The effect of agonistic interactions on the heart rate of group-housed sows

Social encounters produce different autonomic response between dominants and subordinates in crows

Recent studies of behavioural physiology on animals have suggested the crucial role of peripherally physiological signals in eliciting arousal and emotion. Heart rate (HR) is one of the useful and critical signals to measure autonomic regulation as a physiological basis for arousal and emotion in response to biologically significant stimuli such as social encounter with conspecific individuals. However, our understanding of peripherally physiological response such as HRs and autonomic activities under social contexts of non-human animals is still limited, particularly in birds. Here, we examined the autonomic activity of behaving crows exposed to a dominant and a subordinate conspecific by using non-invasive electrocardiogram recording. We found different patterns of autonomic responses dependent on the relative dominance position: dominant crows encountering subordinates showed the elevation of sympathetic activity, whereas subordinates encountering dominants showed decreased HR with elevated parasympathetic activity. This is the first study in birds to report different autonomic responses dependent on relative dominance positions during dyadic social encounters. The present study advances our understanding of the role of the peripheral autonomic system, as an interactive system with the brain, in eliciting emotion/arousal associated with socially challenging environments from an evolutionary perspective.

Social behavior in farm animals: Applying fundamental theory to improve animal welfare

A fundamental understanding of behavior is essential to improving the welfare of billions of farm animals around the world. Despite living in an environment managed by humans, farm animals are still capable of making important behavioral decisions that influence welfare. In this review, we focus on social interactions as perhaps the most dynamic and challenging aspects of the lives of farm animals. Social stress is a leading welfare concern in livestock, and substantial variation in social behavior is seen at the individual and group level. Here, we consider how a fundamental understanding of social behavior can be used to: (i) understand agonistic and affiliative interactions in farm animals; (ii) identify how artificial environments influence social behavior and impact welfare; and (iii) provide insights into the mechanisms and development of social behavior. We conclude by highlighting opportunities to build on previous work and suggest potential fundamental hypotheses of applied relevance. Key areas for further research could include identifying the welfare benefits of socio–positive interactions, the potential impacts of disrupting important social bonds, and the role of skill in allowing farm animals to navigate competitive and positive social interactions. Such studies should provide insights to improve the welfare of farm animals, while also being applicable to other contexts, such as zoos and laboratories.

Animal Welfare and the Acknowledgment of Cultural Differences

Simple Summary

Most pigs worldwide are in modern, commercial, indoor farms. There is debate on whether or not modern pig production systems meet all the needs of the animals. Pigs are able to perceive and feel and have mental capabilities that warrant attention to their welfare. The degree of on-farm animal welfare oversight varies around the world. Science is used to set animal welfare rules. However, science sometimes conflicts with cultural values (ex., religious slaughter). The focus of many animal welfare rules do not address the most significant problems on modern commercial pig farms. We believe that we should use science to determine the animal welfare needs of farm pigs but with a healthy respect for cultural differences in the ethics of animal care. We should also prevent economic neo-colonialism from forcing Western views on other cultures.

Abstract

Pigs are considered sentient beings that have a mental capability that warrants attention to their welfare. Cultural values towards animal welfare differ in world regions. Still, authors have argued for worldwide harmonization of animal welfare rules. At the same time, the focus of many animal welfare rules do not address the most significant problems on modern commercial pig farms. The foci of animal welfare rules are often on space (quantity and quality), acute painful practices, equipment, and caretaker behavior. However, most serious animal welfare issues are related to episodic events such as compromised pigs, lack of appropriately skilled staff, and human behavior (or lack thereof) towards animals. Modern technologies such as image, sound, and building oversight by automated systems can potentially provide better individual pig care. The future should bring us solutions to identify and resolve episodic negative animal welfare events. The other issues of space and painful practices are best improved by using science-based solutions. We propose that science be the key resource to making animal welfare decisions, but with a healthy appreciation and respect for cultural differences in our views of animals and the economic impact of rules. Colonialism is not viewed positively today, and economic neo-colonialism should not be allowed to replace it. Respect for cultural differences should play a role in animal welfare rules within and among countries.

Heart rate as a measure of emotional arousal in evolutionary biology

How individuals interact with their environment and respond to changes is a key area of research in evolutionary biology. A physiological parameter that provides an instant proxy for the activation of the automatic nervous system, and can be measured relatively easily, is modulation of heart rate. Over the past four decades, heart rate has been used to assess emotional arousal in non-human animals in a variety of contexts, including social behaviour, animal cognition, animal welfare and animal personality. In this review, I summarize how measuring heart rate has provided new insights into how social animals cope with challenges in their environment. I assess the advantages and limitations of different technologies used to measure heart rate in this context, including wearable heart rate belts and implantable transmitters, and provide an overview of prospective research avenues using established and new technologies, with a special focus on implications for applied research on animal welfare. This article is part of the theme issue 'Measuring physiology in free-living animals (Part II)'.

Feeding Strategies Before and at Mixing: The Effect on Sow Aggression and Behavior

Simple Summary

Sows in domestic settings are often mixed into new groups of animals, resulting in the need to form hierarchies, causing aggression and related stress. Restrictively fed gestating sows are unlikely to be sated, and are more likely to view food as a limited resource and to be frustrated and aggressive. Creating satiety in sows as they are mixed may be a simple method to reduce mixing aggression. This experiment assessed the provision of different diets; a standard diet (CON) or high (HI) volume of a “standard” diet, or a diet enhanced with lignocellulose (fiber source) fed before mixing (LC) and at mixing (LCM), was studied. There were treatment effects on fight duration, the number of fights, injuries, condition scores, and time spent eating and drinking. These results suggest that feeding a diet containing 2.5% lignocellulose and a standard diet at a high feeding level for four days post-mixing may affect overall aggression within groups and sow satiety levels. Our data found decreased fight numbers and increased fight duration in the LCM compared to the LC treatment, and therefore, feeding the fiber source before mixing affects aggression levels differently than when fed just after mixing. A further understanding of different fiber sources and how their properties affect digestion and sow satiety would enable critical evaluation and use of fiber sources for benefit in reducing aggression at mixing.

Abstract

Hierarchy formation in domestic sows results in aggression and stress, which might be ameliorated through nutritional satiety. The effect on aggression in group housed, gestating sows provided a standard or high volume of a “standard” diet, or diet enhanced with lignocellulose before, at, and after mixing was studied. Ninety-six Large White cross Landrace weaned sows were allocated to: control diet (CON), high volume diet (HI), and lignocellulose-enhanced diet before and at mixing (LC), and after mixing (LCM) (24 sows per treatment). Sows were housed in stalls for 10 days before mixing, when the CON, HI, and LCM groups were fed a standard diet, and in the LC group, a diet enhanced with lignocellulose at 2.5% was given. At mixing, the CON group continued on a standard diet at 2.5 kg/sow per day, HI were fed the standard diet at 4 kg/sow per day for the first four days and 2.5 kg/sow per day thereafter, and LC and LCM were fed the lignocellulose-enhanced diet at 2.5 kg/sow per day. Behavior, salivary cortisol concentrations, lesion number, and condition were recorded on M0, M1, M6, and M14. Reproduction was assessed using pregnancy rate and progesterone measurements. There were several treatment effects on aggression in the sows following mixing. There were significantly lower fight numbers (CON = 0.34 ± 0.03 Log (1 + x) transformed mean and SEM (1.49 untransformed adjusted mean), LC = 0.31 ± 0.04 (1.14), LCM = 0.42 ± 0.04 (0.28), HI = 0.35 ± 0.04 (1.64); p = 0.001) and longer individual fight durations in the LCM group compared to the CON and LC group (CON = 0.88 s ± 0.07 Log transformed mean and SEM (10.31 s, untransformed adjusted mean), LC = 0.89 ± 0.09 (13.51), LCM = 1.16 ± 0.07 (21.43), HI = 01.03 ± 0.07 (16.42); p = 0.04), and overall higher injury numbers in the LC and LCM groups than the HI. Time spent eating was significantly lower in the CON group than both HI and LC (CON = 7.79 ± 0.37, LC = 8.91 ± 0.38, LCM = 8.49 ± 0.42, HI = 9.55 ± 0.39; p = 0.007). The time spent drinking was also affected by treatment, with more time spent drinking in CON than LC (p = 0.024). The condition score of the sows was affected by diet, with higher condition scores in the HI group than LCM and LC (CON = 2.98 ± 0.11, LC = 2.75 ± 0.10, LCM = 2.74 ± 0.10, HI = 3.12 ± 0.10; p = 0.017). These results suggest that feeding a diet containing 2.5% lignocellulose and a standard diet at a high feeding level for four days post-mixing may affect overall aggression and possibly satiety levels. Our data found decreased fight numbers and increased fight duration in the LCM compared to the LC treatment, and therefore, feeding the fiber source before mixing affects aggression levels differently than when fed just after mixing. A further understanding of different fiber sources and how their physiochemical properties affect digestion and sow satiety would enable critical evaluation and use of fiber sources for benefits in reducing aggression at mixing.

Social network properties predict chronic aggression in commercial pig systems

Post-mixing aggression in pigs is a harmful and costly behaviour which negatively impacts both animal welfare and farm efficiency. There is vast unexplained variation in the amount of acute and chronic aggression that dyadic behaviours do not fully explain. This study hypothesised that certain pen-level network properties may improve prediction of lesion outcomes due to the incorporation of indirect social interactions that are not captured by dyadic traits. Utilising current SNA theory, we investigate whether pen-level network properties affect the number of aggression-related injuries at 24 hours and 3 weeks post-mixing (24hr-PM and 3wk-PM). Furthermore we compare the predictive value of network properties to conventional dyadic traits. A total of 78 pens were video recorded for 24hr post-mixing. Each aggressive interaction that occurred during this time period was used to construct the pen-level networks. The relationships between network properties at 24hr and the pen level injuries at 24hr-PM and 3wk-PM were analysed using mixed models and verified using permutation tests. The results revealed that network properties at 24hr could predict long term aggression (3wk-PM) better than dyadic traits. Specifically, large clique formation in the first 24hr-PM predicted fewer injuries at 3wk-PM and high betweenness centralisation at 24hr-PM predicted increased rates of injury at 3wk-PM. This study demonstrates that network properties present during the first 24hr-PM have predictive value for chronic aggression, and have potential to allow identification and intervention for at risk groups.

Effect of Floor Cooling on Behavior and Heart Rate of Late Lactation Sows Under Acute Heat Stress

Much U.S. swine production is in Köppen climate types classified as "hot-summer humid continental" and "humid subtropical." As a result, farrowing sows are often exposed to temperatures above their upper critical temperature. This heat stress (HS) can affect sow welfare and productivity and have a negative economic impact. The study objective was to evaluate the impact of a cooling pad on sows' behavioral and heart rate responses to acute HS. Treatments were randomly allotted to ten multiparous sows to receive a constant cool water flow of 0.00 (CONTROL, n = 4), 0.25 (LOW, n = 2), 0.55 (MEDIUM, n = 2), or 0.85 (HIGH, n = 2) L/min for 100 min and replicated eight times, switching treatments so that each sow was exposed to each treatment. The cooling was initiated 1 h after the room reached 35°C for 100 min. Eating, drinking and nursing behaviors, postures, and heart rate were recorded before heating (Period 1), prior to cooling (Period 2), and during cooling (Period 3). There were no differences between LOW, MEDIUM, and HIGH flow rates for any periods on all behavioral and heart rate traits, so data were pooled (COOLED). There were no differences in any of the measures during Periods 1 and 2, except for the ratio of short term to long term heart rate variability (SD1:SD2) with higher values for CONTROL than COOLED sows in Period 2. During Period 3, CONTROL sows changed postures more frequently (11.5 ±1.6 vs. 5.1 ±1.6 changes per hour), spent more time drinker-pressing/drinking (4.4 ± 0.5 vs. 1.4 ± 0.4% of time), standing (6.6 ± 1.7 vs. 3.8 ± 1.6% of time), sitting (10.0 ± 1.2 vs. 4.0 ± 1.1), less time lying (83.0 ±1.8 vs. 92.0 ±1.7% of time), especially lying laterally (62.0 ± 5.6 vs. 75.0 ± 5.3% of time), than sows in all three cooling treatments (all P < 0.001). Heart rate during Period 3 was lower for COOLED sows compared to the CONTROL sows (100.2 ± 3.4 vs. 119.0 ± 4.0 beat per min, P < 0.001). Sows response to increased thermal load can be effectively reduced using water-cooled cooling pads, thereby improving sow comfort and welfare. The beneficial effects on behavior are noticeable from the lowest flow rate.

Mixing induces long-term hyperthermia in growing pigs

The purpose of this experiment was to determine whether body temperature is a sensitive parameter to measure long-term effects of stress in pigs. Mixing of unacquainted pigs is a severe stressor that has detrimental effects on health, production and welfare. We measured deep body temperature after mixing growing pigs. Five pigs of 15 weeks of age, each individually housed with a companion pig, were mixed with two unacquainted congeners. Deep body temperature, heart rate and activity were recorded by radiotelemetry 9 days prior to until 8 days after mixing. These parameters were also recorded in five control pigs (individually housed with a companion pig) during the same time span. Behaviour during the light period was recorded on videotape on the day of mixing and on three subsequent days. Mixing induced a significant rise in body temperature that lasted for 8 h after mixing. Although heart rate and general activity level did not significantly differ between mixed and control pigs, mixing significantly increased the frequency of fighting and reduced the frequency of eating. In conclusion, the present experiment shows that mixing induces a long-lasting hyperthermia in pigs. Thus, deep body temperature may be used as a sensitive parameter to measure long-term effects of stress in pigs.

Influence of housing system during gestation on the behaviour and welfare of gilts in farrowing crates

There is some evidence to show that loose housing during gestation has a negative influence on the welfare of sows subsequently in farrowing crates. However, little is known about the effects of the gestation housing on the initial responses of gilts to the farrowing crate or of the effects on gilt welfare throughout lactation. The objective of this experiment was to evaluate three gestation housing systems (1) stalls (ST); (2) loose-bedded (LB) and (3) loose-unbedded (LU) pens for their effect on behaviour, heart rate and skin lesion scores of gilts in farrowing crates. During the 1st h in the farrowing crate, LB gilts were more active, while ST gilts were more vocal. Although heart rates during the 1st h did not differ significantly between treatments, LB and LU gilts had significantly higher mean heart rates during the first 5 min in the crate, compared with 35 min later. Posture changes during the first 24 h did not differ between treatments. However, there was a significant reduction in the number of posture changes made by ST gilts but not LB or LU gilts by day 8. Increases in the skin lesion score of gilts in all three treatments were observed after 24 h in the crate, further increases were observed post farrowing in both loose treatments. Although no significant differences in the skin lesion score were observed during lactation, LB gilts were weaned with lower lesion scores than LU or ST gilts. Gilts from both loose treatments experienced greater distress at first introduction to the farrowing crate. However, the change in environment also had an adverse affect on the welfare of ST gilts. Skin damage and continuing discomfort of the loose-housed gilts post farrowing suggests that they experienced more stress at parturition. Bedding during gestation had a beneficial effect on skin health in the farrowing crate that persisted until weaning.

Genetic associations of short- and long-term aggressiveness identified by skin lesion with growth, feed efficiency, and carcass characteristics in growing pigs

The objective of this study was to investigate the genetic relationships between skin lesion traits in group housed growing pigs as a measure of short- (in a newly mixed group) and long- (in a socially stable group) term aggression and commonly used commercial performance measures: growth, feed intake, feed efficiency, and carcass traits. Data on 2,413 growing pigs (138 groups) were available. Pigs were mixed into new social groups of 18 animals, and skin lesions were counted 24 h (SL24h) and 5 wk (SL5wk) postmixing. The animal model was used to estimate genetic parameters for skin lesion traits, test daily gain, lifetime daily gain, daily feed intake, feed efficiency (calculated as test daily gain divided by daily feed intake), loin depth, back fat, and HCW. Skin lesions had a heritable component, ranging from 0.08 for anterior SL24h to 0.22 for central SL5wk and would, therefore, be suitable as a method of phenotyping aggression for selection purposes. Significant positive genetic correlations were found between SL24h and SL5wk (0.46 to 0.81). Positive genetic correlations were also found between SL24h (central and posterior body regions) or SL5wk (all body regions) and the production traits lifetime daily gain, test daily gain, and HCW (0.29 to 0.54). Central SL24h, anterior SL5wk, and posterior SL5wk were found to correlate positively with feed efficiency (0.39 to 0.50), suggesting that pigs with more lesions convert feed more efficiently. Where significant, the magnitude of phenotypic correlations was low but positive (0.07 to 0.10). These results suggest that, genetically, animals that receive many lesions show improved performance compared to those with few lesions, except for anterior SL24h, which had previously been shown to be genetically positively correlated with the initiation of nonreciprocal attacks. It may, therefore, be possible, via selection against anterior skin lesions at mixing, to reduce this form of 1-sided aggression without adversely affecting production traits.

Impact of group housing of pregnant sows on health

Group housing of sows during gestation is mandatory in the EU since 2013. Compared to housing in individual crates, group housing allows the animals to express normal activity and behavior. The present paper discusses the impact of group housing on health, with emphasis on lameness, aggression and possible spread of infectious diseases. The prevalence of lameness is generally higher in sows housed in group than in sows housed individually. Floor space per sow, group size, pen design and flooring are the main factors of group housing involved in lameness development. Especially floor characteristics are important, and particular attention should be paid to the type, building material and quality of the floor, hygiene and the use of bedding such as straw or rubber mats. Aggression between sows is another critical issue in group housing systems. It occurs predominantly because of competition for access to a limited resource, or to establish a social hierarchy. Key factors to prevent aggression in group housing include gradual familiarization of unfamiliar animals, sufficient space and pen structure during initial mixing, minimizing opportunities for dominant sows to steal food from subordinates, provision of a good quality floor, environmental enrichment and use of straw bedding. Very scarce evidence-based information is available on the relationship between group housing and infectious disease. Compared to individual housing, sows in group housing have more nose-to-nose contact, and they have more oral contact with feces and urine. These factors could contribute to a higher or faster transmission of pathogens, but so far, there is no evidence showing more disease problems in group housing systems. In conclusion, in group housing systems, particular attention should be paid to prevention of lameness and aggression. Management is crucial but also feeding strategies, floor and bedding, and design of housing are very important as relatively minor adjustments may exert major effects on the animals.

Social stress as a cause of diseases in farm animals: Current knowledge and future directions

Over the past 50 years, biomedical research has established a strong linkage between psychosocial stress and disease risk in humans, which has transformed the understanding of stress and the role it plays in human lives. This research has led to personalized medicine where a reduction in daily life stress is a main goal for many people with debilitating illnesses. This review describes the supporting evidence that social stress also plays a critical role in farm animal disease prevention, and may be a mediator by which common management practices can increase disease risk. There is evidence that social factors, including deprivation of social contact ('social isolation'), reducing space allowance ('crowding') and disturbing social order ('social instability') trigger physiological and behavioral indicators of stress in livestock. Less research exists, however, linking management practices that trigger social stress with higher disease risk. Suggestions are offered for future research opportunities, and practical, evidence-based recommendations are made for reducing the negative effects of social isolation, instability and crowding. The current evidence that social factors contribute to disease risk in farm animals is not as convincing as the human literature, but remains a promising and important area for future research.

Mother's exercise during pregnancy programmes vasomotor function in adult offspring

The intrauterine environment is influenced by maternal behaviour and programmes atherosclerotic disease susceptibility in offspring. The aim of this investigation was to test the hypothesis that mothers' exercise during pregnancy improves endothelial function in 3-, 5- and 9-month-old porcine offspring. The pregnant sows in the exercise group ran for an average of 39.35 ± 0.75 min at 4.81 ± 0.35 km h(-1) each day for 5 days per week for all but the last week of gestation. This induced a significant reduction in resting heart rate (exercised group, 89.3 ± 3.5 beats min(-1); sedentary group, 102.1 ± 3.1 beats min(-1); P < 0.05) but no significant differences in gestational weight gain (65.8 ± 2.1 versus 63.3 ± 1.9%). No significant effect on bradykinin-induced vasorelaxation with and without l-NAME was observed. A significant main effect was identified on sodium nitroprusside-induced vasorelaxation (P = 0.01), manifested by a reduced response in femoral arteries of all age groups from exercised-trained swine. Nitric oxide signalling was not affected by maternal exercise. Protein expression of MYPT1 was reduced in femoral arteries from 3-month-old offspring of exercised animals. A significant interaction was observed for PPP1R14A (P < 0.05) transcript abundance and its protein product CPI-17. In conclusion, pregnant swine are able to complete an exercise-training protocol that matches the current recommendations for pregnant women. Gestational exercise is a potent stimulus for programming vascular smooth muscle relaxation in adult offspring. Specifically, exercise training for the finite duration of pregnancy decreases vascular smooth muscle responsiveness in adult offspring to an exogenous nitric oxide donor.

Effects of dietary L-carnitine and ractopamine HCl on the metabolic response to handling in finishing pigs

Two experiments (384 pigs; C22 × L326; PIC) were conducted to determine the interactive effect of dietary L-carnitine and ractopamine HCl (RAC) on the metabolic response of pigs to handling. Experiments were arranged as split-split plots with handling as the main plot and diets as subplots (4 pens per treatment). Dietary L-carnitine (0 or 50 mg/kg) was fed from 36.0 kg to the end of the experiments (118 kg), and RAC (0 or 20 mg/kg) was fed the last 4 wk of each experiment. At the end of each experiment, 4 pigs per pen were assigned to 1 of 2 handling treatments. Gently handled pigs were moved at a moderate walking pace 3 times through a 50-m course and up and down a 15° loading ramp. Aggressively handled pigs were moved as fast as possible 3 times through the same course, but up and down a 30° ramp, and shocked 3 times with an electrical prod. Blood was collected immediately before and after handling in Exp. 1 and immediately after and 1 h after handling in Exp. 2. Feeding RAC increased (P < 0.01) ADG and G:F, but there was no effect (P > 0.10) of L-carnitine on growth performance. In Exp. 1 and 2, aggressive handling increased (P < 0.01) blood lactate dehydrogenase (LDH), lactate, cortisol, and rectal temperature and decreased blood pH. In Exp. 1, there was a RAC × handling interaction (P < 0.06) for the difference in pre- and posthandling blood pH and rectal temperature. Aggressively handled pigs fed RAC had decreased blood pH and increased rectal temperature compared with gently handled pigs, demonstrating the validity of the handling model. Pigs fed RAC had increased (P < 0.01) LDH compared with pigs not fed RAC. Pigs fed L-carnitine had increased (P < 0.03) lactate compared with pigs not fed L-carnitine. In Exp. 2, pigs fed RAC had lower (P < 0.02) blood pH immediately after handling, but pH returned to control levels by 1 h posthandling. Lactate, LDH, cortisol, and rectal temperature changes from immediately posthandling to 1 h posthandling were not different (P > 0.10) between pigs fed L-carnitine and those fed RAC, indicating that L-carnitine did not decrease recovery time of pigs subjected to aggressive handling. These results suggest that pigs fed 20 mg/kg of RAC are more susceptible to stress when handled aggressively compared with pigs not fed RAC. Dietary L-carnitine fed in combination with RAC did not alleviate the effects of stress. This research emphasizes the importance of using proper animal handling techniques when marketing finishing pigs fed RAC.

The effects of dietary chromium(III) picolinate on growth performance, vital signs, and blood measurements of pigs during immune stress

This experiment used 24 pigs (26.0 kg) to investigate the effects of dietary chromium (Cr) on pigs challenged with lipopolysaccharide (LPS). Following 35 days of diet exposure, the immune stress treatments were: (1) phosphate-buffered saline (PBS) injection and no Cr, (2) LPS injection and no Cr, (3) LPS injection and Cr 1,000 ppb, and (4) LPS injection and Cr 2,000 ppb. At 0 h, PBS or LPS was injected intraperitoneally in each pig. During the first 12 h post-injection, pigs challenged with LPS lost 951 g, while the PBS group gained 170 g (p < 0.001). Compared with the PBS group, LPS-challenged pigs consumed less feed (p < 0.01) during the first 24 h. The LPS group had higher rectal temperature at 2 and 4 h and higher respiratory rate at 1.3 and 8.5 h than the PBS group (p < 0.05). Plasma collected at 3 h had higher cortisol (p < 0.001) and lower glucose (p < 0.05) concentrations in the LPS group than the PBS group. However, supplemental Cr did not affect the response variables. Overall, the LPS challenge affects growth performance, vital signs, and plasma variables, but dietary Cr is unable to moderate stress-related effects associated with an LPS challenge.

Heart rate modulation in bystanding geese watching social and non-social events

Simply observing other individuals interacting has been shown to affect subsequent behaviour and also hormones in 'bystander' individuals. However, immediate physiological responses of an observer have been hardly investigated. Here we present results on individuals' heart rate (HR) responses during various situations, which occur regularly in a flock of greylag geese (Anser anser, e.g. agonistic encounters, vehicles passing by). We recorded simultaneously HR and behaviour of 21 semi-tame free-roaming geese, equipped with fully implanted transmitters. We considered 304 social and 81 non-social events during which the focal individuals did not respond behaviourally. Independent of the spatial distance to the event, these HR responses were significantly greater in social contexts (e.g. departing or landing geese, agonistic interactions) than in non-social situations (e.g. vehicles passing by, thunder). Focal individuals showed a significantly higher maximum HR as well as a greater HR increase in response to agonistic interactions, in which the pair partner or a family member was involved, as compared with a non-affiliated goose. Also, HR was significantly higher when the bystander watched non-affiliated geese interacting, which were higher ranking than the focal. We conclude that these differences are due to different relevance of the recorded events for the focal individual, depending on the individuals involved in the observed interaction.

Housing during early pregnancy affects fertility and behaviour of sows

From 1.1.2013 EU legislation will permit stall-housing of dry sows for only 4 weeks post-service. Stalls are associated with compromised animal welfare, but group housing comes with risks from social confrontations. Studies on housing effects on fertility have produced contradictory results as systems are inconsistently defined. Effects of housing on pregnancy rate 28 days post-service (P28), early disruption of pregnancy (EDP) and behaviour were investigated in 12 replicates of 40 sows. Half of the animals were stalled (treatment S, mean parity 2.4) and half group-housed adjacent on 5.1 m(2) deep litter per sow (treatment G, mean parity 2.3). Pregnancy was detected using real-time ultrasound. An EDP-diagnosis required a drop of salivary progesterone concentration from >15.9 to <15.9 mmol/l in a series of samples taken on days 17, 20, 24 and 27 post-service. Behaviour was scan sampled on day 27 for 120 min with 10-min intervals. Data was analysed using mixed regression models in MLwiN. Treatment S increased the odds for P28 with 2.3 and the pregnancy rate of a treatment group with 0.1 compared with G. G increased the odds for EDP with 4.6. Treatment did not affect total exploratory or total passive behaviour. S sows explored floor and fixtures (not bedding) more and performed more passive sitting than G sows. Social stress may have caused the impaired reproductive performance in G sows. S sows showed behavioural signs of decreased welfare, but no corresponding reproductive effects. An interdisciplinary approach is needed when evaluating the appropriateness of housing systems.

Effects of boar presence on agonistic behavior, shoulder scratches, and stress response of bred sows at mixing

The objective of this study was to determine the effects of boar presence on aggression, shoulder scratches, and salivary cortisol in group-housed sows during the period after mixing, which is when dominance hierarchies are formed. A total of 225 York-shire sows were used. Five groups of 15 sows were each exposed to 1 of 3 levels of boar presence (n = 15): physical (boar in pen with sows; 2.15 m2 per sow), fenceline (boar housed adjacent to sows; 2.3 m2 per sow), or control (no boar in the room; 2.3 m2 per sow). The experiment was divided into 2 phases. In phase 1, behavioral measurements were taken for 48 h after mixing and boar introduction. In phase 2, behavioral measurements were taken beginning on d 6 after mixing and included 24 h before and 48 h after boar removal. In phases 1 and 2, shoulder scratches were scored 24 h before and 24 h after mixing and boar removal, respectively. Saliva samples were collected each morning (0600 to 0700) and afternoon (1600 to 1700) during both phases. Frequencies of intersow aggressive contact (bite, body knock, and head knock) and threats as well as frequencies and durations of fighting bouts were determined from video recordings during daily feeding (49.6 +/- 1.4 min) and nonfeeding (21 +/- 0.2 h) periods. During phase 1, boar presence did not affect the frequency of threats during either the feeding or nonfeeding periods. Control groups had fewer aggressive contacts at feeding during the 25- to 48-h period compared with the fenceline groups (P = 0.01). Total duration of fighting and average fighting bout duration were unaffected by treatment. However, the number of fights occurring during feeding 25 to 48 h postmixing was lower in the physical groups than in the fenceline groups (P = 0.023); measures for the control groups were intermediate. Physical sows also received fewer shoulder scratches postmixing than did control sows (P = 0.048). After mixing, physical sows showed greater morning (P = 0.08) and afternoon (6 h postmixing, P = 0.01; 32 h postmixing, P = 0.08) salivary cortisol concentrations compared with fenceline sows, although they were only numerically greater than those for control sows. During phase 2, removing the boar did not increase fighting among sows or affect shoulder scratches or salivary cortisol concentrations. The presence of a boar was minimally effective at reducing fighting and scratches during the postmixing period, and sows showed a greater stress response in the presence of a boar.

Measuring emotional processes in animals: the utility of a cognitive approach

Contemporary researchers regard emotional states as multifaceted, comprising physiological, behavioural, cognitive and subjective components. Subjective, conscious experience of emotion can be inferred from linguistic report in humans, but is inaccessible to direct measurement in non-human animals. However, measurement of other components of emotion is possible, and a variety of methods exist for monitoring emotional processes in animals by measuring behavioural and physiological changes. These are important tools, but they have limitations including difficulties of interpretation and the likelihood that many may be sensitive indicators of emotional arousal but not valence-pleasantness/unpleasantness. Cognitive components of emotion are a largely unexplored source of information about animal emotions, despite the fact that cognition-emotion links have been extensively researched in human cognitive science indicating that cognitive processes-appraisals of stimuli, events and situations-play an important role in the generation of emotional states, and that emotional states influence cognitive functioning by inducing attentional, memory and judgement biases. Building on this research, it is possible to design non-linguistic cognitive measures of animal emotion that may be especially informative in offering new methods for assessing emotional valence (positive as well as negative), discriminating same-valenced emotion of different types, identifying phenotypes with a cognitive predisposition to develop affective disorders, and perhaps shedding light on the issue of conscious emotional experiences in animals.

The effects of ractopamine on the behavior and physiology of finishing pigs

The objectives of this study were to examine the effects of ractopamine (RAC) on the behavior and physiology of pigs during handling and transport. Twenty-four groups of three gilts were randomly assigned to one of two treatments 4 wk before slaughter: finishing feed plus RAC (10 ppm) or finishing feed alone. Pigs were housed in the same building in adjacent pens with fully slatted floors and ad libitum access to feed and water. Behavioral time budgets were determined in six pens per treatment over a single 24-h period during each week. Behavioral responses of these pigs to routine handling and weighing were determined at the start of the trial and at the end of each week. Heart-rate responses to unfamiliar human presence were measured in all pigs and blood samples were taken from a single pig in each pen on different days during wk 4. At the end of wk 4, all pigs were transported for 22 min to processing. Heart rate was recorded from at least one pig per pen during transport and a postmortem blood sample was taken from those pigs that were previously sampled. During wk 1 and 2, RAC pigs spent more time active (P < 0.05), more time alert (P < 0.05), and less time lying in lateral recumbency (P < 0.05). They also spent more time at the feeder in wk 1 (P < 0.05). At the start of the trial, there were no differences in behavioral responses to handling. However, over each of the next 4 wk, fewer RAC pigs exited the home pen voluntarily, they took longer to remove from the home pen, longer to handle into the weighing scale and needed more pats, slaps, and pushes from the handler to enter the scales. At the end of wk 4, RAC pigs had higher heart rates in the presence of an unfamiliar human (P < 0.05) and during transport (P < 0.05), but not during loading and unloading. Also at the end of wk 4, RAC pigs had higher circulating catecholamine concentrations (P < 0.05) than control pigs. Circulating cortisol concentrations and cortisol responses to transport did not differ between treatments. The results show that ractopamine affected behavior, heart rate, and catecholamine profile of finishing pigs and made them more difficult to handle and potentially more susceptible to handling and transport stress.

Sexual motivation in relation to social rank in pair-housed sows

The influence of social subordination on sexual motivation during oestrus was studied using 36 sows of which 24 treatment sows were housed in pairs and 12 control sows were housed individually in 12 and 6 m(2) pens, respectively. Video recordings were made from 07:00 h to 19:00 h during the first 2 days after grouping, which took place 3 days after weaning of the piglets. Based on the aggressive interactions between the pair-housed sows, their rank was determined. From day 4 after weaning, a test for sexual proceptive behaviour was carried out twice daily and back-pressure test was carried out four times daily in order to detect standing oestrus. When standing oestrus had occurred, transrectal ultrasonographical scans were also carried out in order to determine if ovulation took place. The proceptivity test took place in a T-maze with a 2 m x 10 m runway ending in two 1.5 m x 1.5 m goal boxes each adjacent to a stimulus compartment. One compartment contained an adult sexually experienced boar and the other was empty. Latency to and duration of time spent close to the boar and time spent presenting were recorded during the 10-min test period. On the first day that standing oestrus had been detected, a test for sexual receptivity was also carried out by introducing the sow to a mature boar in his home pen (9 m(2)). Sexual- and fear-related behaviour of sow and boar were recorded until mating was terminated or the sow had spent 5 min in the pen without mating being initiated. During oestrus the proceptivity test showed a significant increase (P < 0.05) in the time spent standing close to the boar and in presenting for single-housed sows and for pair-housed dominant sows, but not for subordinate sows. During oestrus subordinate sows spent significantly less time standing close to the boar than the dominant sows (P = 0.01) and the same tended to be the case for presenting (P = 0.07). In the receptivity test more subordinate sows than dominant sows fled (40% versus 0%, P = 0.001) and more subordinate sows than dominant sows squealed (58% versus 15%, P = 0.02) as a response to boar stimulation. In both tests, the single-housed sows differed neither from the dominant nor the subordinate sows. There was however no difference between the groups in the weaning to oestrous interval, duration of oestrus and number of piglet born. In addition, all the sows ovulated. The results indicate that social subordination can have significant consequences for sexual motivation in sows. Subordinate sows showed fear-related behaviour in response to boar stimulation even when they were in standing oestrus. Thus, both heat detection and mating may be impaired in subordinate sows. The results emphasise the importance to alleviate the social stress experienced by subordinates as well as the need for stock people to pay special attention to these animals when they are to be mated or inseminated.

Vocalisations of the adult female domestic pig during a standard human approach test and their relationships with behavioural and heart rate measures

Vocal communication in the domestic pig is generally not well documented. The aim of this experiment was to categorise and ascribe the function of the vocalisations of 67 Large WhitexLandrace gilts during a standard human approach test. At testing, each group of 3-5 gilts was moved to a handling area where each individual in turn was fitted with a heart rate monitor and introduced individually to a 2.4mx2.4m test arena. After 2min familiarisation, an unfamiliar human entered the pen and stood for 3min against one wall. Behaviour and sound were recorded continuously with sound recordings transferred onto computer for analysis. Three categories of calls were initially identified: single grunts, single squeals and rapidly repeated grunts. Sixty-six gilts performed single grunts, whereas only 28 and 16 gilts performed the other two categories, respectively. Single grunts could be sub-divided into two types based on sound amplitude profile. These types differed significantly in duration. Gilts performed more short and long grunts per minute during the 3min test period than during the familiarisation period. Most short grunts observed in a subset of 15 gilts were performed with the snout close to a pen surface or the human. The rate of short grunts during the test period was negatively correlated with the time taken to make contact with the human and positively correlated with the amount of locomotor behaviour carried out, the total number of interactions with the human and the total time spent within 0.5m of the human. Most long grunts observed in a subset of 15 gilts were performed with the snout away from any surface. The rate of long grunts during the test period positively correlated with amount of locomotor behaviour and heart rate, after the effect of activity had been removed. Squeals could similarly be sub-divided into long and short types on the basis of amplitude profile. Gilts that squealed carried out more locomotor behaviour, interacted with the human more, had higher mean heart rates and lower heart rate rise when touched by the human, suggesting a higher degree of arousal. Rapidly-repeated grunts were associated with close human interaction. The results indicate that the domestic pig performs a number of distinct vocalisations during isolation. Short single grunts appear to be associated with investigatory behaviour. Long single grunts may be a form of contact call, the rate of which is related to physiological and behavioural activity. Squeals may have similar function but result from a higher level of arousal. Short, rapidly-repeated grunts appear to have either a greeting or threat function. With further research, certain pig vocalisations may be identified as providing useful additional information about an individual's welfare.

Behavioural and physiological consequences of acute social defeat in growing gilts: effects of the social environment

Endocrine, behavioural and immunologic processes, together with body growth, were evaluated in gilts that were defeated at 10 weeks of age in resident-intruder tests. Immediately after defeat, gilts were either separated from or reunited with a familiar conspecific (litter-mate; always a barrow). Gilts were assigned to one of four treatments: (a) DI: defeat, followed by isolation (separation from original litter-mate; n=8); (b) I: no defeat, isolation (control group; n=9); (c) DP; defeat, followed by pair-housing (reunion with original litter-mate; n=8); and (d) P: no defeat, pair-housing (control group; n=8). The following general conclusions were derived: (1) social defeat caused pronounced short-term elevations in hypothalamic-pituitary-adrenal (HPA) and sympathetic-adrenal medullary activities, and of prolactin levels. Moreover, as soon as 1h after defeat, percentages of blood lymphocytes and neutrophilic granulocytes were, respectively, decreased and increased; (2) social defeat had some long-lasting influence on behaviour and physiology, but isolation predominantly determined responses in the longer term. Defeat, as well as isolation, resulted in increased cardiovascular activities compared to P controls, as observed in a novel object test (NOT: +7 days) and an aversion test (AVT: +14 days). Moreover, defeated as well as isolated gilts did not habituate to a repeated novel environment test (NET: -7, +2 and +7 days) in terms of frequencies of vocalising, whereas P controls did. Isolation, through the separation from any other pig, was responsible for the other observed long-term characteristics, which developed progressively. Isolated gilts showed high mobilities and high cortisol responses in the repeated NET (+7 days), not being habituated. This contrasted the reactions of pair-housed gilts, which were much reduced. In addition to their high cardiovascular activities in the NOT and the AVT, isolated gilts also displayed higher heart rates in the repeated NET and during human presence following the NOT, compared to pair-housed gilts. Finally, isolated gilts were more inhibited to approach a novel object (in the NOT) than pair-housed pigs; and (3) stress responses of defeated gilts were modulated by the subsequent social environment. Stimulation of the HPA-axis (plasma- and salivary cortisol) was prolonged in those defeated gilts which were isolated (observed in the first hour). Changes in leucocyte subsets were still observed after 3 days in DI, but were 'normalised' within 1 day in DP gilts. Two days after defeat, habituation to the repeated NET in terms of mobility and salivary cortisol responses occurred in control and DP gilts, but not in DI gilts. We argue that these effects of the social environment shortly after defeat were related to a stress-reducing effect of a stable social relationship, i.e. social support.

A noninvasive radiotelemetry system to monitor heart rate for assessing stress responses of bovines

A noninvasive radiotelemetry system was developed to monitor heart rates of cows and to view and analyze data. The system was validated by comparing heart rate data of two restrained heifers collected simultaneously using telemetric and direct electrocardiogram measurements and by acquiring data over 72 h from two dry cows housed in an experimental handling facility consisting of a free-stall pen, a holding pen, a pass-through stall, and a second holding pen. Telemetric and direct measurements in response to pharmacological elevation of heart rates were essentially identical. For cows in the experimental facility, peristimulus-time histograms indexed to standing or lying showed that average heart rates for cows increased 4.0 +/- 1.4 beats/min after cows stood and decreased 4.8 +/- 1.0 beats/min after cows lay. Similarly, the average heart rate for the cow naive to the facility increased from 60 to 86 beats/min and remained elevated for 6.3 min when heart rate was indexed to maximal heart rate within +/- 3 min of entry into the pass-through stall. Heart rate for the naive cow increased consistently from around 60 to over 160 beats/min during repeated agonistic encounters between animals. Heart rate for the other cow was not affected by the encounters. These results show clearly that heart rate can be used to monitor animal anxiety.