Effects of early contact between non-littermate piglets and of the complexity of farrowing conditions on social behaviour and weight gain

Early human contact and housing for pigs - part 2: resilience to routine husbandry practices

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 to 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 to 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.

Review: Early life piglet experiences and impacts on immediate and longer-term adaptability

Pigs in production systems are routinely exposed to challenging situations including abrupt weaning, painful husbandry procedures, intense contact with stockpeople, and exposure to novel social and physical environments. The resilience of pigs to these stressors has implications for animal welfare and productivity and can be affected by early life experiences. In rodents and primates, early experiences with stressors that the animal can adequately cope with confers future stress adaptability, leading to less abnormal behaviour, lower behavioural and physiological responses to stressors, and faster recovery after stress exposure. Early experiences that can affect the ability of pigs to overcome challenge include interactions with the dam, conspecifics, humans, and the overall complexity of the environment. Farrowing crates limit the sow's ability to show maternal behaviour towards piglets, and negatively affect piglet social behaviour during lactation, with less play and more manipulation of pen mates in crates than in large pens. Rearing in pens has been proposed to improve the ability of pigs to cope with routine stressors, but the evidence for this is conflicting. The early housing environment can affect general fearfulness and fear of humans, and surprisingly, most studies have shown fear responses to be greater in pigs reared pens than in crates. Given the potential for fear to affect animal welfare and productivity, more detailed research on early housing effects is needed. While there is limited evidence that early housing influences fear in the longer term, human contact early in life appears to have a more profound and sustained effect, with regular positive human interaction early in life having an enduring effect on reducing pigs' fear of humans. The practicality of positive human-pig interaction in a commercial environment needs to be examined further, but only a small amount of positive human contact early in life can improve the resilience of pigs to routine husbandry stressors. Early social experience with non-littermates reduces stress at weaning and mixing, while early weaning before 3-4 weeks of age increases abnormal behaviours. Environmental enrichment, such as foraging substrates and increased floor space, reduces abnormal behaviour in piglets, but housing in an enriched environment early in life and subsequently in a non-enriched environment can increase abnormal behaviour if these environments are dramatically different. Although the later environment can modify the influence of the early environment, overall, early life experiences can be important in shaping how pigs cope with stress in both an immediate and longer-term capacity.

Burlap and buddies: the effects of social enrichment (preweaning mixing) and object enrichment (burlap) on piglet performance, behavior, and welfare in the preweaning environment

When weaned in commercial operations, piglets are not only separated from their sow but also mixed with unfamiliar pigs in an unfamiliar environment with a new diet. These abrupt changes can be stressful for piglets, often having negative welfare consequences. Our objective was to study the effects of early-life preweaning socialization and object enrichment in the preweaning environment. We compared piglet performance, behavior, and welfare across six treatments that combined multi-litter group size (1 vs. 2 vs. 4 litters) and burlap (yes vs. no). We recorded piglet behavior and lesion-scored sows and piglets. Normal conforming data, expressed per experimental unit (and behavior data were averaged over time), were analyzed by ANOVA. When given the opportunity in the sow barn, piglets in multi-litter groups socialized with other litters. Burlap use (P = 0.08) was observed in < 5% of the observations but tended to increase in mixed litter groups. Cross-sucking was observed in ~12% of the observations within mixed litter groups and tended to increase with mixed group size (P = 0.08). While there was no difference in the proportion of piglets nursing (P > 0.10), piglets were less active in the single crate groups and most active in the groups of two litters mixed (P = 0.03). Additionally, observed piglet/sow biting behaviors did not differ between treatments; however, piglet-piglet biting (P = 0.07), and pen object manipulation (P = 0.07) tended to be observed more frequently in non-enriched groups. Piglet displacements were observed more often in non-enriched groups around the pen (P = 0.03) but tended to be observed more often in enriched groups at the teat (P = 0.07). Preweaning socialization and object enrichment had no impact on the average number of piglets weaned per sow or total piglet mortality (P > 0.10). However, the proportion of laid-on piglets decreased as the number of mixed litters increased (P = 0.02). The average number of lesions per piglet did not differ between treatments. Although the final lesion scores of sow teat and udder condition did not differ between treatments (P > 0.10), sow udder scores tended to worsen more in the single litters than in the mixed litters (P = 0.08). Overall, social and object enrichment allows piglets to socialize at a younger age and to redirect their attention toward an object (burlap) which does not negatively impact piglet or sow performance, or behavior, and may improve piglet welfare around weaning.

Burlap and buddies: the effects of social enrichment (preweaning mixing) and object enrichment (burlap) on piglet behavior and welfare in the postweaning environment

The process of weaning piglets in commercial swine operations subjects them to numerous abrupt and stressful changes often resulting in negative welfare consequences. The objective was to study the postweaning effects of early-life (1 to 3 d of age) preweaning socialization in multi-litter groups as well as object enrichment (burlap sheet) in the pre- and postweaning environment by comparing six treatments that combined mixing of one vs. two vs. four litters mixed preweaning with and without burlap provision. An ANOVA linear model was run on all normal data, expressed per experimental unit (and behavior data were averaged over time), while non-normal data were analyzed using the Kruskal-Wallis test. Non-enriched groups of piglets were observed manipulating pen objects more often than the enriched groups (P = 0.005). Biting behaviors, including the chewing of ears and tails of pen-mates but excluding fighting, were observed the least in groups of pigs of four litters mixed preweaning, while piglets that were not mixed preweaning were observed biting the most (P = 0.03). Piglets who were not mixed preweaning also manipulated the burlap more frequently than the piglets from groups of 4 litters mixed preweaning (P = 0.02). Biting (P < 0.001) and displacements (P = 0.03) and fighting (P = 0.002) throughout the pen were observed less in the enriched groups. There were fewer lesions per pig in the enriched groups vs. non-enriched groups initially (P = 0.07) and 1 wk after weaning (P = 0.10). Furthermore, pigs mixed in groups of four litters preweaning also tended to have lower lesion scores (P = 0.07) 1-wk postweaning compared to the other treatments. However, there were no differences between treatments in the proportion of piglets resting, eating/drinking, being active, or using the burlap, or for the observed frequency of displacements at the feeder, social behaviors, or belly nosing (P > 0.10). Overall, social enrichment encourages socialization with unfamiliar conspecifics at a younger age while object enrichment allows pigs to redirect their attention toward objects such as burlap. Both may improve pig behavior and welfare after weaning.

Reducing Weaning Stress in Piglets by Pre-Weaning Socialization and Gradual Separation from the Sow: A Review

The weaning of pigs in most commercial pork production systems is an abrupt event performed at a fairly young age, i.e., mostly between 2.5 and 5 weeks of age. This practice induces a stress response, and its impact on behavior, performance and the gastrointestinal tract has been well described. Historically, there has been a focus on pre- and post-weaning nutritional strategies and post-weaning housing conditions and medication to improve production and reduce mortality after weaning. However, alternative pre-weaning housing and management systems that promote the development of natural social behaviors of piglets before weaning have recently received more attention. Co-mingling of non-littermates before weaning is a strategy that aims to initiate social interactions prior to weaning. The separation of the litter from the sow in the period leading up to weaning, termed intermittent suckling, aims to enhance the gradual separation from the sow. In addition, these practices encourage the young pig to learn explorative nutrient sourcing. Altogether, they may reduce weaning-associated stress. In this review, these strategies are defined, and their effects on behavior, performance, mortality, gastrointestinal function and immunocompetence are described. Though these strategies may be adapted to a commercial setting, it also becomes clear that many factors can contribute to the success of these strategies.

Socializing Models During Lactation Alter Colonic Mucosal Gene Expression and Fecal Microbiota of Growing Piglets

The enrichment of the social environment during lactation alleviates the stress of weaned piglets. It is significant to understand how the enriched social environment improves the weaning stress of piglets. RNA sequencing (RNA-seq) of colonic mucosa, 16S rRNA sequencing of feces, and short-chain fatty acids (SCFAs) of colonic content were used to determine the effects of social contact during lactation. In this study, thirty litter lactating piglets were divided into intermittent social contact (ISC) group that contacted with neighbors intermittently, continuous social contact (CSC) group that contacted with neighbors starting at day (D) 14 after birth, and control (CON) group in which piglets were kept in their original litter. The piglets were weaned at D35 and regrouped at D36. The colonic mucosal RNA-seq, fecal microbes, and SCFAs of colonic contents of 63-day-old piglets were analyzed. The results of RNA-seq showed that compared with the CON group, the pathways of digestion and absorption of minerals, protein, and vitamins of piglets were changed in the ISC group, whereas the pathways of retinol metabolism and nitrogen metabolism in the colonic mucosal were affected and stimulated the immune response in the CSC group. Compared with the CON group, the abundances of pernicious microorganisms (Desulfovibrio, Pseudomonas, Brevundimonas, etc.) in the CSC group and pernicious microorganisms (Desulfovibrio, Neisseria, Sutterella, etc.) and beneficial bacteria (Bifidobacterium, Megamonas, and Prevotella_9) in the ISC group were significantly higher (p < 0.05). The abundances of proinflammatory bacteria (Coriobacteriaceae_unclassified, Coprococcus_3, and Ruminococcus_2) in the CSC group were significantly increased (p < 0.05), but the abundances of SCFAs producing bacteria (Lachnospiraceae_UCG-010, Parabacteroides, Anaerotruncus, etc.) and those of anti-inflammatory bacteria (Eubacterium, Parabacteroides, Ruminiclostridium_9, and Alloprevotella) were significantly reduced (p < 0.05) in the CSC group. Compared with the CON group, the concentrations of microbial metabolites, acetate, and propionate in the colonic contents were reduced (p < 0.05) in the ISC group, whereas the concentration of acetate was reduced (p < 0.05) in the CSC group. Therefore, both ISC and CSC during lactation affected the composition of fecal microbes and changed the expression of intestinal mucosal genes related to nutrient metabolism and absorption of piglets.

Systematic review of animal-based indicators to measure thermal, social, and immune-related stress in pigs

The intense nature of pig production has increased the animals’ exposure to stressful conditions, which may be detrimental to their welfare and productivity. Some of the most common sources of stress in pigs are extreme thermal conditions (thermal stress), density and mixing during housing (social stress), or exposure to pathogens and other microorganisms that may challenge their immune system (immune-related stress). The stress response can be monitored based on the animals’ coping mechanisms, as a result of specific environmental, social, and health conditions. These animal-based indicators may support decision making to maintain animal welfare and productivity. The present study aimed to systematically review animal-based indicators of social, thermal, and immune-related stresses in farmed pigs, and the methods used to monitor them. Peer-reviewed scientific literature related to pig production was collected using three online search engines: ScienceDirect, Scopus, and PubMed. The manuscripts selected were grouped based on the indicators measured during the study. According to our results, body temperature measured with a rectal thermometer was the most commonly utilized method for the evaluation of thermal stress in pigs (87.62%), as described in 144 studies. Of the 197 studies that evaluated social stress, aggressive behavior was the most frequently-used indicator (81.81%). Of the 535 publications examined regarding immune-related stress, cytokine concentration in blood samples was the most widely used indicator (80.1%). Information about the methods used to measure animal-based indicators is discussed in terms of validity, reliability, and feasibility. Additionally, the introduction and wide spreading of alternative, less invasive methods with which to measure animal-based indicators, such as cortisol in saliva, skin temperature and respiratory rate via infrared thermography, and various animal welfare threats via vocalization analysis are highlighted. The information reviewed was used to discuss the feasible and most reliable methods with which to monitor the impact of relevant stressors commonly presented by intense production systems on the welfare of farmed pigs.

A multi-suckling system combined with an enriched housing environment during the growing period promotes resilience to various challenges in pigs

Little is known about the impact of social and environmental enrichment on improving livestock resilience, i.e. the ability to quickly recover from perturbations. We evaluated the effect of an alternative housing system (AHS) on resilience of pigs, as compared to conventional housing (CONV). The AHS consisted of multi-litter housing during lactation, delayed weaning, extra space allowance and environmental enrichment at all times. We assessed recovery to a 2 h-transport challenge, an LPS injection, 2 h-heat stress and a biopsy wound in 96 pigs. Additionally, indicators of long-term “wear and tear” on the body were determined. AHS pigs had better physiological recoveries with quicker returns to baseline in the transport and LPS challenges, showed lower cortisol accumulation in hairs and lower variance in weight gain over the experimental period compared to conventionally-housed (CONV) pigs. They also had higher levels of natural antibodies binding KLH than CONV pigs. Their response to heat stress revealed a different strategy compared to CONV pigs. Taken together, AHS pigs appear to be more resilient and experience less chronic stress. Enhancing welfare by provision of social and environmental enrichment that better meets the behavioural needs of pigs seems to be a promising approach to improve their resilience.

Early socialisation in group lactation system reduces post-weaning aggression in piglets

BACKGROUND

Pre-weaning group housing for sows and their litters is expected to enhance animal welfare. However, knowledge of potential benefits of pre-weaning socialisation for piglets after weaning is still lacking.

METHODS

Weaner pigs were mixed in groups of 10, using littermates (LM) from pre-weaning group housing (Gr) and from farrowing pens with crates (Co). Groups were formed as follows: Gr/Gr (5 LM from Gr + 5 LM from Gr), Gr/Co (5 LM from Gr + 5 LM from Co), Co/Co (5 LM from Co + 5 LM from Co).

RESULTS

During 24 h after mixing, piglets in Co/Co fought more than in Gr/Co and Gr/Gr. Piglets in Co/Co had more unclear fighting results than in Gr/Co and Gr/Gr. Four days after mixing, piglets in Co/Co were more injured than in Gr/Co and Gr/Gr.

CONCLUSION

Early socialised piglets may have better social skills when meeting familiar and unfamiliar conspecifics after weaning.

Effects of Different Housing Systems during Suckling and Rearing Period on Skin and Tail Lesions, Tail Losses and Performance of Growing and Finishing Pigs

Feasible alternatives to stressful weaning and tail-docking are needed to inhibit tail biting. Therefore, we investigated the effects of housing systems for 1106 pigs that were weaned from: (1) conventional farrowing crates (FC), (2) free-farrowing pens (FF), or (3) group housing of lactating sows (GH) into (1) conventional rearing pens (Conv) or (2) piglets remained in their farrowing pens for rearing (Reaf). Tails were docked or left undocked batchwise. All pigs were regrouped for the fattening period. Pigs were scored for skin lesions, tail lesions and losses. After weaning, Conv-GH pigs had significantly less skin lesions than Conv-FC and Conv-FF pigs. After regrouping for fattening, Reaf-GH pigs had significantly less skin lesions than Conv pigs, Reaf-FC and Reaf-FF. The frequency of tail lesions of undocked Conv pigs peaked in week 4 (66.8%). Two weeks later, Reaf undocked pigs reached their maximum (36.2%). At the end of fattening, 99.3% of undocked Conv pigs and 43.1% of undocked Reaf pigs lost parts of their tail. In conclusion, the co-mingling of piglets during suckling reduced the incidence of skin lesions. Rearing in the farrowing pen significantly reduced the incidence of tail lesions and losses for undocked pigs. No housing system negatively affected the performance.

Positive Human Contact and Housing Systems Impact the Responses of Piglets to Various Stressors

Simple Summary

Early life experiences such as contact with humans, maternal care and the physical environment can play a substantial role in shaping behavioural and physiological responses to stress. This experiment studied the effects of lactation housing systems and human interaction on stress in young pigs. We hypothesised that piglets handled in a positive manner and reared in loose farrowing and lactation pens with increased opportunity for interaction with their dam, greater space and more complexity in their physical environment have improved stress resilience than piglets reared in traditional farrowing crates with routine contact from stockpeople. In both housing systems, providing regular opportunities for positive human interaction reduced piglets’ fear of humans and routine husbandry procedures imposed by humans, and reduced the number of injuries obtained after weaning. However, contrary to the expected findings, piglets from loose farrowing and lactation pens were more reactive to capture by a stockperson, more fearful of novel and human stimuli, had more injuries during the lactation period and were more likely to perform behaviours which may be indicative of reduced coping after weaning. Whether these effects are specific to the loose farrowing and lactation system studied in this experiment or are reflective of other loose systems requires further research.

Abstract

This experiment studied the effects of lactation housing systems and human interaction on piglets’ responses to routine stressors. Forty litters of piglets were reared in either a standard farrowing crate (FC) or a loose farrowing and lactation pen (LP; PigSAFE pen) and received either routine contact with humans (C) or regular opportunities for positive human contact (+HC; 3 min of patting, stroking and scratching 5 times/week). Behavioural and physiological responses to routine husbandry procedures, weaning, novelty and humans were studied in addition to effects on piglet growth, injuries and survival. Compared to C piglets, +HC piglets vocalised for shorter durations (p = 0.018) during husbandry procedures and showed a lower intensity of escape behaviour during iron injection (p = 0.042) and oral vaccination (p = 0.026) at 3 d of age, capture at 2 wk of age (p < 0.001), and intramuscular vaccination (p = 0.005) at 3 wk of age. +HC piglets at 2 wk of age were faster than C piglets to approach (p = 0.048) and interact (p = 0.042) with a stationary unfamiliar human. Compared to LP piglets, FC piglets showed a lower intensity of escape behaviour during capture and iron administration by a stockperson at 3 d of age (p = 0.043). FC piglets at 2 wk of age were faster than LP piglets to approach (p = 0.005) and interact (p = 0.027) with a novel object and approach (p = 0.009) and interact (p = 0.008) with an unfamiliar human. FC piglets had fewer injuries than LP piglets at 2 wk of age (p = 0.004). +HC pigs had fewer injuries than C pigs after weaning (p = 0.003). After weaning there were more pigs from LP than FC observed to be upright (both stationary, p = 0.002 and walking, p = 0.024), vocalizing (p = 0.004), nosing another pig (p = 0.035) and nosing the pen floor (p = 0.038). There were no significant effects on neutrophil:lymphocyte ratios or plasma cortisol concentrations 1.5 h after weaning. However, 25 h after weaning +HC pigs had higher haptoglobin concentrations than C pigs (p = 0.002), and C/LP pigs had higher cortisol concentrations than +HC/LP and C/FC pigs (p = 0.012). There were no significant effects on piglet growth, the number of piglets born alive or the number stillborn, however there were more piglets weaned from FC than LP (p = 0.035). The results from this experiment raise questions that require further research on the ability of pigs reared in loose pens to cope with stressors such as exposure to humans, novelty, husbandry procedures and weaning. This experiment also provides evidence that regular positive human interaction reduces pigs’ fear of humans and husbandry procedures imposed by stockpeople. More research is required to determine if any of these effects are sustained long-term.

An estimation of the financial consequences of reducing pig aggression

Animal welfare scientists have accumulated knowledge and developed interventions to improve livestock welfare, but these are poorly adopted in commercial practice. Animal welfare interventions are rarely tested for economic viability and this limits their uptake. This study employs Stochastic Partial Budgeting (SPB) to determine the viability of animal welfare improvements. Aggression between pigs is used as an example because there is a large literature base from which to draw interventions, and the problem has persisted for decades without resolution. Costs and benefits of three interventions to control aggression (pre-weaning socialisation, synthetic maternal pheromones and large social groups) were estimated by reviewing the academic and industry literature and by conducting a survey of sixteen pig farmers. The net effects were compared to farmers’ willingness to pay (WTP) for interventions to reduce aggression as identified by recent research. Results are consistent with prior research which indicates that improving animal welfare generally comes at a cost to producers. Nevertheless, pre-weaning socialisation resulted in a neutral or positive net effect 38% of the time and should be central to campaigns promoting the control of aggression in the industry. Exposing pigs to synthetic maternal pheromones did not improve profitability but the net costs were small and within the realms of WTP for a sub-group of farmers with animal welfare goals. The net costs of converting existing buildings in order to house pigs in large social groups were beyond the realms of farmers’ WTP. The approach adopted in this study, of combining SPB with WTP from the sector, should be extended to other animal welfare issues.

Management and Feeding Strategies in Early Life to Increase Piglet Performance and Welfare around Weaning: A Review

The performance of piglets in nurseries may vary depending on body weight, age at weaning, management, and pathogenic load in the pig facilities. The early events in a pig's life are very important and may have long lasting consequences, since growth lag involves a significant cost to the system due to reduced market weights and increased barn occupancy. The present review evidences that there are several strategies that can be used to improve the performance and welfare of pigs at weaning. A complex set of early management and dietary strategies have been explored in sows and suckling piglets for achieving optimum and efficient growth of piglets after weaning. The management strategies studied to improve development and animal welfare include: (1) improving sow housing during gestation, (2) reducing pain during farrowing, (3) facilitating an early and sufficient colostrum intake, (4) promoting an early social interaction between litters, and (5) providing complementary feed during lactation. Dietary strategies for sows and suckling piglets aim to: (1) enhance fetal growth (arginine, folate, betaine, vitamin B12, carnitine, chromium, and zinc), (2) increase colostrum and milk production (DL-methionine, DL-2-hydroxy-4-methylthiobutanoic acid, arginine, L-carnitine, tryptophan, valine, vitamin E, and phytogenic actives), (3) modulate sows' oxidative and inflammation status (polyunsaturated fatty acids, vitamin E, selenium, phytogenic actives, and spray dried plasma), (4) allow early microbial colonization (probiotics), or (5) supply conditionally essential nutrients (nucleotides, glutamate, glutamine, threonine, and tryptophan).

The influence of early life socialisation on cognition in the domestic pig (Sus scrofa domestica)

Previously, the benefits of early-life socialisation on later-life social development have been reported in pigs. Here we investigated the effect of pre-weaning socialisation on the later-life cognitive ability of pigs using a range of techniques. Pre-weaning, 101 piglets had access to a neighbouring pen from ~ 15 days of age and interacted with non-littermates (socialised). An additional 89 piglets remained isolated within their home pen (controls). After weaning, 100 individuals were selected for a range of cognitive tests including a food reward T-maze test, reversal learning T-maze test, a social preference T-maze test, and a puzzle box test. Performance during the food reward test was not influenced by treatment. Treatment effected improvement over the course of the reversal learning test, with controls showing a significant decrease in trial duration after the first two trials. During the social preference test, socialised pigs spent significantly more time in the presence of larger stimulus pigs than controls and were quicker to leave the middle of the maze, suggesting improved social skills. Neither sex nor treatment was observed to influence pig's ability to solve the puzzle box. Thus, overall, evidence from the social preference test suggests an effect of pre-weaning socialisation on aspects of social cognitive development.

Sow behaviour and piglet weight gain after late cross-fostering in farrowing crates and pens

Determining best practices for managing free farrowing systems is crucial for uptake. Cross-fostering, the exchange of piglets between litters, is routinely performed amongst crate-housed sows. However, cross-fostering can increase fighting amongst the litter and may be more challenging within free farrowing systems as sows have more freedom to respond to cross-fostered piglets. This study compared the effect of either cross-fostering (FOS), or a control of sham-fostering (CON), of four focal piglets per litter on Day 6 postpartum in crates (CRATE) and free farrowing pens (PEN). The post-treatment behavioural responses of sows were recorded (Day 6 = 60 min; Day 7 = 300 min; n = 48), as were the average daily gain (ADG; g/day), total weight gain (TWG; kg) and body lesion scores of focal piglets and their littermates throughout lactation (Day 6, Day 8, Day 11 and Day 26; n = 539) and the post-weaning period (Day 29, Day 32 and Day 60; n = 108). On Day 6, though post-reunion latency to nursing did not differ, latency to successful nursing was longer amongst FOS than CON litters (P < 0.001), more so amongst CRATE FOS than PEN FOS (P < 0.01). On Day 7, PEN FOS sows had fewer successful nursing bouts (P < 0.05) and exhibited decreased lateral (P < 0.01) and increased ventral lying frequencies (P < 0.01) compared to all other housing and treatment combinations. Focal piglet ADG was lower for FOS than CON in the CRATE during Day 6 to Day 8 (P < 0.01) and lower in the PEN during Day 6 to Day 8 (P < 0.001), Day 8 to Day 11 (P < 0.01) and Day 11 to Day 26 (P < 0.05). The TWG of pre-weaned focal piglets (Day 6 to Day 26) was higher amongst CON than FOS litters (P = 0.01). Post-weaning, piglet ADG was higher for PEN than CRATE during Day 26 to Day 29 (P < 0.01) and higher for FOS than CON during Day 26 to Day 29 (P < 0.05), Day 29 to Day 32 (P < 0.001) and Day 32 to Day 60 (P < 0.01); thus, TWG was higher for FOS than CON during the weaner (P = 0.001) and the combined lactation and weaner periods (P = 0.09). In conclusion, sow behaviour was disrupted by cross-fostering in the crates and pens and continued to be disturbed on the following day amongst penned sows. FOS piglets exhibited reduced ADG after cross-fostering, which extended throughout lactation in the pens. However, the increased post-weaning weight gain of FOS piglets meant that their TWG was higher than CON piglets, irrespective of the farrowing system used.

Review: Early life predisposing factors for biting in pigs

The pig industry faces many animal welfare issues. Among these, biting behaviour has a high incidence. It is indicative of an existing problem in biters and is a source of physical damage and psychological stress for the victims. We categorize this behaviour into aggressive and non-aggressive biting, the latter often being directed towards the tail. This review focusses specifically on predisposing factors in early life, comprising the prenatal and postnatal periods up to weaning, for the expression of aggressive and non-aggressive biting later in life. The influence of personality and coping style has been examined in a few studies. It varies according to these studies and, thus, further evaluation is needed. Regarding the effect of environmental factors, the number of scientific papers is low (less than five papers for most factors). No clear influence of prenatal factors has been identified to date. Aggressive biting is reduced by undernutrition, cross-fostering and socialization before weaning. Non-aggressive biting is increased by undernutrition, social stress due to competition and cross-fostering. These latter three factors are highly dependent on litter size at birth. The use of familiar odours may contribute to reducing biting when pigs are moved from one environment to another by alleviating the level of stress associated with novelty. Even though the current environment in which pigs are expressing biting behaviours is of major importance, the pre-weaning environment should be optimized to reduce the likelihood of this problem.

The welfare and productivity of sows and piglets in group lactation from 7, 10, or 14 d postpartum

Transferring sows and their litters to group lactation (GL) after an initial period of farrowing crate (FC) housing could enhance the viability of GL for commercial production. Group lactation from 7 d postpartum would reduce the time sows spend in confinement, but the effects of early mixing on animal welfare and productivity require examination. Two experiments were conducted on sows and piglets kept in GL from 7, 10, or 14 d postpartum, compared with FC. Experiment 1 utilized 180 sows and 1,887 piglets over five time replicates (n = 60 sow and litter units per treatment) comparing GL from 7 or 14 d postpartum to FC. In experiment 2, 108 sows and 1,179 piglets were studied over three time replicates (n = 36 sow and litter units per treatment) comparing GL from 10 or 14 d postpartum to FC. All sows farrowed in FC. Group lactation sows were transferred to pens (one pen of five sows at 8.4 m2/sow and one pen of seven sows at 8.1 m2/sow, per GL treatment and replicate) with their litters at 7 (GL7), 10 (GL10), or 14 (GL14) d postpartum. Farrowing crate sows and their litters remained in their FC. Data were collected on sow feed intake and reproduction, piglet mortality (from day 6 postpartum), and sow and piglet weight changes, plasma cortisol concentrations, and injuries. Piglet mortality was greater in the GL7 (17 ± 1.8%) and GL10 treatments (12 ± 0.9%) compared with GL14 (8.3 ± 1.8% P ≤ 0.001 and 8.1 ± 0.9% P ≤ 0.001 in experiments 1 and 2), and greater in GL overall compared with FC (2.7 ± 1.5% and 1.8 ± 0.9% in FC in experiments 1 and 2; P ≤ 0.001). Piglets from GL7 were also lighter at weaning than GL14 piglets (P < 0.001), whereas GL10 and GL14 did not differ (P > 0.05). Overall, piglets in GL were lighter at weaning than piglets in FC (P ≤ 0.01). Sows from GL7 were heavier at weaning (P = 0.001), and GL10 sows tended to be heavier at weaning (P = 0.08), than GL14 and FC sows. Post-mixing, sow cortisol (P ≤ 0.01) and sow and piglet injuries (P ≤ 0.02) were greater in GL than FC. Treatment had no effect on sow feed intake or reproductive performance (P > 0.05). Under the conditions of this research, the known benefits of two-stage GL housing were achieved at a cost particularly to piglets in terms of increased piglet mortality and injuries after mixing, and reduced piglet growth. The risk of piglet mortality decreased with older age at mixing.

Mixing Sows into Alternative Lactation Housing Affects Sow Aggression at Mixing, Future Reproduction and Piglet Injury, with Marked Differences between Multisuckle and Sow Separation Systems

Simple Summary

Alternative lactation housing could reduce aggression when sows are mixed. We aimed to compare the effects of mixing sows during lactation (with or without piglets) at weaning and after insemination and determine the effects of mixing strategies and lactation housing on the piglet. Sows in the multisuckle treatment were the least aggressive, had the fewest injuries around mixing, and gave birth to the most piglets at the subsequent litter, with multisuckle housing having no apparent ill effects on the piglets. There was greater aggression in sows separated from their piglets for seven hours daily in lactation (SEP) than any other method. Multisuckle housing appears to be an effective way of decreasing aggression at the point of mixing, whilst optimizing sow reproduction. The behavioural response to mixing was similar when it occurred at weaning or after insemination, with the highest incidence of aggression observed in sows mixed without their piglets during lactation.

Abstract

Alternative lactation housing could reduce aggression when sows are mixed. We aimed to compare the effects of mixing sows in lactation (with or without piglets), at weaning or after insemination, and determine the effects of lactation housing on the piglet. This study used 120 multiparous Large White × Landrace sows and 54 focal litters. The sows were mixed into groups of six and allocated to multisuckle from day 21 lactation (MS), separated from litter and housed in groups, with piglets left in the crate for seven hours daily from day 21 lactation (SEP), mixed at weaning (day 28 lactation) (WEAN) and mixed after artificial insemination (AI) (MAI; 4 ± 1 day after last AI). Behaviour, saliva for free salivary cortisol concentration and injury counts were taken on M-1 (before mixing), M0 (mixing), M1 and M6. Piglets were weighed, injury-scored and bloods taken for cortisol. There was reduced aggression, seen as fights, bites and knocks in MS compared to the other treatments on all days (p < 0.05). MS sows had no fights on M1 and M6 and had more piglets born in the subsequent farrowing. Piglet weight, cortisol and mortality were unaffected by treatment (p > 0.05). MS piglets had greater injury scores immediately after moving to multisuckle and lower injuries around weaning (p > 0.001). Multisuckle housing could decrease aggression and stress at mixing in sows, with changes in the time of peak piglet injury (at mixing rather than at weaning) but overall no negative effects on the piglets.

Group lactation from 7 or 14 days of age reduces piglet aggression at weaning compared to farrowing crate housing

Early life experiences can affect social behaviour in later life, but opportunities for socio-behavioural development are often overlooked in current husbandry practices. This experiment investigated the effects of rearing piglets in two-stage group lactation (GL) system from 7 or 14 days of age on piglet aggression at weaning. Three lactation housing treatments were applied to a total of 198 piglets from 30 litters of multiparous sows. All dams farrowed in standard farrowing crates (FCs). Group lactation litters were transferred with their dam at 7 (GL7) or 14 days (GL14) postpartum to GL pens (one pen of five sows at 8.4 m2/sow and one pen of seven sows at 8.1 m2/sow, per GL treatment). Farrowing crate litters remained with their dam in a single litter until weaning. At weaning, 10 to 14 piglets from two unfamiliar litters from the same housing treatment were mixed into pens (n=5 pens/treatment) and their behaviour was continuously recorded for 3.5 h. For each pen, the frequency of aggressive bouts (reciprocal and non-reciprocal aggression lasting <5 s), the frequency and duration of fights (reciprocal aggression lasting ⩾5 s) and bullying events (non-reciprocal aggression lasting ⩾5 s) were recorded, along with whether interactions involved familiar or unfamiliar piglets. Aggressive bouts delivered by FC piglets were approximately 1.5 and 3.0 times more frequent than that delivered by GL7 and GL14 piglets, respectively (40.5, 16.7 and 9.9 bouts/pig, respectively; P<0.05). Fighting was more frequent (1.6, 0.3 and 0.4 fights/pig, respectively; P<0.001) and fights were longer (83, 15 and 32 s fight/pig, respectively; P<0.001) between FC piglets than between GL7 or GL14 piglets. Bullying did not differ between housing treatments (P>0.05). GL7 and GL14 piglets engaged in a similar number of fights with unfamiliar as familiar piglets, but FC piglets had almost three times as many fights with unfamiliar than with familiar piglets (P<0.05). This experiment confirms the benefits of GL housing for pig social development. Further investigation is required to determine whether mixing before 14 days postpartum has implications for other indicators of animal welfare and productivity in a two-stage GL housing system.

Socialisation and its effect on play behaviour and aggression in the domestic pig (Sus scrofa)

There is considerable interest in how early life experiences shape behavioural development. For example, the socialisation of unfamiliar pigs pre-weaning has been suggested to decrease aggression during later life. However, the behavioural mechanisms behind this socialisation effect remain unexplored. We allowed 12 litters of domestic pigs (Sus scrofa) to move freely between their home pen and a neighbouring pen (socialisation) during the lactation period, while keeping 12 litters isolated in their home pen (control). Contrary to predictions, socialisation did not result in higher levels of social play. However, control individuals engaged in more sow directed play than those that underwent socialisation. Consistent with predictions, males performed more piglet directed play than females. Social play behaviour pre-weaning was found to be highly concordant within individuals from both treatments. Post-weaning, 148 pigs were selected to perform two resident-intruder tests to assay aggressiveness. As predicted, socialised individuals were quicker to attack than controls, although females were more aggressive than males. Additionally, play fighting experience was found to negatively correlate with attack latency in females, supporting the hypothesis that early-life play experience is likely to be sexually dimorphic when males and females show pronounced differences in their later-life social behaviour.

Gastrointestinal tract (gut) health in the young pig

An optimally functioning gastrointestinal tract (GIT) clearly is of importance to the overall metabolism, physiology, disease status and performance of pigs of all stages of growth and development. Recently, the 'health' of the GIT ('gut health') has attracted much attention despite the lack of a clear definition to the term or its aetiology, although in broad terms, 'gut health' encompasses a number of physiological and functional features including nutrient digestion and absorption, host metabolism and energy generation, a stable and appropriate microbiota/microbiome, defence mechanisms including barrier function and mucosal immune mechanisms, and the interactions between these components. 'Gut health' in the newly-weaned (young) pig is of obvious interest due to changes in GIT structure and function associated with the post-weaning transition, and more recently to the upsurge in interest in different feed additives as dietary alternatives/replacements caused by bans/reductions in certain antimicrobial compounds being available in some parts of the world. In the presence of enteric disease(s) after weaning, a deterioration in 'gut health' may be synonymous to the overall health of the pig, and although some direct relationships can be drawn between pig performance and efficiency and a 'healthy' GIT, sometimes this connection is subtler and less obvious, especially in the absence of overt enteric disease(s). The factors and conditions involved in 'gut health' are multifactorial, complex, often poorly described and sometimes incorrectly interpreted, although it is evident that perturbations of the GIT can cause an imbalance and disturb the generalized homeostasis. In addition to any enteric diseases or conditions that might arise as a result of these disturbances, other influences will also impact such as the responses occurring in the GIT in the period immediately after weaning, any changes that might occur after a change in diet, and (or) disruptions to meal patterns and hence the flow of nutrients. Ultimately, 'gut health' represents the outcome of the GIT in response to its capacity and ability to respond and adapt to the insults and challenges it encounters.

Post-weaning social and cognitive performance of piglets raised pre-weaning either in a complex multi-suckling group housing system or in a conventional system with a crated sow

We studied the social and cognitive performance of piglets raised pre-weaning either in a conventional system with a sow in a farrowing crate (FC) or in a multi-suckling (MS) system in which 5 sows and their piglets could interact in a more physically enriched and spacious environment. After weaning at 4 weeks of age, 8 groups of 4 litter-mates per pre-weaning housing treatment were studied under equal and enriched post-weaning housing conditions. From each pen, one pair consisting of a dominant and a submissive pig was selected, based on a feed competition test (FCT) 2 weeks post-weaning. This pair was used in an informed forager test (IFT) which measured aspects of spatial learning and foraging strategies in a competitive context. During individual training, submissive (informed) pigs learned to remember a bait location in a testing arena with 8 buckets (the same bucket was baited in a search visit and a subsequent relocation visit), whereas dominant (non-informed) pigs always found the bait in a random bucket (search visits only). After learning their task, the informed pigs' individual search visit was followed by a pairwise relocation visit in which they were accompanied by the non-informed pig. Effects of pre-weaning housing treatment were not distinctly present regarding the occurrence of aggression in the FCT and the learning performance during individual training in the IFT. During paired visits, informed and non-informed pigs changed their behaviour in response to being tested pairwise instead of individually, but MS and FC pigs showed few distinct behavioural differences.

Behaviors and body weight of suckling piglets in different social environments

OBJECTIVE

This study was conducted to characterize the behaviors and the body weight of suckling piglets in different social environments.

METHODS

Two groups of sows and suckling piglets housed either in individual farrowing crates in separate pens (1.8×2.4 m, the control group) or in groups of three sows with their piglets in farrowing crates in a large common enclosure (5.4×2.2 m, the treatment group) were observed with the aid of video technology for 9 consecutive hours on days 1, 2, and 3, after mixing.

RESULTS

Suckling, agonistic, and elimination behaviors of suckling piglets were significantly higher in the control group than in the treatment group. Inactive behavior was higher in the treatment group than in the control group. Most of the effects of the social environment on the suckling piglets seem to be the result of large reductions in behaviors and body weight for piglets switching from high activity to low activity. Moreover, suckling behavior and birth body weight were highly correlated with body weight at the end of the test.

CONCLUSION

The social environment that resulted from mixing, thus, had significant effects on the behavior and body weight of suckling piglets, and behavioral characteristics, therefore, should be considered when making improvements to the husbandry and care methods used in swine production.

Intermittent suckling with or without co-mingling of non-littermate piglets before weaning improves piglet performance in the immediate post-weaning period when compared with conventional weaning

Background

In this experiment, intermittent suckling (IS) with or without the co-mingling (CoM) of piglets was studied as a method to stimulate solid feed intake and reduce post-weaning stress.

Methods

Three weaning regimes using 30 multiparous sows were compared: (1) conventional weaning (CW) (n = 10 litters), where piglets had continuous access to the sow until weaning (d 0, farrowing = d −25 relative to weaning); (2) intermittent suckling (IS) (n = 10 litters), where piglets were separated from the sow for 8 h/d starting at d −7 (relative to weaning); and (3) intermittent suckling with co-mingling (ISCo) (n = 10 litters) where IS started at d −7 and two litters were housed together during separation and then returned to their original sow. Ad libitum creep feed was available from d −17. At weaning pigs were housed in pens of 11 pigs, 27 pens in total. The ISCo treatment was divided in half to examine effects of different mixing strategies after weaning. Half of the ISCo litters were kept in familiar groups (ISCoF, familiar, n = 4) and the other half were mixed within treatment resulting in groups of unfamiliar pigs (ISCoNF, not familiar, n = 5), the same as IS (n = 9) and CW (n = 9) treatments.

Results

The ISCo piglets ate more creep feed in the week before weaning (P < 0.01), but also showed more aggressive and manipulative behaviour on first day of CoM compared with CW piglets (P < 0.05). IS with or without CoM increased exploratory and play behaviour on the first day of treatment intervention (P < 0.001) and increased sleeping behaviour on the last day of treatment intervention compared with CW (P < 0.001). Mixing strategy at weaning had an effect on performance data with the highest growth and feed intake seen in ISCoF pigs 2 to 8 d after weaning (P <0.001). IS and ISCoNF pigs also grew faster and ate more than CW pigs 2 to 8 d after weaning (P < 0.001). Post-weaning injury scores suggested reduced aggression in ISCo as evidenced by reduced redness (skin irritation) (P < 0.05), and a tendency for ISCo to have less scratches than CW (P < 0.1). The IS pigs slept the most and displayed less manipulative behaviours on the day of weaning and plasma haptoglobin levels remained low in IS pigs after weaning (P ≤ 0.01).

Conclusions

Both intermittent suckling techniques improved production indices in the immediate post-weaning period. However, the addition of co-mingling before weaning in combination with grouping familiar pigs together after weaning improved performance in an additive manner.

Enriched Housing Reduces Disease Susceptibility to Co-Infection with Porcine Reproductive and Respiratory Virus (PRRSV) and Actinobacillus pleuropneumoniae (A. pleuropneumoniae) in Young Pigs

Until today, anti-microbial drugs have been the therapy of choice to combat bacterial diseases. Resistance against antibiotics is of growing concern in man and animals. Stress, caused by demanding environmental conditions, can reduce immune protection in the host, influencing the onset and outcome of infectious diseases. Therefore psychoneuro-immunological intervention may prove to be a successful approach to diminish the impact of diseases and antibiotics use. This study was designed to investigate the effect of social and environmental enrichment on the impact of disease, referred to as "disease susceptibility", in pigs using a co-infection model of PRRSV and A. pleuropneumoniae. Twenty-eight pigs were raised in four pens under barren conditions and twenty-eight other pigs were raised in four pens under enriched conditions. In the enriched pens a combination of established social and environmental enrichment factors were introduced. Two pens of the barren (BH) and two pens of the enriched housed (EH) pigs were infected with PRRSV followed by A. pleuropneumoniae, the other two pens in each housing treatment served as control groups. We tested if differences in disease susceptibility in terms of pathological and clinical outcome were related to the different housing regimes and if this was reflected in differences in behavioural and immunological states of the animals. Enriched housed pigs showed a faster clearance of viral PRRSV RNA in blood serum (p = 0.014) and histologically 2.8 fold less interstitial pneumonia signs in the lungs (p = 0.014). More barren housed than enriched housed pigs developed lesions in the lungs (OR = 19.2, p = 0.048) and the lesions in the barren housed pigs showed a higher total pathologic tissue damage score (p<0.001) than those in enriched housed pigs. EH pigs showed less stress-related behaviour and differed immunologically and clinically from BH pigs. We conclude that enriched housing management reduces disease susceptibility to co-infection of PRRSV and A. pleuropneumoniae in pigs. Enrichment positively influences behavioural state, immunological response and clinical outcome in pigs.

Development of piglets raised in a new multi-litter housing system vs. conventional single-litter housing until 9 weeks of age

This study compared the development until 9 wk of age of piglets raised in either a multi-litter (ML) system or a conventional single-litter (SL) system. The ML system consisted of a multi-suckling system with 5 sows and their litters before weaning, followed by housing in a pen with enrichment in a group of 40 piglets after weaning. In the SL system, piglets were housed with a crated sow before weaning, followed by postweaning housing in groups of 10 littermates in a standard pen. Fifty litters were used in 5 batches and piglets were weaned at 4 wk of age. Preweaning mortality was higher in the ML system than in the SL system (3.22 ± 0.42 vs. 1.52 ± 0.25 piglets per litter, < 0.01), mainly due to crushing before grouping of litters. Litter size at grouping did not differ between systems. ML piglets showed more feed-directed behavior at 2 wk of age (6.80 ± 0.96 vs. 2.35 ± 0.59, < 0.01), suggesting an earlier start of feed exploration, possibly due to social learning from the floor-fed sows and other piglets. Moreover, before weaning, ML piglets showed less damaging oral manipulation (e.g., tail biting) than SL piglets (1.4 ± 0.2 vs. 3.6 ± 0.3 freq/h, < 0.001), which was likely related to the more enriched environment in the ML system. After weaning, ML piglets ate 81% more feed between d 1 and 2 (0.29 ± 0.02 vs. 0.16 ± 0.03 kg/piglet, < 0.01) and had an 82% higher weight gain until d 5 than SL piglets (1.35 ± 0.21 vs. 0.75 ± 0.17 kg, < 0.05) despite a similar weaning weight (ML: 8.4 ± 0.2 kg, SL: 8.3 ± 0.2 kg). Within the first 2 wk after weaning, ML piglets had a lower fecal consistency score (0.27 ± 0.03 vs. 0.39 ± 0.03, < 0.05), indicating a lower occurrence of diarrhea compared with SL piglets. Over the entire 5-wk postweaning phase, ML piglets had a 24% higher weight gain ( < 0.05) and showed more play behavior (4.0 ± 0.3 vs. 2.8 ± 0.3 freq/h, < 0.05) and less damaging oral manipulation (1.8 ± 0.3 vs. 3.5 ± 0.4 freq/h, < 0.01) than SL piglets. These results are probably explained by a combination of the differences in preweaning development, early postweaning performance, and postweaning environment, with a larger and more diverse social group and more physical enrichment in the ML pen. To summarize, provided that preweaning mortality can be reduced, the ML system seems promising for raising robust piglets with better welfare, indicated by a better preweaning behavioral development, improved transition to the postweaning phase, and better postweaning performance.

[Effects of socializing piglets in lactation on behaviour, including tail-biting, in growing and finishing pigs]

OBJECTIVE

The aim of this study was to determine whether early socialising of piglets influences the later behaviour and the risk of tail biting in growing and finishing pigs.

MATERIAL AND METHODS

The behaviour of 183 animals (divided in three successive runs) was recorded from birth until the end of the fattening period. Furthermore, the condition of the teats of the sows as well as the integument and tails of the growing and finishing pigs were evaluated. To socialize the piglets, four litters of the experimental group (V) were provided with additional space (walkway) by opening "piglet-doors" (day 10 postpartum of the youngest litter). The piglets of the control group (K) were reared in conventional farrowing crates located in the same compartment of the stable. Post-weaning, the piglets were assigned to three groups: the experimental group (V/V, two litters of group V), the control group (K/K, two litters of group K) and the mixed group (V/K, one litter of group V and one litter of group K).

RESULTS

After opening the "piglet-doors", piglets of group V displayed significantly more playing behaviour than piglets of group K. Additionally, the agonistic behaviour increased in group V. Post-weaning, at allocation and mixing, animals of group V/V showed significantly less agonistic behaviour than pigs of group K/K. Tail-biting behaviour occurred in all three groups, but only in runs two and three. On the 100th day of the fattening period, 58.7% of the pigs of group V/V, 51.7% of group V/K and 43.3% of group K/K still had intact tails. In pigs of group K/K, the tails were significantly shorter compared to the other two groups.

CONCLUSION AND CLINICAL RELEVANCE

Early socialization enhances piglet welfare in farrowing pens by encouraging playing behaviour. Less agonistic behaviour at allocation could furthermore reduce stress at mixing and allocation. The aim to reduce the incidence of tail-biting could not be achieved. However, socializing piglets in lactation could contribute, in accordance with other measures, to an influence on biting behaviour.

Effects of Oxytocin Administration on the Response of Piglets to Weaning

Simple Summary

Weaning is a stressful milestone for domestic animals. It is often performed at an early age and as an abrupt change in comparison to the transitional period seen in feral or wild animals. Oxytocin, a hormone associated with attachment, could improve the response of piglets to weaning. Piglets were either given oxytocin intranasally, subcutaneously, or handled as controls. Oxytocin had no effect on the physiological response to weaning. However, oxytocin increased the frequency of mild aggressive social behaviors between OT-administered and control pigs. Hence, the use of a single administration of oxytocin prior to weaning in pigs is not recommended.

Abstract

Weaning is often an abrupt and stressful process. We studied the effects of administering oxytocin, subcutaneously or intranasally, on the ability of pigs to cope with weaning. On a commercial farm 144, 30 day-old pigs from 24 litters were used. On the day of weaning, one male and one female in each litter were administered one of three treatments: intranasal oxytocin (24 International Unit), subcutaneous oxytocin (10 International Unit per kg of body weight), or handled as a control. The pigs were placed in one of eight weaner pens, split by sex and with an equal representation of treatments. Data included body weight and growth, physiology (neutrophil:lymphocyte ratio, plasma cortisol, C-reactive protein and Tumor Necrosis Factor-α concentrations), and behavior (feeding, drinking, social behavior). Both oxytocin treatments tended to result in higher levels of mild aggression within groups (p = 0.08), specifically between oxytocin-administered and control pigs (subcutaneous to control p = 0.03; intranasal to control p = 0.10). Subcutaneously-administered pigs tended to frequent the feeder more often than intranasally-administered pigs (p < 0.10), with the latter having slightly lower body weight 38 days post-weaning (p = 0.03). However, acute oxytocin administration did not result in any noticeable physiological changes 4 or 28 h post-weaning. Hence, the use of a single administration of oxytocin prior to weaning in pigs is not recommended, at least not in the conditions studied here.

Does the environmental background (intensive v. outdoor systems) influence the behaviour of piglets at weaning?

Under intensive pig husbandry, outdoor systems offer a more complex physical and social environment compared with indoor systems (farrowing sheds). As the rearing environment affects behavioural development, it can, therefore, influence behavioural responses of pigs to stressful environments in later stages of production. We tested how the rearing environment influenced behavioural responses to a novel arena test in piglets on the day that they were weaned and mixed into large groups. We recorded video footage and compared the behavioural responses of 30 outdoor-raised and 30 farrowing shed-raised piglets tested in an experimental arena and sequentially exposed to four challenges (each for 5 min) on the day of weaning. Quantitative and qualitative behavioural measures were recorded using time budgets and scoring demeanour or 'qualitative behavioural expression' (using Qualitative Behavioural Assessment (QBA)). When held in isolation (challenge 1), both groups were scored as more 'scared/worried', while outdoor-raised piglets spent more time eating and jumping against the arena walls. Both groups interacted with a plastic ball (challenge 2: exposure to a novel object) during which they were scored as more 'playful/curious' than other challenges. When a food bowl was introduced (challenge 3), farrowing shed-raised piglets were more interested in playing with the food bowl itself, whereas outdoor-raised piglets spent more time eating the feed. Finally, there were no significant differences in social behaviour (challenge 4: introduction of another piglet) between the two groups in terms of the latency to contact each other, amount of time recorded engaged in aggressive/non-aggressive social interactions or QBA scores. Although piglets spent 30% of their time interacting with the other piglet, and half of this time (47%) was engaged in negative interactions (pushing, biting), the levels of aggression were not different between the two groups. Overall, outdoor-raised piglets ate more and were scored as more 'calm/passive', whereas farrowing shed-raised piglets spent more time investigating their environment and were scored as more 'playful/inquisitive'. In conclusion, we did not find differences in behaviour between outdoor-raised and farrowing shed-raised piglets that would highlight welfare issues. The differences found in this study may reflect conflicting affective states, with responses to confinement, neophobia and motivation for exploration evident.

A review of sow and piglet behaviour and performance in group housing systems for lactating sows

Commercial use of group housing systems for lactating sows is limited, but the recent transition to group housing during gestation in the EU may result in a renewed interest in such systems. Therefore, this review aims to identify key factors that may contribute to the success or failure of group housing of lactating sows in comparison with individual housing by describing the variety in group housing systems and discussing animal behaviour and performance compared with individual housing. Group housing systems can be divided in multi-suckling (MS) systems, in which sows are grouped with their litters, and get-away (GA) systems, which include a separate communal area accessible to sows only. These systems differ in many aspects regarding management and layout but, compared with individual housing, generally provide more environmental complexity, more freedom of movement for the sows and more freedom to express behaviours related to, for example, maternal care and social interactions. Group housing poses several risks, such as disrupted nursing and an increased level of crushing during the MS phase, and in the GA systems there is a risk for early cessation of nursing. On the other hand, pre-weaning mingling of litters clearly benefits piglet social development and may improve adaptation to the post-weaning situation. In addition, group-housed sows may show lactational ovulation, which provides opportunities for insemination during an extended lactation period, which benefits the piglets. Gradual transitions in social and physical environment around gestation, farrowing, grouping and weaning seem to be key success factors for group housing systems during lactation. In addition, selection of suitable sows and quality of stockmanship seem important.

Group housing for lactating sows with electronically controlled crates: 1. Reproductive traits, body condition, and feed intake

The aim was to compare a group housing system (GROUP) and a conventional single housing (SINGLE) for lactating sows with regard to the performance of sows and piglets. Data of 132 cross-breed sows were collected in 11 batches with 6 sows in GROUP and SINGLE in each batch. The GROUP had single pens (4.7 m(2)) with electronically controlled crates and a shared running area (13 m(2)). The sows in GROUP were retained in the crates 3 d prepartum until 1 d postpartum. Piglets were able to leave the single pens on d 5 postpartum. Recorded traits per litter included the number of piglets born alive and weaned, piglet losses, and individual BW at birth and weaning. In addition, body condition and back fat thickness before and after lactation (26 d) and the daily feed intake of the sows were measured. Gilts and sows were analyzed separately. The reproductive traits did not differ significantly (P > 0.05) between the farrowing systems with exception of the weaning weights (GROUP = 7.6 ± 0.12 kg vs. SINGLE = 8.1 ± 0.12 kg; P < 0.05). Group housed and SINGLE sows had 14.4 ± 0.47 and 14.6 ± 0.45 piglets born alive, respectively. In both housing systems, sows weaned 11.4 piglets (SEM = 0.14 and 0.13 for GROUP and SINGLE), respectively. Most piglet losses (72%) occurred during the first 3 d postpartum. At this point in time, piglets in GROUP and SINGLE were housed in single pens. In the single pens, GROUP sows could leave the farrowing crate whereas SINGLE sows were fixed in crates during the whole lactation. In total, piglet losses were not significantly different during lactation between GROUP and SINGLE treatments (2.2 ± 0.05 and 2.4 ± 0.05 piglets per litter, respectively). Sows housed in GROUP had a significantly lower (P < 0.05) BCS (2.2 ± 0.05) after lactation compared with SINGLE sows (BCS = 2.4 ± 0.05). This development could not be verified using the back fat thickness value at weaning (GROUP = 14.4 ± 0.25 mm vs. SINGLE = 14.6 ± 0.23 mm). Daily feed intake was significantly greater for GROUP sows (6.4 ± 0.08 kg per day) than SINGLE sows (6.15 ± 0.08 kg per day; P < 0.05). In conclusion, the performance of GROUP and SINGLE sows was similar with the exception of lighter weaning weights in GROUP housing.