The aquaculture industry is growing rapidly, prompting an increased focus on improving the welfare of fish. While meeting physical, psychological, and behavioural needs remains a priority, the concept of resilience offers a deeper approach, moving beyond need fulfilment to actively enhance the capacity of fish to adapt, recover, and thrive. This scoping review assessed the evidence for resilience building in farmed fish through two forms of environmental enrichment: physical exercise and stressor predictability training. These enrichment types are described in terms of three key mechanisms involved in building resilience: coping with stress, cognitive flexibility, and behavioural adaptability. Exercise, particularly at moderate levels, can help regulate stress responses, promote neuroplasticity, and encourage positive social behaviours. Stressor predictability can also reduce the magnitude of stress responses and support proactive coping strategies by allowing fish to anticipate and prepare for environmental challenges. The relationship between resilience and fish welfare was also examined, highlighting the potential of these approaches as welfare management tools for aquaculture. The effectiveness of such interventions is likely to be species- and context-dependent, with outcomes influenced by how fish perceive and experience environmental conditions and practical constraints of large-scale aquaculture systems. However, integrating resilience-building strategies into aquaculture practices may not only enhance welfare but also improve production efficiency and economic performance, helping the industry meet societal expectations and long-term sustainability goals.

We discuss the intricate relationship between the evolution of the concept of stress and the development of the concept of animal welfare. After a brief review of the main concepts of animal welfare, we analyse important steps in the evolution of the concept of stress, starting from the mechanistic approach of the General Adaptation Syndrome to the recent integrative allostatic theory. We show how, over time, each concept of stress has informed the development of the concept of animal welfare. We discuss the role of emotions and affective states in the response of animals to challenges and how psychological stress is integral to the welfare of animals. Lastly, we discuss briefly the potential role of the gut-brain axis in both the concept of stress and the concept of welfare.

BACKGROUND: Normalization of data obtained from RT-qPCR studies is important for accurate interpretation of the results. The two most common methods of normalization that are used are the reference gene method or an algorithm-only approach, such as NORMA-Gene. Here, we assessed the impact of normalization using reference genes or the NORMA-Gene method on the expression results of five target genes that are related to oxidative stress (CAT, GPX1, GPX3, PRDX1, and SOD1) in the liver of sheep that had been exposed to three dietary treatments. RESULTS: The reference genes selected as the most stable across samples for normalization were HPRT1, HSP90AA1, and B2M. Interpretation of the effect of the treatment on the expression of GPX3 differed significantly between the methods of normalization. NORMA-Gene was better at reducing the variance in the expression of the target genes than was any of the other normalization methods. CONCLUSIONS: We demonstrated that NORMA-Gene can provide a more reliable normalization method that requires less resources than the use of reference genes for studies on gene expression in livestock.

Enhancing stress resilience through the early life period in pigs could potentially improve pork quality. It was hypothesised that pigs receiving maternal contact or positive human contact during lactation would have improved carcass and pork quality. Seventy-nine mixed-sex pigs were selected from a 2 × 2 factorial randomised block design for treatments maternal contact (MC+) / reduced maternal contact (MC-); and positive human contact (HC+) / control (HC-). Modified farrowing crates were utilised to reduce maternal contact (MC-). Litters in the HC+ treatment received five minutes of daily positive human interaction (stroking). Treatments ceased at 22 days of age (weaning) and pigs were slaughtered after 21 weeks of age. The m. longissimus thoracis et lumborum pH was higher in HC+ than HC- pigs (P < 0.05) during chilling, from 90 min post slaughter. No HC effects (P > 0.05) were observed for cortisol or haptoglobin concentration, hot carcass weight, P2 backfat, carcass scratches, colour, drip loss, cook loss and shear force. MC+ tended (P < 0.086) to increase carcass weight, P2 and carcass scratch score compared to MC-, but no further impacts were observed. The impact of positive human contact during early life was observed 20+ weeks after treatment with reduced pH decline, potentially indicating a reduction in pre-slaughter stress, however there were no further impacts on pork quality. There is evidence that maternal contact is important for lifetime growth performance of pigs but the impacts on stress resilience are less apparent.

The welfare of an animal is largely determined by the transient state within them that relates to what they experience. We evaluated candidate biomarkers of mental state and experience from human biomedicine as possible welfare biomarkers for sheep using a metabolic energy discrepancy model. The metabolic status of female Merino sheep was altered over three periods to induce changes in their experience and coping capacity. The first group was fed at maintenance for all periods (n = 11); the second group was fed above maintenance in period 1, at maintenance in period 2, and below maintenance in period 3 (n = 12); and the third group was fed below maintenance in period 1, at maintenance in period 2, and above maintenance in period 3 (n = 11). An isolation box test was used at the start and end of each feed period to assess the coping capacity of each sheep. Our results indicated that two of the five candidate biomarkers, insulin-like growth factor 1 and thiol oxidation, were associated with positive and negative experiences in the sheep, respectively. Future research should validate these biomarkers in sheep with other testing paradigms and in other ruminant species.

Carbon dioxide (CO2) systems stun pigs with minimal handling and physical restraint, however, they do not induce instant insensibility and pigs' aversion to CO2 has the potential to cause distress, raising animal welfare concerns. The aim of this study was to understand the factors that may influence the response of pigs to high-concentration CO2 stunning in a minimal-handling commercial abattoir and the ability to influence stunning efficacy through increased stockperson awareness of optimal animal handling. Behaviour and physiological responses of pigs as they moved from the lairage and through the CO2 stunning system were recorded utilising existing methods, prior to and post a stockperson pig handling training intervention. This study established a baseline for induction of loss of posture that was lower than previously reported for commercial systems, occurring less than 8 s after exposure to CO2, which would indicate loss of consciousness occurring by 23 s after first exposure. The pig handling training intervention was effective in reducing the incidence of high vocalisations and improved the flow of pigs through the raceway and stunner, reinforcing the role of the stockperson in reducing stress pre-slaughter, however, improvements in pigs' response to CO2 within modern stunning systems were not observed. The results from this study indicate that advances in design and operation of CO2 stunning systems have reduced the welfare risk to pigs compared to those reported previously, suggesting further advancements to stunning systems could be made.

Measuring the quality of life of an animal in a production system is difficult, time-consuming, and expensive. We tested the ability of both NIR and MIR spectroscopy, each combined with machine learning, to predict the prior exposure of pigs to long- and short-term life challenges when they are raised in an intensive system. Samples were obtained post-mortem from two locations in the prefrontal cortex. The analysis showed a clear separation between the gray and white matter from the prefrontal cortex with MIR spectroscopy. Exposure to long-term challenge was poorly predicted by the MIR or NIR spectra (< 45% correct classifications). By contrast, the correct classification of samples according to the exposure to a short-tern challenge before death was higher than 65%. These rates of classification, considering the complexity of the stimulus and the small sample size, support that vibrational spectroscopy could be used to assess the exposure to challenging events of an animal on post-mortem brain tissue.

IntroductionEarly life interactions with the sow or humans can have lifelong consequences on welfare and performance in pigs. It was hypothesised that piglets that received increased maternal contact and positive human contact would display improved responses to stressful events and improved performance.MethodsNinety-eight litters were allocated to a 2 x 2 factorial design for maternal contact (MC+)/restricted maternal contact (MC-); and positive human contact (HC+)/no additional human contact (HC-). Modified farrowing crates were used to restrict maternal contact (MC-) and litters in the HC+ treatment received five minutes of daily positive human interaction (stroking). Behavioural and physiological responses were assessed during processing at three days of age and during a behaviour test in which piglets were introduced to an empty arena, novel object, human hand and human standing in the arena at 18 days of age. Observations of behaviour in the home pen and growth and survival of piglets to weaning were also assessed.ResultsAt processing, MC- piglets had more squeals (P = 0.015), tended to have more grunts (P = 0.063) and struggle attempts (P = 0.079), and had increased plasma cortisol concentrations (P = 0.009) after processing than MC+ piglets. During the behaviour test, HC+ piglets were more active (P = 0.014) and had more vocalisations (P < 0.05) in the empty arena than HC piglets. Furthermore, HC+ piglets were more likely to approach a human standing in the arena (P = 0.006) than HC- piglets. MC- piglets were less active (P = 0.008) and were less likely to approach the novel object (P = 0.049) than MC+ piglets. MC+ piglets tended to have higher weaning weights (P = 0.055) and more MC+ piglets were successfully weaned (P = 0.022) than MC- piglets. There was no significant effect of HC on piglet performance.DiscussionWhile positive handling did not affect behavioural and physiological stress response to processing, HC+ reduced fear of novelty and humans. These findings highlight the importance of early life experiences has on stress resilience early in life.

Background Commercial diets are frequently formulated to meet or exceed nutrient levels including those of limiting essential amino acids (AA) covering potential individual variations within the herd. However, the provision of dietary excess of AA, such as Lys, may lead to reduced appetite and growth in pigs. The mechanisms modulating these responses have not been extensively investigated. This study evaluated the effect of Lys dietary excesses on performance and satiety biomarkers in post weaning pigs. Methods Twenty-four pigs aged 21 d and weighing 6.81 ± 0.12 kg (mean ± SEM) were individually housed and offered 1 of 4 dietary treatments for 3 weeks: a diet containing a standardized ileal digestible Lys reaching 100% (T0), 120% (T1), 150% (T2) or 200% (T3) of the NRC (2012) requirements. At the end of the experiment, blood samples from the cephalic vein of the T0 and T3 groups were obtained for AA analysis. In addition, primary intestinal cultures from T0 pigs were used, following their humane killing, to evaluate the effect of Lys on gut hormone secretion and AA sensors gene expression under ex vivo conditions. Results Feed intake was linearly reduced ( P < 0.001) and the weight gain to feed ratio reduced ( P < 0.10) with increased dietary levels of Lys during the third- and first-week post weaning, respectively. Cholecystokinin concentration ( P < 0.05) and the metabotropic glutamate receptor 1 and the solute carrier family 7 member 2 ( P < 0.10) gene expression was enhanced in proximal jejunum tissues incubated with Lys at 20 mmol/L when compared to the control (Lys 0 mmol/L). Plasma Lys and Glu ( P < 0.05) concentration increased in the T3 compared to T0 pigs. In contrast, plasma levels of His, Val, Thr, Leu ( P < 0.05) and Gln ( P < 0.10) were lower in T3 than T0 pigs. Conclusion The present results confirm that excess dietary Lys inhibits hunger in pigs. Moreover, the results provide evidence of pre- and post-absorptive mechanisms modulating these responses. Lys dietary excesses should be narrowed, when possible, to avoid negative effects of the AA on appetite in pigs.

This study investigated the impact of early life interactions on stress resilience of weaner pigs. The hypotheses tested were that reduced maternal contact increases the stress response of pigs to weaning, and that positive human contact during lactation reduces, the stress response of pigs to weaning. Ninety-eight litters were allocated to a 2×2 factorial randomised block design for treatments maternal contact (MC+) / reduced maternal contact (MC-); and positive human contact (HC+) / control (HC-). Modified farrowing crates were used to reduce maternal contact (MC-). Litters in the HC+ treatment received five minutes of daily positive human interaction (stroking). Treatments ceased at weaning (22 days old). Forty-three pigs were mixed into pens of the same treatment at weaning. Behavioral observations were conducted for 2 hours post-weaning and for 4 hours at 2 weeks post-weaning, along with behavioural responses to humans and isolation at 3 and 4 weeks post-weaning, respectively. Cortisol, haptoglobin and IgA concentrations were collected the day prior to weaning at rest, two hours post-weaning, one hour following isolation and at 4 weeks post-weaning and at 5 weeks post-weaning at rest (basal). End weight and survival were also recorded. Results showed that in the first 90 minutes after weaning, HC+ pigs exhibited more inactive behaviours (P<0.05), and less aggressive and eating behaviours (P<0.05) along with more social behaviours (P<0.05) at 90–120 minutes compared to HC- pigs. These findings suggest a quicker stabilisation of behaviour following weaning. While maternal contact did not affect play, aggressive, social or drinking behaviours (P>0.05), MC+ pigs exhibited more eating and active behaviours (P<0.05) from 30 to 60 minutes post-weaning. There were no significant treatment effects (P<0.05) on the physiological measures except at 5 weeks post-weaning where the IgA concentrations of the MC-/HC+ pigs remained steady while those of the other pigs increased five fold (P=0.002). While there were no treatment effects (P<0.05) on the behaviour of pigs at rest at 2-weeks post-weaning, in response to isolation at 4 weeks post-weaning or on performance post-weaning, there was limited evidence that the MC- pigs were less fearful of humans in the test at 3 weeks post-weaning. Based on the behavioural response of pigs immediately following weaning, early positive handling assisted pigs to cope with the stress of weaning. While previous research provided evidence of maternal contact on stress resilience during lactation, the present study provides limited evidence of maternal contact on stress resilience of the weaned pig.

At a time when there is a growing public interest in animal welfare, it is critical to have objective means to assess the way that an animal experiences a situation. Objectivity is critical to ensure appropriate animal welfare outcomes. Existing behavioural, physiological, and neurobiological indicators that are used to assess animal welfare can verify the absence of extremely negative outcomes. But welfare is more than an absence of negative outcomes and an appropriate indicator should reflect the full spectrum of experience of an animal, from negative to positive. In this review, we draw from the knowledge of human biomedical science to propose a list of candidate biological markers (biomarkers) that should reflect the experiential state of non-human animals. The proposed biomarkers can be classified on their main function as endocrine, oxidative stress, non-coding molecular, and thermobiological markers. We also discuss practical challenges that must be addressed before any of these biomarkers can become useful to assess the experience of an animal in real-life.

The ability of pigs to cope with routine farming practices can affect their welfare. This paper is part of a series on early experiences and stress, and reports on the effects of early human contact and housing on the responses of pigs to routine husbandry practices. Using a 2 × 2 factorial design, 48 litters of pigs were raised in either a conventional farrowing crate (FC) or a loose farrowing pen (LP; PigSAFE pen) which was larger, more physically complex and allowed the sow to move freely. Piglets were provided with either routine contact from stockpeople (C), or routine contact plus regular opportunities for positive human contact (+HC) involving 5 min of scratching, patting and stroking imposed to the litter 5 days/week from 0-4 weeks of age. At 4 weeks of age piglets were weaned and re-housed with controlled mixing of litters within treatment. At 4 days of age, after only 3 bouts of the handling treatment, +HC pigs showed less escape behaviour than C pigs after capture by a stockperson for vaccinations and tail docking, and shorter durations of vocalisations throughout the procedures. The +HC pigs also showed less escape behaviour when captured by a stockperson at 3 weeks of age. The FC pigs showed less escape behaviour than LP pigs after capture by a stockperson at 4 days of age but not at 3 weeks of age. Serum cortisol concentrations were lower in FC pigs than LP pigs 2 h after weaning but not at 49 h after weaning, whereas serum cortisol concentrations were lower in +HC pigs than C pigs at 49 h after weaning but not at 2 h after weaning. In the period from 0-1 h after weaning, C pigs from LP performed the most escape attempts, although escape attempts were rare overall. When being moved out of the home pen by a stockperson at 21 weeks of age, FC pigs showed less baulking than LP pigs, but there were no detected effects of human contact treatment. In conclusion, both housing system and human contact during lactation affected the stress responses of pigs to routine husbandry practices. The +HC and FC pigs appeared to cope better than C and LP pigs, based on lower responses indicative of stress including escape behaviour, vocalisations and cortisol concentrations. These findings are consistent with corresponding reductions in fear that were reported in Part 1 of this series of papers.

The development of fear and stress responses in animals can be influenced by early life experiences, including interactions with humans, maternal care, and the physical surroundings. This paper is the first of three reporting on a large experiment examining the effects of the early housing environment and early positive human contact on stress resilience in pigs. This first paper reports on the responses of pigs to humans, novelty, and social isolation. Using a 2 × 2 factorial design, 48 litters of pigs were reared in either a conventional farrowing crate (FC) where the sow was confined or a loose farrowing pen (LP; PigSAFE pen) which was larger, more physically complex and allowed the sow to move freely throughout the farrowing and lactation period. Piglets were provided with either routine contact from stockpeople (C), or routine contact plus regular opportunities for positive human contact (+HC) involving 5 min of scratching, patting and stroking imposed to the litter 5 days/week from 0-4 weeks of age. The positive handling treatment was highly effective in reducing piglets’ fear of humans, based on +HC piglets showing greater approach and less avoidance of an unfamiliar person at 3 weeks of age. There was evidence that this reduction in fear of humans lasted well beyond when the treatment was applied (lactation), with +HC pigs showing greater approach and less avoidance of humans in tests at 6, 9 and 14 weeks of age. The +HC treatment also reduced piglets’ fear of a novel object at 3 weeks of age, and for pigs in FC, the cortisol response after social isolation at 7 weeks of age. Rearing in FC compared to LP reduced piglets’ fear of novelty at 3 weeks of age, as well as their vocalisations and cortisol response to isolation at 7 weeks of age. The FC pigs showed greater approach and less avoidance of humans compared to LP pigs at 3, 4 and 6 weeks of age, but not at 9 and 14 weeks of age. These results show that positive handling early in life can reduce pigs’ fear of humans, fear of novelty and physiological stress response to social isolation. The LP pigs were reared in a more isolated environment with less overall contact with stockpeople and other pigs, which may have increased their fear responses to humans and novel situations, suggesting that different housing systems can modulate these pigs’ responses.

Early experiences can have long-term impacts on stress adaptability. This paper is the last of three in a series on early experiences and stress in pigs, and reports on the effects of early human contact and housing on the ability of pigs to cope with their general environment. Using a 2 × 2 factorial design, 48 litters of pigs were reared in either a farrowing crate (FC) or a loose farrowing pen (LP; PigSAFE pen) which was larger, more physically complex and allowed the sow to move freely. Piglets were provided with either routine contact from stockpeople (C), or routine contact plus regular opportunities for positive human contact (+HC) involving 5 min of scratching, patting and stroking imposed to the litter 5 days/week from 0-4 weeks of age. At 4 weeks of age (pre-weaning), C piglets that were reared in FC had considerably lower concentrations of serum brain-derived neurotrophic factor (BDNF) than piglets from the other treatment combinations. Compared to C pigs, +HC pigs had fewer injuries at 4 weeks of age. There were no clear effects of human contact on BDNF concentrations or injuries after weaning, or on basal cortisol or immunoglobulin-A concentrations, behavioural time budgets, tear staining, growth, or piglet survival. Compared to FC piglets, LP piglets showed more play behaviour and interactions with the dam and less repetitive nosing towards pen mates during lactation. There was no evidence that early housing affected pigs’ behavioural time budgets or physiology after weaning. Tear staining severity was greater in LP piglets at 4 weeks of age, but this may have been associated with the higher growth rates of LP piglets pre-weaning. There was no effect of lactation housing on growth after weaning. Pre-weaning piglet mortality was higher in the loose system. The findings on BDNF concentrations, injuries and play behaviour suggest improved welfare during the treatment period in +HC and LP piglets compared to C and FC piglets, respectively. These results together with those from the other papers in this series, indicate that positive human interactions early in life promotes stress adaptability in pigs. Furthermore, while the farrowing crate environment deprives piglets of opportunities for play behaviour and sow interaction, there was no evidence that rearing in crates negatively affected pig welfare or stress resilience after weaning. Whether these findings are specific to the two housing systems studied here, or can be generalised to other housing designs, warrants further research.

Lay Summary Previous ex vivo studies showed how the amino acids (AA) Lys, Leu, Ile, Phe, and Glu increased satiety peptide cholecystokinin (CCK) and/or insulinotropic hormone glucagon-like peptide 1 (GLP-1) model in pigs. The objective of this study was to validate the ex vivo model by testing the AA of interest in live pigs. Following the oral administration by gavage Leu increased plasma CCK compared to water. Phe showed a sustained long-lasting increase in GLP-1 plasma levels appearing 30 min after the gavage. A positive correlation between CCK and GLP-1 blood levels was observed for Phe treated pigs between 60 and 90 min after the treatment indicating that GLP-1 may induce the release of CCK in the small intestine via feedback mechanisms. The results also showed a trend for Lys increasing CCK congruent with previous data reporting an inhibition of appetite by dietary excess of this AA. These findings are relevant for commercial feeding practices since Lys is often supplemented and dietary Leu is commonly high in pig feeds. Finally, our results highlight the relevance of aromatic AA (i.e., Phe), in pig nutrition that deserves additional attention. There is significant room for improving the understanding of optimal AA levels in pig feeds. Excess dietary amino acids (AA) has been associated with reduced feed intake, increased satiation, and extended satiety in pigs. Recent ex vivo studies suggested that satiety peptide cholecystokinin (CCK) and insulinotropic glucagon-like peptide 1 (GLP-1), mediated the anorexigenic or insulinotropic effects of Lys, Glu, Phe, Ile, and Leu. However, the ex vivo model limitations require validation in vivo. The aim of the present study was to assess the effect of orally administered AA in vivo in pigs. It was hypothesized that oral Lys, Ile, and Leu have an anorexigenic effect via CCK, while Glu and Phe have an insulinotropic effect increasing circulating levels of GLP-1. Eight entire male pigs (Landrace x Large White) of 18.23 +/- 1.06 kg of body weight were administered an oral gavage of water (control) or a 3 mmol/kg of Glu, Ile, Leu, Lys, Phe, or glucose (positive control for GLP-1 release) following an overnight fasting during 5 consecutive days using an incomplete latin square design. Blood samples were collected from the jugular vein before (-5 min, baseline value) and after the gavage (5, 15, 30, 60 and 90 min) to assess CCK and GLP-1 plasma levels. Pigs administered the oral gavage of Leu (P < 0.05), or Lys (P < 0.1) had increased levels of plasma CCK from 0 to 90 min post-gavage when compared to the control. A strong association (P < 0.001) was observed between GLP-1 plasma levels with Phe intake. The impact was significant starting 30 min post-gavage and was sustained until the end of the experiment (90 min post-gavage). Glucose administration increased GLP-1 early after the intake at the 5 min mark (P < 0.1). A positive correlation (P < 0.05, r = 0.89) driven by the impact of Phe at the 60 to 90 min post-gavage was identified between CCK and GLP-1 indicating feedback mechanisms between proximal and distal small intestine. In conclusion, oral gavages of Leu and Lys increased anorexigenic hormone CCK plasma levels in pigs. Phe caused a significant long-lasting increase in incretin GLP-1 plasma levels. Blood CCK and GLP-1 concentrations in Phe gavaged pigs were positively correlated indicating a potential feedback mechanism between proximal (CCK) and distal (GLP-1) small intestine. The present results are compatible with the known anorexigenic effects of excess dietary Leu and Lys, and the insulinotropic effect of Phe in pigs. These results demonstrate the relevance of accurate feed formulation practices particularly in post weaning pigs. The administration of Lys, Leu, Ile, Phe, or Glu by oral gavage resulted in Leu and Lys increasing circulating the satiety hormone CCK, and Phe stimulating the release of the incretin GLP-1. The effect of Phe on GLP-1 was sustained beyond 90 min and triggered a positive correlation with CCK indicating the likely existence of feedback mechanisms between proximal and distal regions of the small intestine. These results are relevant to pig feed formulation practices.

Assessing the health and wellbeing of animals in their natural habitats is a critical yet difficult aspect of species management and conservation. Non- and minimally invasive techniques are increasingly being sought by people working with animals so they can easily monitor the health and wellbeing of the animals without causing them distress. One noninvasive technique that has been in this space is infrared (IR) spectroscopy, which measures the interaction of IR radiation with matter. The ability of IR spectroscopy, especially near-infrared (NIR) and mid infrared (MIR) spectroscopy, to evaluate and monitor animal nutrition, as well as to discriminate physiological attributes of animals (e.g., stress, reproductive status), has been demonstrated by several studies with livestock and wildlife species. However, the use of IR spectroscopy techniques is laden with several challenges, including sample preparation and stability, reliability, and transferability of prediction models. This paper reviews research on the analysis of fecal samples using IR spectroscopy as a proxy in animal health and wellbeing studies. The main challenges of using IR spectroscopy as a portable technology for in-field analysis are also discussed while highlighting key aspects to be considered for in-field applications of NIR and MIR spectroscopy in animal health and wellbeing studies.

Farrowing crates continue to be the most common system of housing farrowing and lactating sows, however continuous confinement is one of the most contentious welfare issues in livestock production. This review aims to critically evaluate the scientific literature on the implications of two important determinants of sow and piglet welfare: housing and human contact. While the evidence in sows is contradictory, there is consistent evidence of a greater short-term cortisol response in gilts introduced to farrowing crates than pens and there is limited evidence of changes in the HPA axis consistent with sustained stress in gilts during the fourth week of lactation. Confinement of sows during lactation increases stereotypic behaviour, reduces sow-piglet interactions, nursing duration and lying behaviour, and may contribute to leg and shoulder injuries in sows. Piglets reared by sows in pens display more play and less oral manipulative behaviours and generally have better growth rates than those reared in farrowing crates. However, there is increasing interest in developing alternate housing systems with minimal sow confinement and reduced piglet mortality risk. Recent research on temporary crating of sows suggests that confinement briefly around farrowing may be the best compromise between continuous housing in farrowing crates and pens, as it may reduce live-born piglet mortality, while providing the opportunity for the sow to move more freely prior to parturition. Together with housing, the behaviour of stockpeople is a key determinant of pig welfare. Recent evidence shows that positive handling of piglets during lactation reduces fear behaviour and physiological stress responses of pigs to humans, novelty and routine husbandry practices, and thus may be enriching for piglets. As a source of enrichment, positive human interactions provide several advantages: close interactions with piglets usually occur several times daily, positive interactions can be combined with routine checks, human interactions invariably provide variability in their predictability which will minimise habituation, and positive interactions may not require additional physical resources. There is a clear need for comprehensive research examining both the short- and long-term welfare implications and the practicality of less confinement of the sow, and positive handling of both sows and piglets during lactation.

The negative effects of seasonality on ram fertility during the spring months (non-breeding season) can be addressed by administration of melatonin. Slow-release implants containing 18 mg of melatonin are available to improve reproductive responses in ewes but as far as we are aware nobody has examined the effects of dose on increasing testicular size and plasma testosterone levels. Mature Border Leicester rams were randomly allocated to four doses (0, 18, 36 and 54 mg) with treatment beginning in mid-September (spring). Measurements (scrotal size, testosterone and melatonin concentrations, live weight and body condition score) began before hormone administration and continued at monthly intervals until January (mid-summer). Scrotal circumference increased with increasing dose with 36 and 54 mg treatments producing larger responses than 0 and 18 mg treatments (p < 0.05). Plasma testosterone concentration was positively related (p <= 0.05) with plasma melatonin levels on days 60 and 90 after melatonin administration. There was a negative relationship (p < 0.01) between plasma melatonin concentration and liveweight on day 30. It is concluded that a higher dose of melatonin is required to maintain plasma melatonin levels in larger animals, and that at least 36 mg is required to elicit a threshold response in testicular size.