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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. 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. 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.

• The sow's role beyond nutrition is, in commercial pig production, largely ignored. • We investigated how maternal characteristics contribute to offspring outcomes. • Sows with lower cortisol concentrations showed better nursing behaviour. • Piglets from sows with lower cortisol concentrations grew better. • Reducing sow stress during lactation improves sow and piglet performance and welfare. 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. [ABSTRACT FROM AUTHOR]

Qualitative behaviour assessment is an integrative methodology that characterizes behaviour as a dynamic, expressive body language (e.g. as anxious or content). Such assessments are sensitive to environmental context, which makes them informative but also vulnerable to observers'' biased views of that context. This study investigated whether and how perceived environmental background affects observers'' qualitative assessments of pig, Sus scrofa, behaviour. Fifteen growing pigs were filmed individually against a neutral background while interacting with a novel object. The footage of each pig was digitally isolated from that background and pasted against indoor and outdoor backgrounds filmed in real time. The 30 video clips thus obtained were shown to 16 observers, who were led to believe these were 30 different pigs filmed in either an indoor or an outdoor pen. Free-choice profiling was used to instruct observers in qualitative behaviour assessment, and data were analysed with generalized Procrustes analysis. Analysis of variance found a significant effect of environmental background on pig scores on the second consensus dimension (confident/content–cautious/nervous), but not on the first (playful/active–bored/lethargic). However, 95% confidence intervals and indexes for the variability attributable to environmental background, calculated for both consensus dimensions, indicated that any such effects should be relatively small. High correlations were found between indoor and outdoor pig scores on both consensus dimensions (r ≥0.95). Together these results suggest that environmental background may slightly shift, but is unlikely to seriously distort, observer characterizations of pig expression. Last, we discuss possible strategies for reducing the effect of contextual bias on qualitative behaviour assessment. [Copyright &y& Elsevier]

Piglet-directed aggression by farrowing pigs seriously threatens the welfare of the piglets and also results in economic waste within the pig industry. Pre-weaning piglet mortality in the UK is around 11% with savaging accounting for up to 25% of deaths. The aim of this study was to investigate whether gilts that savage piglets behave differently to non-savaging gilts during the expulsive phase of parturition. The behaviour of the gilts during the 8 h following the birth of the first piglet was recorded. The gilts were categorised as savagers (n=4) or non-savagers (n=15) depending on their response to piglets during farrowing, and then behaviour during farrowing was compared between the two groups. The maternal behaviour during the first 8 h of farrowing differed significantly between the savagers and non-savagers. Savaging gilts were significantly more restless and more responsive towards their piglets during farrowing as characterised by increased posture changing, higher frequency of walking and time spent investigating piglets that approached their head. Overall the results of this study suggest that aberrant maternal behaviour during farrowing involves increased restlessness and responsiveness to piglets, particularly in the early stages of the expulsive phase, which are opposite to the inactivity and passivity suggested to reflect good maternal care in the pig. It is suggested that this restlessness and responsiveness of savaging gilts may not necessarily reflect poor maternal ability, but may be related to the individual’s inability to cope with restrictive environments around farrowing. [Copyright &y& Elsevier]

Abstract: The consequences of tail-docking (at 2–4days) 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 30μg 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. [Copyright &y& Elsevier]

Abstract: Wild pigs (Sus scrofa) are only territorial during the peri-parturient period and when young compete for access to teats. In other species, territorial defence is affected by contextual factors including resource quality. Territoriality could be stimulated in species such as pigs by artificial mixing and intensive housing. Test pigs were introduced to a novel opponent for 5min on consecutive days (days 1 and 2) in two locations (home pen of the test pig (P) or a neutral arena (A)) in a randomised block design. On day 1, animals tested in their home pen were more likely to initiate an escalated attack (proportion of pigs 0.43 vs 0.19 in the pen and neutral arena, P <0.01). A shorter latency to attack on day 2 in the PP (pen on both days) and PA (pen then arena) treatments suggested that a previous encounter in the home pen affected later aggressiveness. The time spent engaged in non-escalated aggressive behaviours (parallel walking, pushing, knocking and biting) with the opponent was similar in the two environments. Some capacity for territorial defence through escalated aggression and the enhancement of subsequent aggressiveness appears to occur in pigs when in their home pen. The suppression of escalated aggression in the neutral arena by handling and environmental exploration cannot be discounted, but appears not to have affected the occurrence of non-escalated aggression. The mixing of pigs in an occupied pen is likely to enhance escalated aggression from the occupants without reducing that from the intruders and should be avoided. [ABSTRACT FROM AUTHOR]

In animals, including humans, free access to high-quality (generally energy-dense) food can result in obesity, leading to physiological and health problems. Consequently, various captive animals, including laboratory and companion animals and certain farm animals, are often kept on a restricted diet. Quantitative restriction of food is associated with signs of hunger such as increases in feeding motivation, activity and redirected oral behaviours which may develop into stereotypies. An alternative approach to energy intake restriction is to provide more food, but of a reduced quality. Such alternative diets are usually high in fibre and have lower energy density. The benefits of these alternative diets for animals are controversial: some authors argue that they result in more normal feeding behaviour, promote satiety and so improve animal welfare; others argue that ‘metabolic hunger’ remains no matter how the restriction of energy intake and weight gain is achieved. We discuss the different arguments behind this controversy, focusing on two well-researched cases of food-restricted farmed livestock: pregnant sows and broiler breeders. Disagreement between experts results from differences in assumptions about what determines and controls feeding behaviour and food intake, from the methodology of assessing animal hunger and from the weighting placed on ‘naturalness’ of behaviour as a determinant of welfare. Problems with commonly used behavioural and physiological measures of hunger are discussed. Future research into animal feeding preferences, in particular the relative weight placed on food quantity and quality, would be valuable, alongside more fundamental research into the changes in feeding physiology associated with alternative diets. [Copyright &y& Elsevier]

Summary: 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 3H-ligand-binding and autoradiography and in situ hybridisation histochemistry. There were no differences between weaning ages in binding of 3H-8-OH-DPAT (5-HT1A receptor agonist) or of 3H-ketanserin (5-HT2A receptor antagonist) to any brain region studied. In d12 pigs, 5-HT1A 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-HT2A 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-HT1A receptor mRNA data were 70–79% correlated with binding data but no correlation was found for 5-HT2A data, suggesting different regulatory mechanisms. The behavioural and neurobiological responses to early weaning might represent either dysfunction or adaptation. Further investigation is required. [Copyright &y& Elsevier]

Abstract: Post-mixing aggression in commercially housed pigs can be intense and often results in the accumulation of skin lesions. The number of lesions (lesion score, LS) has often been used as a proxy indicator of post-mixing aggression. There has been no previous attempt to quantify the role of different behaviours in the accumulation of lesions. The objective of this work was to investigate the factors that contribute to LS in order to assess the validity of LS as a measure of individual aggressiveness. After mixing into new groups of 12, the durations of reciprocal fighting and bullying, the proportions of fights initiated, won and lost and physical attributes of the pigs were investigated for their impact on LS using multiple regression on a sample of 342 growing pigs. Pig liveweight was the single greatest determinant of LS. The duration spent in reciprocal fighting and being bullied were also significant determinants of the LS and contributed to the total LS in proportions of 0.17 and 0.14, respectively. The proportion of fights initiated, won and lost did not influence the LS for pigs of a given weight. On an individual pig basis, it was impossible to establish the relative importance of reciprocal fighting and the receipt of bullying to the accumulation of lesions by reference to the total LS alone. Engagement in reciprocal fighting was found to result in lesions to the anterior third of the body, whilst the receipt of bullying resulted in lesions accruing on the caudal third of the body. Reference to the location of lesions, in addition to their number, is a refinement of the methodology that potentially allows discrimination of pigs that accumulate lesions as a result of reciprocal fighting or receipt of bulling. A partial replication of the experiment at a second unit (n =84 pigs) with different genotypic, environmental and husbandry conditions confirmed that the duration spent in reciprocal fighting and being bullied were significant determinants of the LS and that the LS approach is applicable across units. Liveweight was not recorded at Unit 2. These results suggest that the LS methodology provides a rapid means of estimating aggressive behavioural phenotypes when reference is made to both the number and location of lesions and pig weight and pen identity effects are accounted for. [Copyright &y& Elsevier]