in rats.

Tickling of rats is a widely used positive handling habituation technique that was modelled on conspecific social (rough and tumble) play. Any neuroendocrine response to tickling has yet to be explored. We aimed to test the hypothesis that as in conspecific play, oxytocin and vasopressin neurons in the paraventricular nucleus (PVN) and supraoptic nucleus (SON) of the hypothalamus are involved in regulating the behavioural response to tickling in female and male juvenile Wistar rats. Rats (n=32/sex) received either tickling (Tickled, n=16/sex) or no hand contact (Controls, n=16/sex). Play behaviours (hand approaches and scampering), 50 kHz and 22 kHz ultrasonic vocalisations (USVs) were quantified. Immediate early gene expression (Fos immunoreactivity; Fos-ir) in oxytocinergic and vasopressinergic neurons of the PVN and SON was quantified. We found that tickled rats called more than controls and that tickled females produced more 50 kHz USVs than tickled male or control rats. In the parvocellular PVN we found that tickled rats, regardless of sex, had lower expression of Fos-ir in oxytocin and vasopressin neurons. In contrast, there was no effect of tickling on the number of Fos-ir magnocellular oxytocin or vasopressin neurons in the PVN or SON. Our findings provide the first evidence that tickling does not replicate the involvement of the central oxytocin and vasopressin systems previously reported following social play in juvenile rats. This is an important consideration for future interpretation of central oxytocin and vasopressin in response to tickling.

Over the last decades, the interdisciplinary field of the affective sciences has seen proliferation rather than integration of theoretical perspectives. This is due to differences in metaphysical and mechanistic assumptions about human affective phenomena (what they are and how they work) which, shaped by academic motivations and values, have determined the affective constructs and operationalizations. An assumption on the purpose of affective phenomenacan be used as a teleological principle to guide the construction of a common set of metaphysical and mechanistic assumptions—a framework for human affective research. In this capstone paper for the special issue “Towards an Integrated Understanding of the Human Affectome”, we gather the tiered purpose of human affective phenomena to synthesize assumptions that account for human affective phenomenacollectively. This teleologically-grounded framework offers a principled agenda and launchpad for both organizing existing perspectives and generating new ones. Ultimately, we hope Human Affectome brings us a step closer to not only an integrated understanding of human affective phenomena, but an integrated field for affective research.

The importance of maternal care in commercial pig production is largely ignored. The sow has little possibility to interact with her piglets, and piglets are often subjected to early weaning or artificial rearing. This study aimed to investigate aspects of physiological and behavioural maternal provisioning that contribute to offspring outcomes. We hypothesised that better maternal care and nutritional provisioning would relate positively to piglet immunity, growth and behaviour. Nineteen sows and their litters were studied in free-farrowing pens. Oxytocin and tumour necrosis factor-α in colostrum/milk and salivary cortisol were sampled from sows throughout lactation. Sows were assessed for dominance rank, response to handling, maternal defensiveness, suckling initiation and termination, posture and sow-piglet contact. Piglets were weighed, measured for body mass index (BMI) and sampled for blood (Immunoglobulin G; at birth). After weaning, they experienced a human approach test (HAT) and novel object test. Correlations were explored between individual sow characteristics, individual piglet outcomes, and between sow characteristics and piglet outcomes averaged by litter. Significant correlations between sow and piglet factors were analysed at the litter level in mixed models with piglet outcomes as response variables and sow characteristics as predictor variables, while accounting for sow parity, litter size and batch. Litters grew faster when their sow had lower cortisol values (P = 0.03), while sows with lower cortisol levels had more successful suckling bouts and engaged in greater amounts of sow-piglet contact. Litters had a lower BMI at weaning when the sow had a higher milk fat percentage at d3. Litters of the most dominant sows took longer to approach the human in the HAT, while litters of sows with higher cortisol at d0 took longer to approach the novel object when assessed on correlations (r = 0.82, P < 0.001) but not when the model accounted for parity and litter size (P = 0.35). Only some of the measured nutritive and non-nutritive sow factors influenced litter performance and behaviour, with parity and litter size also playing a role. Given the continued increase in litter size, but also the interest in loose-housed lactation pens for sows, further research on sows' maternal investment and how it can be optimised is warranted.

The literature examining farmers' views of animal welfare is dominated by the study of cognitive and attitudinal factors. This overlooks how cultural processes can inform what farmers do and why they may be resistant to change when it comes to animal welfare. This paper applies the concept of the "good farmer" to explore how farmers' approaches to welfare are also informed by cultural processes and farmer identity. A more-than -representational lens was applied to an interview study of Scottish livestock farmers (n = 28). This illumi-nated a set of shared practices and principles idealised by farmers as indicative of good welfare and symbolic of a "good farmer": care of the animal's physical body, care of the animal's physical environment, health manage-ment, happy-content animals, stock-keeping skills, objective decision-making, and animal productivity. We explore these in light of the existing "good farmer" literature, discuss how such ideals may impact farmers' welfare-related behaviours, and how supply chain demands may contribute to their restructuring.

Microglia play key roles in brain homeostasis as well as responses to neurodegeneration and neuroinflammatory processes caused by physical disease and psychosocial stress. The pig is a physiologically-relevant model species for studying human neurological disorders, many of which are associated with microglial dysfunction. Furthermore, pigs are an important agricultural species, and there is a need to understand how microglial function affects their welfare. As a basis for improved understanding to enhance biomedical and agricultural research, we sought to characterise pig microglial identity at genome-wide scale and conduct inter-species comparisons. We isolated pig hippocampal tissue and microglia from frontal cortex, hippocampus and cerebellum, as well as alveolar macrophages from the lungs and conducted RNA-sequencing (RNAseq). By comparing the transcriptomic profiles between microglia, macrophages, and hippocampal tissue, we derived a set of 365 highly-enriched genes defining the porcine core microglial signature. We found brain regional heterogeneity based on 215 genes showing significant (adjusted p<0.01) regional variations and that cerebellar microglia were most distinct. We compared normalized gene expression for microglia from human, mice and pigs using microglia signature gene lists derived from each species and demonstrated that a core microglial marker gene signature is conserved across species, but that species-specific expression subsets also exist. Importantly, pig and human microglia shared greater similarity than pig and murine microglia. Our data provide a valuable resource defining the pig microglial transcriptome signature that highlights pigs as a useful large animal species bridging between rodents and humans in which to study the role of microglia during homeostasis and disease. Main Points - Defined a pig microglial transcriptome signature comprising 365 genes. - Demonstrated regional variance in the pig microglial transcriptome across the brain. - Revealed greater similarity between pig and human microglia than mouse.

Rat tickling is a heterospecific interaction for experimenters to mimic the interactions of rat play, where they produce 50 kHz ultrasonic vocalisations (USV), symptoms of positive affect; tickling can improve laboratory rat welfare. The standard rat tickling protocol involves gently pinning the rat in a supine position. However, individual response to this protocol varies. This suggests there is a risk that some rats may perceive tickling as only a neutral experience, while others as a positive one, depending on how tickling is performed. Based on our research experiences of the standard tickling protocol we have developed a playful handling (PH) protocol, with reduced emphasis on pinning, intended to mimic more closely the dynamic nature of play. We will test whether our PH protocol gives rise to more uniform increases in positive affect across individuals relative to protocols involving pinning. We will compare the response of juvenile male and female Wistar rats as: Control (hand remains still against the side of the test arena), P0 (PH with no pinning), P1 (PH with one pin), P4 (PH with four pins). P1 and P4 consist of a background of PH, with treatments involving administration of an increasing dosage of pinning per PH session. We hypothesise that rats exposed to handling protocols that maximise playful interactions (where pinning number per session decreases) will show an overall increase in total 50 kHz USV as an indicator of positive affect, with less variability. We will explore whether behavioural and physiological changes associated with alterations in PH experience are less variable. We propose that maximising the numbers of rats experiencing tickling as a positive experience will reduce the variation in response variables affected by tickling and increase the repeatability of research where tickling is applied either as a social enrichment or as a treatment.

'Tickling' induces positive affective states in laboratory rats as evidenced by the production of 50-kHz ultrasonic vocalisations (USVs), although this has mostly been investigated in males. Juvenile rats emit distinctive 50-kHz USV subtypes. Frequency-modulated (FM) 50-kHz USVs are thought to be associated with positive affect and flat 50-kHz USVs with social communication. FM and flat USVs are produced by both sexes during tickling, but it is unclear whether these calls are produced in relation to particular play-related behaviours, and whether USV subtypes are used in a sexually dimorphic manner during tickling. We tested the hypotheses that FM USVs are associated with tickle-induced play behaviours in a sex-specific way, and that flat USVs are associated with non-play activities. Rats were allocated to one of two treatment groups: tickling (tickled, n = 16/sex) or no hand contact (control, n = 16/sex). Play behaviours (hopping, darting and hand approaches) and FM and flat USVs emitted during the testing session were quantified for each rat, with the frequency of FM and flat USVs made in anticipation of, and during, each behaviour analysed. In females, play behaviours were associated with more flat USVs than in males (before and during; p < 0.001), irrespective of treatment. FM USVs were paired with hopping and darting (before and during; p < 0.001), and in anticipation of hand approaches (p < 0.001) in both tickled females and males compared to controls (both sexes) suggesting that FM USVs are linked with play behaviour. The higher call rate of flat USVs paired with play behaviour in females suggests that there may be sex differences in the role of flat USVs during play. This result is evidence of sex differences in tickle-induced behaviours and has implications for our understanding of the function of different USVs in juvenile female and male rats.

This review paper provides an integrative account regarding neurophysiological correlates of positive emotions and affect that cumulatively contribute to the scaffolding for happiness and wellbeing in humans and other animals. This paper reviews the associations among neurotransmitters, hormones, brain networks, and cognitive functions in the context of positive emotions and affect. Consideration of lifespan developmental perspectives are incorporated, and we also examine the impact of healthy social relationships and environmental contexts on the modulation of positive emotions and affect. The neurophysiological processes that implement positive emotions are dynamic and modifiable, and meditative practices as well as flow states that change patterns of brain function and ultimately support wellbeing are also discussed. This review is part of "The Human Affectome Project" (http://neuroqualia.org/background.php), and in order to advance a primary aim of the Human Affectome Project, we also reviewed relevant linguistic dimensions and terminology that characterizes positive emotions and wellbeing. These linguistic dimensions are discussed within the context of the neuroscience literature with the overarching goal of generating novel recommendations for advancing neuroscience research on positive emotions and wellbeing.

OPINION article Front. Vet. Sci., 24 June 2021Sec. Animal Behavior and Welfare Volume 8 - 2021 | https://doi.org/10.3389/fvets.2021.677872

The importance given to minimising health issues and promoting natural behaviours is a polarising issue within farm animal welfare. It is predominantly thought that members of the public prioritise animals being able to behave naturally over other aspects of farm animal welfare, such as addressing health issues. However, public perspectives may be more multi-dimensional than is generally thought, with the importance given to these different elements of welfare dependent on the situation and state of the animals in question. To examine this, a factorial survey using vignettes, which experimentally manipulated the different levels of health (high health vs. low health) and natural behaviour provision (high behaviour vs. low behaviour), was completed by a sample (n = 810) representative of the UK population (on age, gender, ethnicity). Contrary to the predominant view, this study found animal health had the greatest effect on participants' judgements, explaining more of the variance in their assessments of animal welfare than any other factor. However, findings also indicated that participants considered animal welfare to be most positive when both health issues are minimised and natural behaviours are promoted. Attitudes to natural behaviours also varied more between participants, with females, individuals who do not (regularly) eat meat and those with a greater belief in animal mind giving greater priority to natural behaviours. In the context of public and private welfare standards seeking to meet public expectations, this study provides important insights into how public perspectives of animal welfare are more nuanced than previously thought, influenced by the context of the animal, the aspect of welfare in question and personal characteristics.

Adolescents’ interactions with animals are of increasing interest and their beneficial developmental outcomes are well known. However, negative interactions such as perpetrating cruelty toward animals during childhood and adolescence have been related with child abuse, domestic violence, and later interpersonal violence. Cruelty toward animals by adolescents has been reported predominately in criminal and clinical samples, and links have been made between animal cruelty and interpersonal violence. However, studies often lack a clear definition of animal cruelty and the animal involved. The present study addresses methodological shortcomings by providing a clear definition of the cruelty acts and the animals involved and the time frame within which cruelty acts have been taken place. Therefore, we investigated the prevalence of animal cruelty of 979 British adolescents (419 male, 497 female, Mage = 15.1 ± 1.57 years) by means of a survey questionnaire administered in school. Animal cruelty was investigated encompassing deliberate and nondeliberate cruelty acts, a clear definition of the target animals was included and a time frame was provided. Furthermore, acceptability of animal cruelty, engaging in antisocial behavior, and family affluence were investigated. Results show high reliabilities for the measures applied. Exploratory factor analysis reveals different types of animal cruelty. Gender differences were observed for deliberate and accidental cruelty acts, with boys reporting higher levels than girls. Younger adolescents reported higher accidental cruelty acts than older ones. Acceptance of animal cruelty played a significant role in predicting animal cruelty, together with antisocial behaviors and place of living. The present study shows for the first time the importance of distinguishing between different types of animal cruelty and defining the animals involved.

Societal and scientific perspectives of animal welfare have an interconnected history. However, they have also, somewhat, evolved separately with scientific perspectives often focusing on specific aspects or indicators of animal welfare and societal perspectives typically taking a broader and more ethically oriented view of welfare. In this conceptual paper, we examine the similarities and differences between scientific and societal perspectives of positive welfare and examine what they may mean for future discussions of animal welfare considered as a whole. Reviewing published studies in the field we find that (UK and Republic of Ireland) farmers and (UK) members of the public (i.e., society) typically consider both negatives (i.e., minimising harms) and positives (i.e., promoting positive experiences) within the envelope of positive welfare and prioritise welfare needs according to the specific context or situation an animal is in. However, little consideration of a whole life perspective (e.g., the balance of positive and negative experiences across an animal's lifetime) is evident in these societal perspectives. We highlight how addressing these disparities, by simultaneously considering scientific and societal perspectives of positive welfare, provides an opportunity to more fully incorporate positive welfare within a comprehensive understanding of animal welfare. We suggest that a consideration of both scientific and societal perspectives points to an approach to welfare which accounts for both positive and negative experiences, prioritises them (e.g., by seeing positive experiences as dependent on basic animal needs being fulfilled), and considers the balance of positives and negatives over the lifetime of the animals. We expand on this view and conclude with its potential implications for future development of how to understand and assess animal welfare.