Subordination style’ in pigs? The response of pregnant sows to mixing stress affects their offspring’s behaviour and stress reactivity

Posted in: Production, Welfare by admin on July 25, 2011 | No Comments

In various mammals stress during gestation can result in long term effects on the behaviour and physiology of the offspring. The aims of this study were to characterize individual variation among gilts in their behavioural and physiological response to a commercially relevant social challenge (mixing with older sows) during gestation and to determine whether this variation was associated with a corresponding variation in the subsequent effects on the offspring. After assessing dominance in a food competition test, 24 gilts were studied in groups of six during two one-week periods (unmixed – U). These gilts were split into eight subgroups of three gilts, each of which were mixed with two older sows for one week (mixed – M1) before being returned to their original group of six for two weeks. Mixing was then repeated using different older sows during a second week (mixed – M2). Aggressive behaviour, skin lesions and salivary cortisol increase over baseline were higher, and weight gain was lower during mixed periods. During mixing gilts spent more time in feeder stalls, avoiding sows lying in a straw-bedded area, although there was considerable variation among individuals in the extent to which they interacted with or avoided sows. Gilts which interacted more with sows had lower weight gain and higher lesion scores. Previously dominant gilts had higher salivary cortisol increases during mixing. Measures of the impact of mixing, most notably M1 lesion scores, were associated with the behaviour of their offspring: gilts with more lesions had piglets that were less active and less vocal on the day of weaning and over 31 days post-weaning, and were less aggressive over 31 days post-weaning. Thirty-two piglets (from 16 of the gilts) were either restrained for 30 min or not restrained prior to euthanasia at 60 days of age. The restrained piglets from gilts with higher M1 lesion scores had higher levels of corticotropin-releasing hormone mRNA in the paraventricular nucleus and amygdala. This study demonstrates that differences between individual gilts in their experience of a stressful social challenge co-vary with the extent to which this pre-natal stress impacts on their offspring.

For more information the full article can be found at http://journals.elsevierhealth.com/periodicals/applan/issues

A flooring comparison: The impact of rubber mats on the health, behavior, and welfare of group-housed sows at breeding

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Comfortable flooring may impact many aspects of an animal’s welfare, including lying behavior, an animal’s ability to change postures, and incidence of lameness and lesions. Therefore, we hypothesized that the addition of rubber mats to stalls of group pens would improve sow health, comfort and welfare during breeding. In this study, Landrace X York-Yorkshire sows (128) were mixed post-weaning and housed in pens of four. The pens contained a slatted group area and four feeding stalls. Rubber mats (measuring 1.83m X 0.61m X 1.27 cm) were added to the feeding stalls of half of the pens and rotated to the opposite pens for each replication. The behavioral time budgets of the sows were recorded throughout the experiment; lesion and lameness scores were collected prior to mixing and at the end of the experiment. Data were analyzed as repeated measures mixed models with post hoc Tukey tests. The pattern of behaviors performed in the stall versus group area was different for mat and concrete treatments. Tukey tests revealed that only resting behaviors were affected. We then examined resting behavior in detail. Time spent in different resting postures (sternal versus lateral lying) differed between treatments, where sows on mats spent more time lying laterally and performed more of their lying behavior in the stalls compared to sows on concrete. Additionally, sows stood up and laid down more frequently than sows on concrete. Warm temperatures reduced resting behavior in the stalls. Sows in matted pens had a lower total lesion score at the end of the experiment in comparison to sows in concrete pens. Lameness scores did not differ between treatments. These results imply that the provision of alternative comfort flooring may provide welfare benefits to breeding sows, though environmental temperature needs to be considered when providing rubber mats.

Sow preferences for farrowing under a cover with and without access to straw

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In semi-natural environments sows often select a protected nest site at farrowing. Investigations of nest site selection under indoor conditions are scarce but suggest that sows prefer to nest and farrow under a covered area. Since feed-back from a functional nest may improve maternal behaviour and thus piglet survival we investigated if access to a covered area and ad libitum access to straw would improve maternal behaviour of importance for piglet survival. We used forty-four sows, first time mothers-to-be, housed in large individual pens from approximately 2 weeks prior to expected parturition. The sows were randomly distributed to four treatment groups of +/− ad libitum access to straw combined with +/− access to a covered area in the pen. The sows’ position in the pen (left or right side) was observed from 24 h prior to birth of the first piglet until 24 h after using 10-min interval scan sampling and the temporal pattern of sow position in relation to position of the cover (left or right side of the pen) was studied. Furthermore, postural and nest-building behaviours were observed, as well as situations where the piglets were either at risk of being crushed or were crushed. The results showed no significant influence of cover on sow position. Odds-ratio for choosing the covered farrowing position was 1.4 (95% creditability interval (0.4–5.1)). The temporal pattern of sow position showed that the probability of observing the sows in the part of the pen classified as the farrowing position increased from close to 0.5 to 1 as parturition approached and stayed high during the 24 h observation period after birth of the first piglet, except for a small drop around 12 h after birth of the first piglet. However, the tendency to stay in the nest during farrowing was not increased neither by cover nor by ad libitum access to straw. Access to cover significantly increased prepartum nest-building behaviour whereas there was no significant influence of access to straw. However, it should be taken into account that all sows had access to sawdust on the floor, which may also serve as a nesting material.

The number of crushing and near crushing situations within 24 h after birth of first piglet was significantly decreased in pens with access to straw whereas there was no significant influence of cover on this variable. Neither the number of scan intervals with lateral lying nor the number of postural changes were significantly influenced by cover or straw. In conclusion, the sows did select a specific nest site within the farrowing pen, but neither the choice of nest site nor the temporal consistency of staying in the nest were significantly affected by cover or ad libitum access to straw. Access to a covered area increased the occurrence of nest-building behaviour whereas access to straw reduced the number of near crushing situations.

For more information the full article can be found at http://journals.elsevierhealth.com/periodicals/applan/issues

The behaviour of male fattening pigs following either surgical castration or vaccination with a GnRF vaccine

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Vaccination of male fattening pigs with a gonadotropin releasing factor (GnRF) vaccine is regarded as a possible solution to solve the welfare problem associated with surgical castration, which causes pain and stress even when performed under local or general anaesthesia. The objective of the present study was to compare the behaviour of male fattening pigs either surgically castrated without anaesthesia (C) or vaccinated twice with a GnRF vaccine (V). Data collection took place in a commercial German fattening unit. Each treatment comprised 8 groups of 12 pigs, housed in fattening pens with partially slatted floor and liquid feed provided three times a day. Data on postures were scored from 24-h videos recorded in every week of the fattening period (16 weeks) using scan sampling with 5 min intervals. Social behaviour was analysed in weeks 2, 4, 6, 8, 10, 12, 14, 15 and 16 by continuous behaviour recording of focus animals in four blocks of 2 h phased evenly during the day. Overall, during the whole fattening period, vaccinates (V) were more active than surgical castrates (C), indicated by a higher proportion of pigs standing (C:9.3%; V:10.74%). ‘V’ animals showed a significant decrease in standing and an increase of sitting and lying after the second vaccination of Improvac. No significant effects of treatment on the total number of agonistic interactions and on biting and fighting were found. In ‘V’ the prevalence of aggressive behaviours decreased after the second vaccination which was not found in ‘C’ during the same period. ‘V’ animals showed a higher level of mounting behaviour compared with ‘C’ animals, but on a very low level. Treatment had no effect on the prevalence of play behaviour and manipulating of pen mates. It is concluded that housing of male pigs vaccinated against GnRF in single sex groups of 12 individuals does not increase behavioural problems in the fattening period compared with surgically castrated males.

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Ethology applied to animal ethics

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According to modern animal welfare legislation, animals should be protected from suffering and lasting harm not for the benefit of us humans as in earlier anthropocentric conceptions, but in their own interest. The driving force behind animal protection is our empathy with animals which triggers feelings of compassion. Empathy with animals most likely is a psychological side-effect of adaptive empathy among humans, and its expression is largely determined by the degree of similarity between animals and us in morphology and behaviour. As a result, compassion with animals is vulnerable to anthropocentric bias, prejudice, and deception, and animal protection based on compassion is likely to be unfair towards animals. Moreover, from an ethological perspective, protecting animals in their own interest represents true altruism which places considerable ethical demand on us. However, there may be hidden selfish intentions that question the altruistic nature of animal protection, while at the same time facilitating its implementation. For example, animal protection could help to avoid unpleasant feelings induced by witnessing cruel actions towards animals. Alternatively, exhibiting a caring personality towards animals could represent human social behaviour that pays off indirectly through building up a caring reputation. It is, therefore, important to distinguish between our intention to protect animals (which may be partly selfish) and true animal protection that needs to be justified biologically by values that apply to the animals. Based on the sentientist nature of animal welfare legislation, the greatest challenges to applied ethologists, and important ones as testified by this special issue, are to determine sentience in animals and to establish valid and reliable measures of affective states such as suffering and well-being. Moreover, the integrity concept would relieve scientists from solving the ‘hard problem’ of animal consciousness first, or from establishing valid measures of demand or aversion that are notoriously difficult to establish. In particular, measures of behavioural integrity could offer an opportunity for applied ethology to strengthen its impact on ethical and legal decision-taking, thereby advancing animal welfare without compromising scientific credibility.

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Investigations on genetic disease resistance in swine—A contribution to the reduction of pain, suffering and damage in farm animals

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This review deals with genetic disease resistance in pigs as a prospective opportunity to reduce pain, suffering and damage in swine production. Even under favourable terms of housing and management, infectious diseases are wide-spread, and have to be ranked among the major sources for suffering in international pig production. There is abundant variability in resistance/susceptibility of pig populations and breeds to a number of pathogens, including several viruses, bacteria, and parasites, even at similar performance levels. Practical applications of disease resistance in farm animals and established knowledge on disease resistance in swine are presented. The difficulty lies in the identification of carriers of favourable gene variants. With tools and technologies developed in the context of genome projects, new opportunities to dissect the genetic control of host response to infection are presented with QTL analysis of Sarcocystis miescheriana resistance given as an exemplary parasite model: this model demonstrates the existence of outstanding gene loci and their role for polygenic trait variability. It further provides evidence for common mechanisms involved in resistance to different pathogens. Although a long way from the model to markers for disease resistance, pain, suffering, and damage might be reduced by the applications of genetic disease resistance in pig production in the future.

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The effect of sampling strategy on the estimated prevalence of welfare outcome measures on finishing pig farms

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The effect of sampling strategy on the estimates of prevalence of some welfare outcome measures was investigated as part of a larger project examining the feasibility and benefits of incorporating some on-farm welfare outcome assessments into UK Pig Farm Assurance Schemes. All finishing pigs (>40 kg) on 6 farms that had pens of 25 pigs or less were assessed for dirtiness, body lesions, tail lesions, bursae, lameness, oral behaviour and pigs requiring hospitalisation. A statistical sampling methodology was applied to the data to generate 10,000 random samples for each measure, on each farm and for every possible number of sampled pens on that farm. The 95% confidence interval range, the proportion of samples outside a ‘tolerance’ range and the proportion of samples that would wrongly classify the farm with respect to a ‘threshold’ were calculated for each measure on each farm for every possible sample size. It was found that even large sample sizes were unable to accurately reflect the whole farm for measures with very low prevalences (lameness and pigs requiring hospitalisation). For the other measures, as the number of pens sampled increased, the confidence interval range and the proportion of samples outside the ‘tolerance’ range reduced. The differing inter-pen variation in prevalence on a farm gave rise to differences in accuracy of prevalence estimates between the farms. Those farms with a true farm prevalence close to the threshold required more pens to be sampled to achieve the same level of accuracy of classification as other farms with similar confidence intervals but a more extreme prevalence. The effect of sampling on the estimate of prevalence should be considered when an accurate prevalence of the whole population is required.

For more information the full article can be found at http://journals.elsevierhealth.com/periodicals/applan/issues

Interdependence of welfare outcome measures and potential confounding factors on finishing pig farms

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The factors influencing the observed prevalence of some welfare outcome measures were investigated as part of a larger project examining the feasibility and benefits of incorporating on-farm welfare outcome assessments into UK Pig Farm Assurance Schemes. All finishing pigs (>40 kg) on six farms that had pens containing 25 pigs or less were assessed for dirtiness, body lesions, tail lesions, bursitis, lameness, oral behaviour and pigs requiring hospitalisation. The overall small number of significant correlations between the measures across all farms (29 out of a possible 120) and the lack of a significant correlation between any pair of measures on all six or even five farms suggests that no measure can be reliably replaced by another. On the three farms with the highest farm prevalence of dirtiness there were significant negative correlations between pen prevalences of dirtiness and recorded tail and/or body lesions. The prevalence of pigs requiring hospitalisation was positively correlated with lameness on four farms and tail lesions on three farms. Using a univariate general linear model the time of observation was only found to correlate with one measure, the dirtiness of the pigs, with the prevalence of dirtiness in pens on the three ‘dirtiest’ farms increasing as the day progressed. There was no effect of the stocking density, group size, time since feeding and time since straw provision on the prevalence of any of the outcome measures. It is recommended that to prevent bias in the recording of tail and body lesions farm assurance assessments are conducted on pigs with a prevalence for dirtiness of less than 17%. Lower prevalences of dirtiness are more likely to occur on some farms first thing in the morning.

For more information the full article can be found at http://journals.elsevierhealth.com/periodicals/applan/issues

Effects of exposing pigs to moving and odors in a simulated slaughter chute

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Pigs in the finishing stage are infrequently handled and can be difficult to handle when experiencing novel situations. This study sought to determine the effects of minimal training and a novel odor/taste reward on the ease of handling finishing pigs in a novel environment. Pigs were assigned to one of four treatments organized in a factorial arrangement: training and odor exposure at the barn or not (trained or non-trained, respectively) and provision or not of maple syrup in the simulated pre-stun area of a slaughter plant (reward or no reward, respectively). 14 pens of trained pigs were let out of their home pens and onto a trailer for 10 min/day for 10 days and could chew on maple syrup soaked flags. 14 pens of non-trained pigs were not handled or exposed to maple syrup. After the 10 days, trained and non-trained pigs were transported, unloaded and then experienced a novel simulated pre-stun area. A maple syrup-soaked flag (reward) was dragged through the simulated pre-stun area and put in a simulated CO₂ stun box. Nonrewarded pigs were not exposed to maple syrup. Trained pigs unloaded the trailer and reached the resting pen faster than non-trained pigs. Trained pigs had fewer blood neutrophils and more lymphocytes than non-trained pigs. Rewarded pigs received fewer taps before reaching the simulated CO₂ stun box than non-rewarded pigs. Cortisol concentration increased when the total time to reach the simulated CO₂ stun box increased. Pigs that were allowed to exercise out of their home pen and were given access to an odor/taste reward moved faster and the neutrophil:lymphocyte ratio was decreased when exposed to a novel environment containing the same odor/taste reward.

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Measuring cutaneous thermal nociception in group-housed pigs using laser technique—Effects of laser power output

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Nociceptive testing (the testing to evaluate the perception of pain) is a valuable tool in the development of pharmaceutical products, for basic nociceptive research, and for studying changes in pain sensitivity is investigated after inflammatory states or nerve injury. However, in pigs only very limited knowledge about nociceptive processes are available, especially methodology which is applicable for pigs kept in group-housing without disturbing the daily routines of the animals. To validate a laser-based method to measure thermal nociception in group-housed pigs, we performed two experiments observing the behavioural responses toward cutaneous nociceptive stimulation from a computer-controlled CO2-laser beam applied to either the caudal part of the metatarsus on the hind legs or the shoulder region of gilts. In Exp. 1, effects of laser power output on nociceptive responses toward stimulation on the caudal aspects of the metatarsus were examined using 15 gilts kept in one group and tested in individual feeding stalls after feeding. Increasing the power output led to gradually decreasing latency to respond and affected the types of responding (less non-responding, less moving leg, less lifting leg, and more kicking). Furthermore, the occurrence of tail flicking during laser stimulation was increased. In Exp. 2, effects of laser power output on nociceptive responses toward stimulation on the shoulder region were examined in 10 gilts kept under the same conditions. Again, increasing the power output led to gradually decreasing latency to respond and affected the types of responding (less non-responding, less moving shoulder, less moving body, higher occurrence of muscle twitch, and higher occurrence of rubbing shoulder). In conclusion, the results of the two experiments suggest that behavioural responses to nociceptive cutaneous laser stimulation are a valid measure of nociception in grouphoused gilts which are tested with a minimal disturbance of daily routines, and both when applied to the hind legs and to the shoulder region. Furthermore, pig nociceptive responses appear to be graded, to include new types of behaviour as the nociceptive input increases and to show elements of site-specificity.

For more information the full article can be found at http://journals.elsevierhealth.com/periodicals/applan/issues