Piglets' behaviour and performance in relation to sow characteristics

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.

Defining the pig microglial transcriptome reveals its core signature, regional heterogeneity, and similarity with human and rodent microglia

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 characterize 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 239 highly enriched genes defining the porcine core microglial signature. We found brain regional heterogeneity based on 150 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. Our data provide a valuable resource defining the pig microglial transcriptome signature that validates and 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.

Stage 1 Registered Report: Refinement of tickling protocols to improve positive animal welfare in laboratory rats

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.

Stem cell-derived porcine macrophages as a new platform for studying host-pathogen interactions

BACKGROUND

Infectious diseases of farmed and wild animals pose a recurrent threat to food security and human health. The macrophage, a key component of the innate immune system, is the first line of defence against many infectious agents and plays a major role in shaping the adaptive immune response. However, this phagocyte is a target and host for many pathogens. Understanding the molecular basis of interactions between macrophages and pathogens is therefore crucial for the development of effective strategies to combat important infectious diseases.

RESULTS

We explored how porcine pluripotent stem cells (PSCs) can provide a limitless in vitro supply of genetically and experimentally tractable macrophages. Porcine PSC-derived macrophages (PSCdMs) exhibited molecular and functional characteristics of ex vivo primary macrophages and were productively infected by pig pathogens, including porcine reproductive and respiratory syndrome virus (PRRSV) and African swine fever virus (ASFV), two of the most economically important and devastating viruses in pig farming. Moreover, porcine PSCdMs were readily amenable to genetic modification by CRISPR/Cas9 gene editing applied either in parental stem cells or directly in the macrophages by lentiviral vector transduction.

CONCLUSIONS

We show that porcine PSCdMs exhibit key macrophage characteristics, including infection by a range of commercially relevant pig pathogens. In addition, genetic engineering of PSCs and PSCdMs affords new opportunities for functional analysis of macrophage biology in an important livestock species. PSCs and differentiated derivatives should therefore represent a useful and ethical experimental platform to investigate the genetic and molecular basis of host-pathogen interactions in pigs, and also have wider applications in livestock.

Positive Welfare in Science and Society: Differences, Similarities and Synergies

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.

Factors Influencing the Prevalence of Animal Cruelty During Adolescence

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, M_age = 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.

The Importance of Farm Animal Health and Natural Behaviors to Livestock Farmers: Findings From a Factorial Survey Using Vignettes

There is increasing interest in enabling positive experiences, not just minimizing negative experiences, to improve the welfare of farmed animals. This has influenced the growth of private agri-food standards and supported arguments to integrate animal welfare into policy on sustainability and climate change. However, much research finds that farmers predominantly focus on the minimization of negatives (i.e., health issues). This may impact the positioning of farmers within these wider societal debates, affecting their social license to farm. It is thus important to better understand farmers' priorities relating to the minimization of negative factors (e.g., health issues) and the promotion of positive experiences (i.e., natural behaviors). A novel 2 × 2 factorial survey using vignettes, which experimentally manipulated health (health issues minimized/not minimized) and natural behavior (natural behaviors promoted/not promoted) provision, was completed by livestock farmers (n = 169), mostly with extensive systems, in the UK and Republic of Ireland. The majority (88%) considered “minimizing health issues” to be the most important factor for animal well-being. However, the overall welfare of animals was judged to be highest when both health and natural behaviors were supported. Several individual characteristics, including farming sector, production system, gender, belief in animal mind and business type influenced how participants judged the welfare of animals and the level of importance they gave to health and natural behaviors. Findings suggest that although farmers prioritize the minimization of health issues they want animals to be both healthy and able to express natural behaviors, and individual characteristics are important for understanding farmers' welfare-related judgements.

Negative play contagion in calves

Play is a strong outwardly directed, emotional behaviour and can contagiously spread between individuals. It has been suggested that high-playing animals could 'seed' play in others, spreading positive affective states. Despite the current interest in play contagion there has been no previous attempt to measure the strength of the play contagion effect. The calf (Bos taurus) is ideal for testing the strength of play contagion as play in calves is strongly related to energy intake from milk. We manipulated play in calves through their milk allowances and housed the calves in uniform groups all on the same milk allowance (high = UHigh or low = ULow) or in mixed groups with calves in the same group receiving either a high (= MHigh) or low (= MLow) milk allowance. We measured locomotor play using accelerometers on two consecutive days when calves were four and eight weeks old, in order to study play contagion over a protracted developmental window. We anticipated that differences in the level of play contagion between treatment groups would result in difference in the play levels observed in the MLow and ULow individuals. Contrary to our expectations we found that spontaneous play was suppressed in the high-milk calves housed in mixed groups (MHigh), in comparison to calves housed with group mates all receiving high-milk (UHigh). These results are the first to quantify a negative play contagion effect, particularly in a situation of long-term contact, and may suggest that negative contagion has a stronger effect on play behaviour than positive contagion.

Discriminating spontaneous locomotor play of dairy calves using accelerometers

Play behavior is a promising welfare indicator in dairy calves because it decreases in negative situations such as pain or hunger and increases in positive contexts such as in appropriate social environments. Directly measuring play is time consuming because it is performed in irregular bouts and can be inconsistent over days. To facilitate automatic recording of play, previous studies fitted triaxial accelerometers to the hind legs of calves and measured the velocity of movements in large arenas; high correlations were reported between vertical axis peak duration and the duration of locomotor play. The current study aimed to validate accelerometers for recording spontaneous locomotor play in calves' home pens over longer periods. Data were collected from 48 Holstein Friesian calves, housed in groups of 3 in pens of 10 m2, at either 4 or 8 wk of age. Acceleration at the vertical axis of the hind leg was recorded at a rate of 1 Hz. One active time period for each calf was randomly selected (mean duration ± standard deviation = 34 ± 9 min). From video of the corresponding time period, the frequency of locomotor play events, consisting of run, turn, and buck/buck-kick, was recorded using behavior sampling. Combined counts of play events were highly correlated (Pearson r = 0.91) with counts of acceleration peaks. However, for calves with higher levels of locomotor play, this method underestimated the extent of play. Alternatively, run, turn, and buck events obtained from video were transformed by creating intervals of 10 s and then classifying each 10-s interval as comprising events of play ("play") or not comprising events of play ("no play"). The corresponding accelerometer data for all 10-s periods, equaling 10 consecutive readings each, were classified into play or no play by using quadratic discriminant analysis; 79% of periods with locomotor play were correctly classified. Counts of observed play intervals correlated with the counts of play periods from accelerometers (r = 0.87), but the discriminant analysis consistently overestimated play. In conclusion, accelerometer measurements at 1 Hz (in 1-s intervals) and at the vertical axis cannot be used alone to exactly quantify absolute levels of locomotor play in the home pen. However, counts of peak accelerations can provide a rough estimate of inter-individual differences in play events, and discriminant analysis can be used as a proxy for one-zero sampling of inter-individual differences in locomotor play.

Prioritization of Farm Animal Welfare Issues Using Expert Consensus

Prioritization of animal welfare issues can help identify which areas most require research funding and raise awareness of best practices. A modified Delphi method was used to obtain expert opinion on the highest priority welfare issues for UK farmed livestock. Fifty-eight UK-based experts were recruited onto the study, with a minimum of 3 years experience of working with either cattle, pigs, poultry, or small ruminants (12-16 experts per group). Experts were chosen to represent a broad range of opinions. Two rounds of surveys were conducted online using Online Survey, and the final round was an in-person workshop with 21 experts. In the first survey, experts were provided with a comprehensive list of species-specific welfare issues derived from the literature. Participants were asked to score each welfare issue, for (i) severity, (ii) duration, and (iii) prevalence on a 6-point Likert scale. The results of the first survey were reviewed and the welfare issues which scored a neutral-to-high response (scores 3-6) were carried forward. In round 2, participants were asked whether they agreed or disagreed with the rankings that were made from the results of round 1. The final stage of the process was a workshop, which consisted of a combination of group exercises and discussions, to reach the final consensus. Welfare priority lists were divided into two categories: severity/duration, and prevalence, to identify the priority welfare issues affecting individual animals and the population, respectively. Across all farmed species common concerns were inadequate or inappropriate nutrition, inability of stockpeople to recognize or treat welfare issues (such as pain or behavioral problems), lameness, chronic or endemic health issues, euthanasia and mortality and morbidity of neonates. Specific concerns related to behavioral restriction and damaging or abnormal behavior in pigs, poultry and dairy animals, inadequate housing for pigs and poultry, consequences of breeding decisions in pigs and poultry, and lack of access to veterinary care in sheep and beef. This Delphi process resulted in consensus on the most significant welfare challenges faced by UK livestock species and can help to guide future research and education priority decisions.

What Is so Positive about Positive Animal Welfare?-A Critical Review of the Literature

Simple Summary

Positive animal welfare (PAW) is thought to have come about as a response to there being too much of a focus on avoiding negatives in animal welfare science. However, despite its development over the last 10 years, it is not clear what it adds to the study of animal welfare. To clarify this, we conduct a review of the literature on PAW. We aim to identify the characteristic features of PAW and to show how PAW connects to the wider literature on animal welfare. We find that the PAW literature is characterised by four features: (1) positive emotions which highlights the capacity of animals to experience positive emotions; (2) positive affective engagement which seeks to create a link between positive emotions and behaviours animals are motivated to engage in; (3) quality of life which acts to give PAW a role in defining an appropriate balance of positives over negatives and; (4) happiness which brings a full life perspective to PAW. While the first two are already well situated in animal welfare studies the two last points open research agendas about aggregation of different aspects of PAW and how earlier experiences affect animals’ ability to have well-rounded lives.

Abstract

It is claimed that positive animal welfare (PAW) developed over the last decade in reaction to animal welfare focusing too much on avoiding negatives. However, it remains unclear what PAW adds to the animal welfare literature and to what extent its ideas are new. Through a critical review of the PAW literature, we aim to separate different aspects of PAW and situate it in relation to the traditional animal welfare literature. We find that the core PAW literature is small (n = 10 papers) but links to wider areas of current research interest. The PAW literature is defined by four features: (1) positive emotions which is arguably the most widely acknowledged; (2) positive affective engagement which serves to functionally link positive emotions to goal-directed behavior; (3) quality of life which serves to situate PAW within the context of finding the right balance of positives over negatives; (4) happiness which brings a full life perspective to PAW. While the two first points are already part of welfare research going back decades, the two latter points could be linked to more recent research agendas concerning aggregation and how specific events may affect the ability of animals to make the best of their lives.

Environmentally enriched pigs have transcriptional profiles consistent with neuroprotective effects and reduced microglial activity

Environmental enrichment (EE) is widely used to study the effects of external factors on brain development, function and health in rodent models, but very little is known of the effects of EE on the brain in a large animal model such as the pig. Twenty-four young pigs (aged 5 weeks at start of study, 1:1 male: female ratio) were housed in environmentally enriched (EE) pens and provided with additional enrichment stimulation (a bag filled with straw) once daily. Litter, weight and sex matched controls n= (24) were housed in barren (B) conditions. Behaviour was recorded on alternate days from study day 10. After 21 days, RNA-sequencing of the frontal cortex of male piglets culled one hour after the enrichment stimulation, but not those at 4 h after stimulation, showed upregulation of genes involved in neuronal activity and synaptic plasticity in the EE compared to the B condition. This result is mirrored in the behavioural response to the stimulation which showed a peak in activity around the 1 h time-point. By contrast, EE piglets displayed a signature consistent with a relative decrease in microglial activity compared to those in the B condition. These results confirm those from rodents, suggesting that EE may also confer neuronal health benefits in large mammal models, through a potential relative reduction in neuroinflammatory process and increase in neuroprotection driven by an enrichment-induced increase in behavioural activity.

Associations between Oxytocin Receptor Gene Polymorphisms, Empathy towards Animals and Implicit Associations towards Animals

Oxytocin has been well researched in association with psychological variables and is widely accepted as a key modulator of human social behaviour. Previous work indicates involvement of oxytocin receptor gene (OXTR) single nucleotide polymorphisms (SNPs) in human-human empathy, however little is known about associations of OXTR SNPs with empathy and affective reactions of humans towards animals. Five OXTR SNPs previously found to associate with human social behaviour were genotyped in 161 students. Empathy towards animals and implicit associations were evaluated. A General Linear Model was used to investigate the OXTR alleles and allelic combinations along with socio-demographic variables and their influence on empathy towards animals. Empathy towards animals showed a significant association with OXTR SNP rs2254298; homozygous G individuals reported higher levels of empathy towards animals than heterozygous (GA). Our preliminary findings show, for the first time, that between allelic variation in OXTR and animal directed empathy in humans maybe associated, suggesting that OXTRs social behaviour role crosses species boundaries, warranting independent replication.

Up-regulation of IGF-1 in the frontal cortex of piglets exposed to an environmentally enriched arena

Environmental enrichment (EE) is widely used in the life sciences to study effects of environment on the brain. In pigs, despite lack of EE being a key welfare issue there is little understanding of brain effects of EE in pigs. This project aimed to study the effects of exposure to an EE arena on piglet behaviours and on brain gene expression levels with a focus on IGF-1 and related genes. Eight litters of large white×landrace×Hampshire piglets were farrowed and raised in a free farrowing system (PigSAFE). At 42days of age, 6pigletsperlitter were given access to an enriched arena with plentiful peat, straw and space, (in groups of 4 made up of stable pairs) for 15min per day on 5 consecutive days to allow them to habituate to the apparatus. Piglet behaviours were recorded in the arena for 15min periods on 3 consecutive days. On the final day only one pair of test piglets per litter was given access to the arena. Brain tissue was collected within 45min of the test from piglets exposed to the arena on the day and their non-exposed littermate controls. RNA was extracted from the frontal cortex and QRT-PCR for selected genes run on a Stratgene MX3005P. In both the home pen and the EE arena litters spent the largest proportion of time engaging in foraging behaviour which was significantly increased in the enriched arena (t₇=5.35, df=6, p=0.001). There were decreases in non-running play (t₇=4.82, p=0.002) and inactivity (t₇=4.6, p=0.002) in the arena. A significant fold change increase (FC=1.07, t=4.42, p=0.002) was observed in IGF-1 gene expression in the frontal cortex of piglets exposed to the enriched arena compared to those not exposed on the day of culling. No change in expression was observed in CSF1, the IGF-1 receptor gene nor in any of the binding proteins tested (IGFBP1-6). There was a weak tendency for increased expression of the neurotrophic factor BDNF1 (fold change: 1.03; t₇=1.54, p=0.1). We believe this work is the first to explore effects of EE on pig brain physiology and development, and also points to a potential role for IGF-1 in brain effects of EE.

Behavioral and physiological responses of primiparous sows to mixing with older, unfamiliar sows

Pigs are mixed into new social groups at various stages of production, and this study investigated the response of gilts to mixing with older unfamiliar sows. Four groups of 6 gilts and 1 group of 5 gilts were housed in stable groups until the most recently bred female reached d 39 of gestation. Then, stable groups were split such that 15 gilts remained in their home pens (CON) and 14 gilts were mixed (MIX) with 3 multiparous sows for 1 wk (M1), returned to the home pen for 1 wk, and then mixed with 3 different sows for 1 wk (M2). Continuous behavioral observations of gilt location in the pen, posture, aggressive, and other social interactions were made from the start of M1 and M2 for 5 h. Five-minute scans of location, posture, and behavior as well as salivary cortisol measurements were taken before, during, and after each mix week, whereas skin lesions were counted before and after each mix. During the mixed period, MIX gilts spent more (P ≤ 0.009) time in the individual feeding stalls, ventral lying, sitting, involved in aggression, and idle and less (P < 0.001) time in the straw-bedded area, lateral lying, and performing exploratory behavior (chewing, nosing, and rooting) than CON gilts. Additionally, MIX gilts had greater (P < 0.001) salivary cortisol concentrations and accumulated more (P < 0.001) skin lesions during mixing sessions compared to CON gilts. Mixed gilts in M2 spent more (P ≤ 0.013) time in the feeding stalls and ventral lying and less (P ≤ 0.029) time standing and in the dunging passageway compared to M1. Compared to M1, gilts had lower (P < 0.001) salivary cortisol concentrations and fewer (P ≤ 0.027) lesions in front and middle regions of the body during M2. During M2, salivary cortisol concentration was positively correlated with time spent in the dunging passageway (Spearman's rank correlation [rs] = 0.650, P = 0.022) and negatively correlated with time spent in the feeding stalls (rs = -0.762, P = 0.004). Results indicated that gilts adapted their behavior during M2 by using the feeding stalls more, and they became less active, especially when interacting with the sows. Despite this adaptation in M2, lesions and salivary cortisol in M IX gilts were much greater than in CON gilts, highlighting the severity of mixing gilts with multiparous sows.

Selection for 'environmentaI fit' from existing domesticated species

The selection of farm animals through breeding for human benefit has a very long history. In more recent times the practice of animal breeding has become highly sophisticated and the speed of change in 'production traits' such as rate of growth and milk yield has correspondingly increased dramatically. This narrow focus on production traits led to a number of well-documented examples of 'unfavourable' correlated responses such as negative fertility and health issues in high-yielding dairy cattle, with concerns that animal breeding is inherently antagonistic to animal welfare. In this paper the authors explore some of the questions surrounding breeding and welfare and, specifically, how to conceptualise and improve the 'fit' between the selected animal and the environment, or system, in which the animal is reared and managed. The authors conclude that there is a need for a better understanding of genotype x environment effects on health and welfare traits in order to inform the development of breeding programmes that lead to improved environmental fit in animals. They also see the need for the development of valid traits for assessing health and welfare, greater consideration of early life effects that can also potentially affect environmental fit and a need to consider the impacts of climate change on breeding programmes.

Precalving temperament and maternal defensiveness are independent traits but precalving fear may impact calf growth

Human safety can be compromised by the response of beef cows to handling or when defending their calf. However, little is known about how precalving temperament, postcalving defensiveness, and maternal care are related. The impacts of cow temperament on calf neonatal vigor and ADG are also unknown. Data were collected on 2 farms (Farm 1, n = 143, 1 parity; Farm 2, n = 237, 2 parities). Temperament was recorded before calving when restrained in a crush (crush score), on exit from the crush (flight speed), and when isolated with a handler. Defensiveness was recorded within 4 d after calving during handling of the calf. Maternal interactions with the calf and calf vigor were recorded for 3 h after calving (Farm 1 only) and ADG was measured over 7 mo. Crush score and flight speed were repeatable within a parity (range in repeatability 0.33 to 0.49; P < 0.001). Crush score (0.50; P < 0.001) and defensiveness (up to 0.71; P < 0.001) were repeatable across parities. Temperament and defensiveness were unrelated on Farm 1; on Farm 2 a fearful crush score was associated with heightened defensiveness as measured by vigorous movement during calf handling (P < 0.001). Temperament and defensiveness were unrelated to calving ease or the amount of maternal behavior shown to the calf. At Farm 1, cows that exited the crush quickly had calves with a lighter birth weight (P = 0.023) and those that were agitated when isolated had calves with a decreased ADG (P = 0.017). Defensiveness was unrelated to ADG and neither temperament nor defensiveness affected calf vigor. Cow precalving temperament and postcalving defensiveness are repeatable but appear to be independent traits, neither of which is related to maternal interactions with the neonatal calf. Reducing precalving fearfulness should not affect postcalving behavior and changing postcalving defensiveness should not affect other maternal care traits. Fearful cows may produce calves with decreased birth weight and ADG, which, if confirmed, suggests that cow fearfulness may have wider economic implications than previously realized.

Genetic associations between behavioral traits and direct-social effects of growth rate in pigs

This study examined the behavioral consequences of selecting pigs using a social genetic model for growth. Calculations enable each member of a group of pigs to be given a direct breeding value (DBV) and a social breeding value (SBV), which can be summarized into a total breeding value (TBV) for growth. Selection for growth TBV could affect animal behavior because social effects account for within-group interactions. Data were recorded from 96 groups of Yorkshire and Yorkshire × Landrace pigs in a nucleus herd. Each group contained 15 pigs fed ad libitum from 2 feeders; the space allowance was 0.85 m2/pig. Average daily gain was quantified from 35 to 100 kg of BW. Fighting and bullying activity at mixing (period 1), lying frequency 3 wk after mixing (period 2), and counts of skin lesions in periods 1 and 2 were recorded. The DBV for these traits were estimated with a classic animal model. We simulated different correlations between the direct genetic effect and the social genetic effect on growth rate (r(DS)), 2 components that respectively determine a pig's genetic capacity to grow and its genetic influence on growth of group mates: r(DS) was successively assumed to be 0 and ±0.12, ±0.20, ±0.29, and ±0.58. Finally, the correlations between DBV, SBV, and TBV for ADG, as well as the DBV for behavior and skin lesions, were calculated and tested for a level of significance at P < 0.05. The gradient from negative to positive values of r(DS) refers to a progressive path running from genetic antagonism to genetic mutualism for growth. If rDS in the population truly ranged between -0.58 and -0.20, correlations for TBV for ADG with DBV for fighting and bullying progressively increased with rDS. Consequently, if rDS was low (between -0.12 and +0.12) or positive (>+0.12), pigs with high TBV for ADG had higher DBV for bullying other pigs in the group and for fighting than pigs with lower TBV for ADG. Pigs with high TBV for ADG did not differ from other pigs in their DBV for lesions to the anterior part of the body, but they had a lower DBV for posterior lesions, whereas in period 2, they had higher DBV for posterior lesions and lower DBV for lying. Under genetic mutualism for growth and in housing conditions similar to those in the present study, selection for growth TBV would promote the rapid establishment of the dominance relationships, with more aggressive contests among group mates at mixing. Pigs would subsequently be more active but, judging by skin lesions, less willing to fight in a more stable social situation.

Board invited review: The importance of the gestation period for welfare of calves: maternal stressors and difficult births

The prenatal period is of critical importance in defining how individuals respond to their environment throughout life. Stress experienced by pregnant females has been shown to have detrimental effects on offspring biology in humans and a variety of other species. It also is becoming increasingly apparent that prenatal events can have important consequences for the behavior, health, and productivity of offspring in farmed species. Pregnant cattle may experience many potentially important stressors, for instance, relating to their social environment, housing system and physical environment, interactions with humans and husbandry procedures, and their state of health. We examined the available literature to provide a review of the implications of prenatal stress for offspring welfare in cattle. The long-term effects of dystocia on cattle offspring also are reviewed. To ensure a transparent and repeatable selection process, a systematic review approach was adopted. The research literature clearly demonstrates that prenatal stress and difficult births in beef and dairy cattle both have implications for offspring welfare and performance. Common husbandry practices, such as transport, were shown to influence offspring biology and the importance of environmental variables, including thermal stress and drought, also were highlighted. Maternal disease during pregnancy was shown to negatively impact offspring welfare. Moreover, dystocia-affected calves suffer increased mortality and morbidity, decreased transfer of passive immunity, and important physiological and behavioral changes. This review also identified considerable gaps in our knowledge and understanding of the effects of prenatal stress in cattle.

Assessing pig body language: agreement and consistency between pig farmers, veterinarians, and animal activists

This study investigates the interobserver and intraobserver reliability of qualitative behavior assessments (QBA) of individual pigs by 3 observer groups selected for their diverging backgrounds, experience, and views of pigs. Qualitative behavior assessment is a "whole animal" assessment approach that characterizes the demeanor of an animal as an expressive body language, using descriptors such as relaxed, anxious, or content. This paper addresses the concern that use of such descriptors in animal science may be prone to distortion by observer-related bias. Using a free-choice profiling methodology, 12 pig farmers, 10 large animal veterinarians, and 10 animal protectionists were instructed to describe and score the behavioral expressions of 10 individual pigs (sus scrofa) in 2 repeat sets of 10 video clips, showing these pigs in interaction with a human female. They were also asked to fill in a questionnaire gauging their experiences with and views on pigs. Pig scores were analyzed with generalized procrustes analysis and effect of treatment on these scores with ANOVA. Questionnaire scores were analyzed with a χ(2) test or ANOVA. Observers achieved consensus both within and among observer groups (P < 0.001), identifying 2 main dimensions of pig expression (dim1: playful/confident-cautious/timid; dim2: aggressive/nervous-relaxed/bored), on which pig scores for different observer groups were highly correlated (pearson r > 0.90). The 3 groups also repeated their assessments of individual pigs with high precision (r > 0.85). Animal protectionists used a wider quantitative range in scoring individual pigs on dimension 2 than the other groups (P < 0.001); however, this difference did not distort the strong overall consistency of characterizations by observers of individual pigs. Questionnaire results indicated observer groups to differ in various ways, such as daily and lifetime contact with pigs (P < 0.001), some aspects of affection and empathy for pigs (P < 0.05), and confidence in the validity of personal QBA descriptors (P < 0.02). The main finding of this study is that despite such differences in background and outlook, the 3 observer groups showed high interobserver and intraobserver reliability in their characterizations of pig body language. This supports the empirical nature of QBA in context of the wider anthropomorphism debate.

Qualitative Behavioural Assessment of emotionality in pigs

Scientific assessment of affective states in animals is challenging but vital for animal welfare studies. One possible approach is Qualitative Behavioural Assessment (QBA), a ‘whole animal’ methodology which integrates information from multiple behavioural signals and styles of behavioural expression (body language) directly in terms of an animal's emotional expression. If QBA provides a valid measure of animals’ emotional state it should distinguish between groups where emotional states have been manipulated. To test this hypothesis, QBA was applied to video-recordings of pigs, following treatment with either saline or the neuroleptic drug Azaperone, in either an open field or elevated plus-maze test. QBA analysis of these recordings was provided by 12 observers, blind to treatment, using a Free Choice Profiling (FCP) methodology. Generalised Procrustes Analysis was used to calculate a consensus profile, consisting of the main dimensions of expression. Dimension one was positively associated with terms such as ‘Confident’ and ‘Curious’ and negatively with ‘Unsure’ and ‘Nervous’. Dimension two ranged from ‘Agitated’/‘Angry’ to ‘Calm’/‘Relaxed’. In both tests, Azaperone pre-treatment was associated with a more positive emotionality (higher scores on dimension one reflecting a more confident/curious behavioural demeanour) than control pigs. No effect of drug treatment on dimension two was found. Relationships between qualitative descriptions of behaviour and quantitative behavioural measures, taken from the same recordings, were found. Overall, this work supports the use of QBA for the assessment of emotionality in animals.

Dairy cow feeding space requirements assessed in a Y-maze choice test

The effect of proximity to a dominant cow on a low-ranking cow's willingness to feed was assessed using choice tests. The main aim of the experiment was to determine the feeding space allowance at which the majority of subordinate cows would choose to feed on high-palatability food (HPF) next to a dominant cow rather than feeding alone on low-palatability food (LPF). Thirty Holstein-Friesian cows were used in the study. Half of the cows were trained to make an association between a black bin and HPF and a white bin and LPF, and the other half were trained with the opposite combination. Observations of pair-wise aggressive interactions were observed during feeding to determine the relative social status of each cow. From this, dominant and subordinate cows were allocated to experimental pairs. When cows had achieved an HPF preference with an 80% success rate in training, they were presented with choices using a Y-maze test apparatus, in which cows were offered choices between feeding on HPF with a dominant cow and feeding on LPF alone. Four different space allowances were tested at the HPF feeder: 0.3, 0.45, 0.6, and 0.75 m. At the 2 smaller space allowances, cows preferred to feed alone (choices between feeding alone or not for 0.3- and 0.45-m tests were significantly different). For the 2 larger space allowances, cows had no significant preferences (number of choices for feeding alone or with a dominant). Given that low-status cows are willing to sacrifice food quality to avoid close contact with a dominant animal, we suggest that the feeding space allowance should be at least 0.6m per cow whenever possible. However, even when space allowances are large, it is clear that some subordinate cows will still prefer to avoid proximity to dominant individuals.

Pre-natal social stress and post-natal pain affect the developing pig reproductive axis

This study assessed the effect of pre-natal social stress and post-natal pain on the reproductive development of young (approximately day 40) pigs. Male pigs carried by sows that were stressed by mixing with unfamiliar older sows for two 1-week periods during mid-pregnancy had lower plasma testosterone (0.54 vs 0.86 ng/ml, s.e.d.=0.11; P=0.014) and oestradiol (E2; 22.9 vs 38.7 pg/ml, s.e.d.=7.80; P=0.021) concentrations compared with males carried by unstressed control sows. Although there was no effect of pre-natal stress on female E2 concentrations, female pigs carried by stressed sows had fewer primordial ovarian follicles (log −4.32/μm2 vs −4.00/μm2, s.e.d.=0.136; P=0.027). Tail amputation on day 3 after birth reduced E2 concentrations in female (4.78 vs 6.84 pg/ml, s.e.d.=0.86; P=0.03) and in male (25.6 vs 34.9 pg/ml, s.e.d.=3.56; P=0.021) pigs and reduced both testis weight (0.09% of body weight vs 0.10% of body weight, s.e.d.=0.003; P=0.01) and the percentage of proliferating Leydig cells (1.97 vs 2.12, s.e.d.=0.114; P=0.036) compared with sham-amputated littermate controls. There was a significant (P=0.036) interaction between the effects of pre-natal stress and post-natal pain on testicular expression of the steroidogenic enzyme 17α-hydroxylase, such that amputation increased expression in pigs born to control sows, but reduced expression in animals born to stressed sows. This study shows that stressful procedures associated with routine animal husbandry can disrupt the developing reproductive axis.

The impact of prenatal stress on basal nociception and evoked responses to tail-docking and inflammatory challenge in juvenile pigs

The consequences of tail-docking (at 2-4 days) and prenatal stress (maternal social stress during the 2nd third of pregnancy) on baseline nociceptive thresholds and responses to acute inflammatory challenge were investigated in juvenile pigs in two studies. Nociceptive thresholds were assessed on the tail root and on the hind foot using noxious mechanical and cold stimulation before and after acute inflammatory challenge by intradermal injection of 30 μg capsaicin (study 1) or 3% carrageenan (study 2) into the tail root. Four groups of 8 (study 1, n=14-16 pigs/treatment) or 5 (study 2, n=6 pigs/treatment/sex) week-old pigs were exposed to the main factors: maternal stress and treatment (docked vs. intact tails). In study 1, tail docking did not significantly alter thresholds to noxious mechanical stimulation, whilst prenatally stressed pigs had significantly higher baseline thresholds to noxious mechanical stimulation on the tail root and on the hind foot than unstressed pigs, whether tail-docked or intact. Capsaicin injection induced localised mechanical allodynia around the tail root in all treatment groups, but had no effect on noxious plantar mechanical responses; however prenatally stressed offspring exhibited significantly attenuated response thresholds to capsaicin compared to controls. In study 2 tail docking did not alter thresholds to either mechanical or noxious cold stimulation. Baseline response durations to noxious cold stimulation of the tail root were significantly shorter in both sexes of prenatally stressed pigs, whilst male but not female prenatally stressed pigs exhibited significantly higher baseline thresholds to mechanical stimulation than controls, although results in female pigs tended towards significance. Carrageenan injection into the tail root induced localised mechanical and cold allodynia in all treatment groups, effects that were attenuated in prenatally stressed pigs. Collectively, these findings indicate that prenatal stress can induce long-term alterations in nociceptive responses, manifest as a reduced sensitivity to noxious mechanical and cold stimulation and evoked inflammatory allodynia. Neonatal tail-docking does not lead to long-term alterations in nociception in pigs.

Genetic parameters of piglet survival and birth weight from a two-generation crossbreeding experiment under outdoor conditions designed to disentangle direct and maternal effects

Multivariate Bayesian linear-threshold models were used to estimate genetic parameters of peri- and postnatal piglet survival and individual birth weight of piglets reared under outdoor conditions. Data of 21,835 individual piglet observations were available from a 2-generation crossbreeding experiment selected for direct and maternal genetic effects of postnatal piglet survival on piglet and dam levels, respectively. In the first generation, approximately one-half of the Landrace sires used were selected for large or average breeding values of maternal genetic effects on postnatal piglet survival, whereas in the second generation the Large White sires used were selected for direct genetic effects of the same trait. Estimates of direct and maternal heritability were 0.21 and 0.15, 0.24 and 0.14, and 0.36 and 0.28 for piglet survival at birth and during the nursing period, and individual birth weight, respectively. In particular, direct heritabilities are substantially larger than those from the literature estimated for indoor-reared piglets, suggesting that genetic effects of these traits are substantially greater under outdoor conditions. Direct or maternal genetic correlations between survival traits or with birth weight were small (ranging from 0.06 to 0.17), indicating that peri- and postnatal survival are genetically under rather different control, and survival was only slightly positively influenced by birth weight. There were significant (P < 0.05) negative genetic correlations between direct and maternal genetic effects within each of the analyzed traits ranging from -0.36 to -0.45, which have to be considered when selecting for piglet survival. Adjustment of traits for litter size or inclusion of genetic groups showed insignificant effects on the magnitude of the estimated genetic parameters. The magnitude of genetic parameters suggested that there is substantial potential for genetic improvement of survival traits and birth weight in direct and maternal genetic effects, especially when piglets are kept under outdoor conditions.

Genetic validation of postmixing skin injuries in pigs as an indicator of aggressiveness and the relationship with injuries under more stable social conditions

The objective of the study was to estimate genetic correlations between skin lesions and aggressive behavior postmixing and under more stable social conditions as a potential means of selecting against pig aggressiveness. Postmixing aggression in commercial pig production is common, compromises welfare and profitability, and cannot be significantly reduced by low-cost changes to the environment. A genetic component to individual aggressiveness has been described in pigs and other species. Selective breeding against aggressiveness ought to be possible if an easily measured indicator trait can be shown to be genetically associated with aggressive behavior. Aggressive behavior was recorded continuously for 24 h after mixing, and a count of skin lesions (lesion count, LC) was recorded at 24 h and 3 wk postmixing on 1,663 pigs. Two behavioral traits were found to have a moderate to high heritability similar to that of growth traits; duration of involvement in reciprocal fighting (0.43 +/- 0.04) and delivery of nonreciprocal aggression (NRA; 0.31 +/- 0.04), whereas receipt of NRA had a lower heritability (0.08 +/- 0.03). Genetic correlations (r(g)) suggested that lesions to the anterior region of the body 24 h after mixing were associated with reciprocal fighting (r(g) = 0.67 +/- 0.04), receipt of NRA (r(g) = 0.70 +/- 0.11), and to a lesser extent, delivery of NRA (r(g) = 0.31 +/- 0.06). Lesions to the center and rear were primarily genetically associated with receipt of NRA (r(g) = 0.80 +/- 0.05, 0.79 +/- 0.05). Genetic correlations indicated that pigs that engaged in reciprocal fighting delivered NRA to other animals (r(g) = 0.84 +/- 0.04) but were less likely to receive NRA themselves (r(g) = -0.41 +/- 0.14). A genetic merit index using lesions to the anterior region as one trait and those to the center or rear or both as a second trait should allow selection against animals involved in reciprocal fighting and the delivery of NRA. Positive correlations between LC 24 h and 3 wk after mixing were found, especially for lesions to the center and rear of the body, indicating that postmixing lesions are predictive of those received under more stable group conditions. As well as reducing immediate aggression at mixing, selection on postmixing LC is expected to have a long-term impact on injuries from aggression, even after dominance relationships are established.

Pre-natal stress amplifies the immediate behavioural responses to acute pain in piglets

Pre-natal stress (PNS) or undernutrition can have numerous effects on an individual's biology throughout their lifetime. Some of these effects may be adaptive by allowing individuals to tailor their phenotype to environmental conditions. Here we investigated, in the domestic pig Sus scrofa, whether one possible consequence of a predicted adverse environment could be altered pain perception. The behavioural response of piglets to the surgical amputation ('docking') of their tail or a sham procedure was measured for 1 min in piglets born to mothers who either experienced mid-gestation social stress or were left undisturbed throughout pregnancy. A behavioural pain score was found to predict the docked status of piglets with high discriminant accuracy. Piglets exposed to PNS had a significantly higher pain score than controls, and for each litter of tail-docked piglets, the average pain score was correlated with mid-gestation maternal cortisol levels. The data presented here provide evidence that the experience of stress in utero can result in a heightened acute response to injury in early life. Speculatively, this may represent an adaptive alteration occurring as a consequence of a pre-natal 'early warning' of environmental adversity.

Early weaning results in less active behaviour, accompanied by lower 5-HT1A and higher 5-HT2A receptor mRNA expression in specific brain regions of female pigs

In rodents and humans stressful events in early life e.g. maternal deprivation, can increase sensitivity to stress in later life. Humans may become more susceptible to mood disorders, e.g. depression. In livestock species, such as pigs, early weaning is a form of maternal deprivation. We investigated behavioural consequences in 99 female pigs weaned at three different ages (12, 21 and 42 days; d12, d21, d42). Pigs were habituated to an open field arena over 6 days before being given 5-min open-field tests over three subsequent days (days 77-79). Early-weaned pigs (d12) showed behavioural inhibition (reduced vocalisations and lower activity) compared with later-weaned pigs, although in all groups these measures declined over the three tests, so this treatment difference might reflect more rapid habituation to the test in d12 pigs. Long-term effects on mood-related 5-HT receptor subtypes were measured in the brain at 90 days in a random sample of the d12 (n=8) and d42 pigs (n=8), using (3)H-ligand-binding and autoradiography and in situ hybridisation histochemistry. There were no differences between weaning ages in binding of (3)H-8-OH-DPAT (5-HT(1A) receptor agonist) or of (3)H-ketanserin (5-HT(2A) receptor antagonist) to any brain region studied. In d12 pigs, 5-HT(1A) receptor mRNA expression per unit area was 29%, 63%, 52% and 64% lower than in d42 pigs in the parvocellular PVN, amygdala and hippocampal dentate gyrus and pyramidal cell layer, respectively. The ratio of expression per cell to expressing cells per unit area was also lower, by 31%, in the pars horizontalis of the PVN in d12 pigs. Conversely, 5-HT(2A) receptor mRNA was expressed at a 25% and 28% higher density per unit area in the amygdala and pyramidal cell layer of the hippocampus, respectively, in these d12 pigs. In individual pigs, across brain regions, 5-HT(1A) receptor mRNA data were 70-79% correlated with binding data but no correlation was found for 5-HT(2A) data, suggesting different regulatory mechanisms. The behavioural and neurobiological responses to early weaning might represent either dysfunction or adaptation. Further investigation is required.

Investigating the behavioural and physiological indicators of neonatal survival in pigs

Survival is reduced in low birth weight piglets, which display poor thermoregulatory abilities and are slow to acquire colostrum. Our aim was to identify additional behavioural and physiological indicators of piglet survival incorporating traits reflective of both the intrauterine and extrauterine environment. Data were collected from 135 piglets from 10 Large White x Landrace sows to investigate which physiological measurements (e.g. individual placental traits), and which behavioural measurements (e.g. the quantification of piglet vigour), were the best indicators of piglet survival. Generalised linear models confirmed piglet birth weight as a critical survival factor. However, with respect to stillborn mortality, piglet shape and size, as measured by ponderal index (birth weight/(crown-rump length)(3)), body mass index (birth weight/(crown-rump length)(2)), respectively, and farrowing birth order were better indicators. With respect to live-born mortality, postnatal survival factors identified as crucial were birth weight, vigour independent of birth weight, and the latency to first suckle. These results highlight the importance of the intrauterine environment for postnatal physiological and behavioural adaptation and identify additional factors influencing piglet neonatal survival.

The responses of growing pigs to a chronic-intermittent stress treatment

Many of the stressor treatments used in animal models of depression have parallels in the normal experiences of domestic pigs. The experiment described here aimed to assess whether a chronic-intermittent stress regime caused behavioural or physiological changes, indicative of depression, in domestic pigs. Ten juvenile male pigs were exposed to a social and environmental stress regime. Over the stressor period, weight gain was significantly lower in test pigs than in control pigs. Stress treatment had a significant effect on salivary cortisol levels, with test pigs having a higher salivary cortisol concentration than control pigs after the stress treatment but not before. Test pigs showed less ventral lying than control pigs in the post-stress observation. A detrended fluctuation analysis (DFA) of postural behavioural organisation showed that test pigs had a more structured pattern of activity than controls in the post-stress observation and a tendency towards a more structured pattern in the pre-stress observation. There were no major behavioural differences between the two groups during three repeated open field tests. The results suggest that the stressor treatment did create a mild chronic stress, as indicated by the hypercortisolaemia and lower weight gain in the test pigs. However, no unambiguous behavioural indicators of depression were seen. The behavioural analysis did show that fractal techniques, such as DFA, could be applied to pig behaviour and that they can reveal extra novel information about the structure of an individual's behavioural organisation and how it changes in response to complex environmental stressors.

Housing System, Milk Production, and Zero-Grazing Effects on Lameness and Leg Injury in Dairy Cows

The aim of this study was to assess the effect of grazing (G) vs. zero-grazing (ZG), level of milk production, and quality and type of housing system [free stalls (FS) and straw yards (SY)] on the prevalence of lameness and leg injuries in dairy cows. Observations were made on 37 commercial dairy farms across Great Britain. A single visit of 5 d duration was made to each farm. During this visit, lameness scores and the incidence of swellings, rubs, and injuries to hocks and knees were recorded on all the peak- or mid-lactation cows. Aspects of the quality of housing and management that were likely to affect foot and leg health were recorded. There were more lame cows on ZG farms (39 +/- 0.02%) than on grazing (G) farms (15 +/- 0.01%), and lameness scores were higher on FS farms compared with SY farms (0.25 +/- 0.01 vs. 0.05 +/- 0.01). Cows on SY farms had fewer hock and knee injuries compared with FS farms. The frequency of knee swellings was higher on ZG farms (0.31 +/- 0.02) than on G farms (0.15 +/- 0.01). Aspects of the free-stall design affected foot and leg health. The number of hock swellings increased with increasing stall gradient (0.16 +/- 0.01 with no slope vs. 0.39 +/- 0.02 at a 0 to 1.5% slope). There was an interaction between the length of the free-stall lunging space and the hip width of the cow, indicating that the incidence of lameness is generally highest on farms with small free stalls and heavy cows. High levels of milk production did not affect lameness or leg injury. The results indicate that housing cows throughout the year potentially has a detrimental effect on foot and leg health. However, good free-stall design may reduce lameness and leg lesions.

The effect of confinement during lactation on the hypothalamic–pituitary–adrenal axis and behaviour of primiparous sows

Commercial sows are typically confined in crates before and during parturition and remain there throughout lactation. In various animal species including non-lactating pigs, confinement over similar periods leads to adaptive changes in the HPA axis, consistent with chronic stress. To investigate evidence for chronic stress in lactating sows, primiparous sows (gilts) were kept in behaviourally confining crates with straw bedding (CS, n = 8) or without bedding (C, n = 8) or in larger strawed pens (PS, n = 16) between 5 days before parturition until 29 days postpartum (piglets were weaned on day 28). Behavioural and physiological recordings (Plasma ACTH and cortisol) were taken at intervals (baseline), and CRH injections were given on five occasions (days 2, 8, 15, 22 and 29 postpartum). The PS gilts spent more time in substrate-directed behaviour and lying ventrally, and less time lying laterally and sitting than the two crated treatments (C and CS) throughout lactation. Baseline plasma ACTH and cortisol levels showed no treatment differences, although we confirmed that a diurnal pattern exists, with morning (1000 h) cortisol being higher than later in the day. CRH challenge tests suggested changes in the HPA axis, consistent with chronic stress, by the end of the lactation period. Cortisol response to CRH tended to be higher in CS than PS across all days, and by day 29 cortisol response to CRH was significantly higher in CS compared to PS and tended to be higher in C than PS. Cortisol/ACTH ratio following CRH challenge also tended to be higher in the crate treatments (C and CS) by day 29. These data suggest that prolonged confinement in farrowing crates may have a negative impact on sow welfare.

Programming the offspring of the pig by prenatal social stress: neuroendocrine activity and behaviour

This study provides evidence in the pig that stress experienced during gestation has long-lasting effects on offspring daughters, including their maternal behaviour. Thirty-six primiparous sows were divided into control and two groups that were stressed (by social mixing) during either the second (Mix 2) or third (Mix 3) trimester of pregnancy. We found detrimental effects of mixing on the mothers' growth, body lesions, and cortisol secretion, but did not observe any significant effects on reproductive parameters including birth weight. At 60 days of age, 48 daughters were randomly selected from the three treatments: half were challenged using a restraint and isolation test. Then, all were culled and brain tissue was collected. In situ hybridisation measurements showed increased expression of CRH mRNA in the PVN in unrestrained Mix 2 and in the amygdala of Mix 2 and Mix 3 daughters. At 67 days, 24 further daughters were mixed to measure their responses to this social stress. All showed increased salivary cortisol secretion, but Mix 2 and Mix 3 daughters showed a greater and longer response than controls. Finally, all 24 were inseminated and at parturition maternal behaviour was measured. Mix 2 and Mix 3 daughters were more restless and more responsive to piglets that approached the head of the sow, traits which previously have been shown to be a component of abnormal maternal behaviour. Indeed, Mix 2 and Mix 3 daughters also tended to bite at their piglets more than control daughters.

Resident-intruder trait aggression is associated with differences in lysine vasopressin and serotonin receptor 1A (5-HT1A) mRNA expression in the brain of pre-pubertal female domestic pigs (Sus scrofa)

Aggressive behaviour exhibited by domestic pigs following encounters with unfamiliar individuals is a serious welfare and economical problem. Aggression resulting in skin lesions is similarly prevalent in prepubertal pigs of either sex. Little is known about the neural circuits and neuropeptides that control aggression in the pig. Because there is evidence for the involvement of the vasopressin and serotonergic systems in the regulation of aggressive behaviour in male mammals, we sought differences using quantitative in situ hybridisation of vasopressin and serotonin 1A receptor (5-HT1A) mRNA expression within specific brain regions of aggressive and nonaggressive prepubertal female pigs. The number of cells expressing vasopressin mRNA was significantly higher in aggressive pigs in the medial amygdala, lateral septum (LS) and showed a similar trend in the bed nucleus of the stria terminalis (BnST) but not the paraventricular nucleus (PVN) or supraoptic nucleus. The 5-HT1A receptor was widely expressed through the porcine brain and a significantly lower intensity (silver grain density) of 5-HT1A mRNA expression was observed in the BnST. In the medial amygdala and LS fewer cells expressed 5-HT1A mRNA in aggressive pigs but no differences were found in the PVN. In the absence of inbred strains or selection lines, these findings have shown that prior identification of phenotypic behavioural extremes in a population in advance of neural studies is a useful technique. Moreover, these findings support a central role for vasopressin and serotonin in the mediation of high trait aggression in prepubertal female pigs.