Enrichment use in finishing pigs and its relationship with damaging behaviours: Comparing three wood species and a rubber floor toy

Environmental enrichment in pig housing is a legal requirement under current EU legislation, but some recommended loose materials may cause obstructions in fully-slatted systems. Wood is an organic material that could be compatible with slatted systems. This study investigated enrichment use in finishing pigs (three wood species and a rubber floor toy) and explored the relationship between use and damaging behaviours, and physiological and physical measures of stress and injury. Individual variation in enrichment use within pen was also investigated. Pigs (12 weeks old; week 0) were housed in 40 pens of seven pigs (n = 280). One of four different enrichment items (one spruce, larch, or beech wooden post, or rubber floor toy) was randomly assigned to each pen (10 pens/treatment). The behaviour of each individually marked pig was observed continuously from video recordings taken on six different occasions (twice during week 2, 4 and 7; 1 h per occasion). Individual tail/ear lesion and tear staining scores were recorded every 2 weeks. Saliva samples for cortisol analysis were obtained from three focal pigs per pen every 2 weeks. These focal pigs were selected based on the latency to approach the experimenter on the first sampling day and classified as ‘Approach’, ‘Neutral’ or ‘Avoid’. Carcasses were inspected for tail lesions and potential oral damage. Time spent using enrichment was higher in pigs with spruce and rubber toy than with larch and beech (P < 0.001). Spruce was used up the most quickly and was the softest of the wood species (P < 0.001). High use of spruce was not due to consistent high use by certain pigs. No treatment effect on any other behaviour was recorded, but enrichment use was positively correlated with damaging behaviours at pen level (P < 0.001). Spruce pigs had slightly more severe tail lesion scores than Beech (P < 0.05). Salivary cortisol did not differ between treatments but was higher in ‘Avoid’ than ‘Approach’ pigs (P = 0.04). No clear oral damage that could be attributed to using wood was found. By investigating enrichment use at both pen and individual level, a more complete picture was obtained of how pigs used the enrichment. Wood appears to be a safe material to use as environmental enrichment for pigs and a softer wood species was preferred by pigs with equal preference for the rubber floor toy.Department of Agriculture, Food and the Marine in Irelan

Automatic early warning of tail biting in pigs:3D cameras can detect lowered tail posture before an outbreak

<div><p>Tail biting is a major welfare and economic problem for indoor pig producers worldwide. Low tail posture is an early warning sign which could reduce tail biting unpredictability. Taking a precision livestock farming approach, we used Time-of-flight 3D cameras, processing data with machine vision algorithms, to automate the measurement of pig tail posture. Validation of the 3D algorithm found an accuracy of 73.9% at detecting low vs. not low tails (Sensitivity 88.4%, Specificity 66.8%). Twenty-three groups of 29 pigs per group were reared with intact (not docked) tails under typical commercial conditions over 8 batches. 15 groups had tail biting outbreaks, following which enrichment was added to pens and biters and/or victims were removed and treated. 3D data from outbreak groups showed the proportion of low tail detections increased pre-outbreak and declined post-outbreak. Pre-outbreak, the increase in low tails occurred at an increasing rate over time, and the proportion of low tails was higher one week pre-outbreak (-1) than 2 weeks pre-outbreak (-2). Within each batch, an outbreak and a non-outbreak control group were identified. Outbreak groups had more 3D low tail detections in weeks -1, +1 and +2 than their matched controls. Comparing 3D tail posture and tail injury scoring data, a greater proportion of low tails was associated with more injured pigs. Low tails might indicate more than just tail biting as tail posture varied between groups and over time and the proportion of low tails increased when pigs were moved to a new pen. Our findings demonstrate the potential for a 3D machine vision system to automate tail posture detection and provide early warning of tail biting on farm.</p></div

Association of HPA axis-related genetic variation with stress reactivity and aggressive behaviour in pigs

<p>Abstract</p> <p>Background</p> <p>Stress, elicited for example by aggressive interactions, has negative effects on various biological functions including immune defence, reproduction, growth, and, in livestock, on product quality. Stress response and aggressiveness are mutually interrelated and show large interindividual variation, partly attributable to genetic factors. In the pig little is known about the molecular-genetic background of the variation in stress responsiveness and aggressiveness. To identify candidate genes we analyzed association of DNA markers in each of ten genes (<it>CRH </it>g.233C>T, <it>CRHR1 </it>c.*866_867insA, <it>CRHBP </it>c.51G>A, <it>POMC </it>c.293_298del, <it>MC2R </it>c.306T>G, <it>NR3C1 </it>c.*2122A>G, <it>AVP </it>c.207A>G, <it>AVPR1B </it>c.1084A>G, <it>UCN </it>g.1329T>C, <it>CRHR2 </it>c.*13T>C) related to the hypothalamic-pituitary-adrenocortical (HPA) axis, one of the main stress-response systems, with various stress- and aggression-related parameters at slaughter. These parameters were: physiological measures of the stress response (plasma concentrations of cortisol, creatine kinase, glucose, and lactate), adrenal weight (which is a parameter reflecting activity of the central branch of the HPA axis over time) and aggressive behaviour (measured by means of lesion scoring) in the context of psychosocial stress of mixing individuals with different aggressive temperament.</p> <p>Results</p> <p>The SNP <it>NR3C1 </it>c.*2122A>G showed association with cortisol concentration (p = 0.024), adrenal weight (p = 0.003) and aggressive behaviour (front lesion score, p = 0.012; total lesion score p = 0.045). The SNP <it>AVPR1B </it>c.1084A>G showed a highly significant association with aggressive behaviour (middle lesion score, p = 0.007; total lesion score p = 0.003). The SNP <it>UCN </it>g.1329T>C showed association with adrenal weight (p = 0.019) and aggressive behaviour (front lesion score, p = 0.029). The SNP <it>CRH </it>g.233C>T showed a significant association with glucose concentration (p = 0.002), and the polymorphisms <it>POMC </it>c.293_298del and <it>MC2R </it>c.306T>G with adrenal weight (p = 0.027 and p < 0.0001 respectively).</p> <p>Conclusions</p> <p>The multiple and consistent associations shown by SNP in <it>NR3C1 </it>and <it>AVPR1B </it>provide convincing evidence for genuine effects of their DNA sequence variation on stress responsiveness and aggressive behaviour. Identification of the causal functional molecular polymorphisms would not only provide markers useful for pig breeding but also insight into the molecular bases of the stress response and aggressive behaviour in general.</p

Food restriction reduces neurogenesis in the avian hippocampal formation

The mammalian hippocampus is particularly vulnerable to chronic stress. Adult neurogenesis in the dentate gyrus is suppressed by chronic stress and by administration of glucocorticoid hormones. Post-natal and adult neurogenesis are present in the avian hippocampal formation as well, but much less is known about its sensitivity to chronic stressors. In this study, we investigate this question in a commercial bird model: the broiler breeder chicken. Commercial broiler breeders are food restricted during development to manipulate their growth curve and to avoid negative health outcomes, including obesity and poor reproductive performance. Beyond knowing that these chickens are healthier than fully-fed birds and that they have a high motivation to eat, little is known about how food restriction impacts the animals' physiology. Chickens were kept on a commercial food-restricted diet during the first 12 weeks of life, or released from this restriction by feeding them ad libitum from weeks 7-12 of life. To test the hypothesis that chronic food restriction decreases the production of new neurons (neurogenesis) in the hippocampal formation, the cell proliferation marker bromodeoxyuridine was injected one week prior to tissue collection. Corticosterone levels in blood plasma were elevated during food restriction, even though molecular markers of hypothalamic-pituitary-adrenal axis activation did not differ between the treatments. The density of new hippocampal neurons was significantly reduced in the food-restricted condition, as compared to chickens fed ad libitum, similar to findings in rats at a similar developmental stage. Food restriction did not affect hippocampal volume or the total number of neurons. These findings indicate that in birds, like in mammals, reduction in hippocampal neurogenesis is associated with chronically elevated corticosterone levels, and therefore potentially with chronic stress in general. This finding is consistent with the hypothesis that the response to stressors in the avian hippocampal formation is homologous to that of the mammalian hippocampus

Sex differences, or not, in spatial cognition in albino rats: acute stress is the key

Male rats, Rattus norvegicus, typically outperform females in tests of spatial cognition. However, as stress affects cognition differently in the two sexes, performance differences may be an artefact of stress. Rats face at least two sources of stress during an experiment: the test situation (acute) and housing conditions (chronic, e. g. isolation). We used a task (the Morris water maze, MWM) that allowed testing of both spatial working and reference memory to investigate whether chronic stress (isolation housing) and/or acute stress (the task) has a differential impact on spatial cognition in male and female albino rats. Irrespective of age at the onset of isolation housing, isolated rats were not spatially impaired relative to pair-housed rats. However, the acute stress of the task led to adult males apparently outperforming adult females: adult females took longer to reach the platform than did males because they spent more time in thigmotaxis (swimming close to the wall) during testing. In juvenile rats, the stress caused by swimming in the MWM resulted in both males and females being highly thigmotactic and no sex difference in performance. We conclude that stress can lead to apparent differences between the sexes in performance on a spatial cognition task. (C) 2008 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.</p

Sex differences, or not, in spatial cognition in albino rats: acute stress is the key

Male rats, Rattus norvegicus, typically outperform females in tests of spatial cognition. However, as stress affects cognition differently in the two sexes, performance differences may be an artefact of stress. Rats face at least two sources of stress during an experiment: the test situation (acute) and housing conditions (chronic, e. g. isolation). We used a task (the Morris water maze, MWM) that allowed testing of both spatial working and reference memory to investigate whether chronic stress (isolation housing) and/or acute stress (the task) has a differential impact on spatial cognition in male and female albino rats. Irrespective of age at the onset of isolation housing, isolated rats were not spatially impaired relative to pair-housed rats. However, the acute stress of the task led to adult males apparently outperforming adult females: adult females took longer to reach the platform than did males because they spent more time in thigmotaxis (swimming close to the wall) during testing. In juvenile rats, the stress caused by swimming in the MWM resulted in both males and females being highly thigmotactic and no sex difference in performance. We conclude that stress can lead to apparent differences between the sexes in performance on a spatial cognition task. (C) 2008 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.</p

Sex differences in spatial cognition are not caused by isolation housing

In mammals, males typically have better spatial ability than do females. However, most of the data come from laboratory tests and it is possible that factors impacting on the captive animal cause the observed sex differences in spatial cognition. A common influence on cognitive ability is stress, which may have its effect acutely, in the testing situation, or chronically, due to the housing conditions. We used a spatial working and reference memory task (the Morris water maze) to investigate if isolation housing had a differential impact on spatial cognition in male and female rats. Either as juveniles or as adults, rats were housed in pairs or in isolation. We also manipulated the duration of isolation housing. Regardless of housing condition, we found a sex difference in spatial ability only in the youngest rats. However, we found no evidence that isolated rats were spatially impaired relative to pair-housed rats. We also found no difference in body weight, food intake or bar biting behaviour (indicators of welfare in rodents) between pair and isolated rats. We conclude that isolation housing causes insufficient stress to cause sex differences in spatial cognition.</p

Sex differences in spatial cognition are not caused by isolation housing

In mammals, males typically have better spatial ability than do females. However, most of the data come from laboratory tests and it is possible that factors impacting on the captive animal cause the observed sex differences in spatial cognition. A common influence on cognitive ability is stress, which may have its effect acutely, in the testing situation, or chronically, due to the housing conditions. We used a spatial working and reference memory task (the Morris water maze) to investigate if isolation housing had a differential impact on spatial cognition in male and female rats. Either as juveniles or as adults, rats were housed in pairs or in isolation. We also manipulated the duration of isolation housing. Regardless of housing condition, we found a sex difference in spatial ability only in the youngest rats. However, we found no evidence that isolated rats were spatially impaired relative to pair-housed rats. We also found no difference in body weight, food intake or bar biting behaviour (indicators of welfare in rodents) between pair and isolated rats. We conclude that isolation housing causes insufficient stress to cause sex differences in spatial cognition.</p

Recording behaviour of indoor-housed farm animals automatically using machine vision technology: A systematic review

Large-scale phenotyping of animal behaviour traits is time consuming and has led to increased demand for technologies that can automate these procedures. Automated tracking of animals has been successful in controlled laboratory settings, but recording from animals in large groups in highly variable farm settings presents challenges. The aim of this review is to provide a systematic overview of the advances that have occurred in automated, high throughput image detection of farm animal behavioural traits with welfare and production implications. Peer-reviewed publications written in English were reviewed systematically following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. After identification, screening, and assessment for eligibility, 108 publications met these specifications and were included for qualitative synthesis. Data collected from the papers included camera specifications, housing conditions, group size, algorithm details, procedures, and results. Most studies utilized standard digital colour video cameras for data collection, with increasing use of 3D cameras in papers published after 2013. Papers including pigs (across production stages) were the most common (n = 63). The most common behaviours recorded included activity level, area occupancy, aggression, gait scores, resource use, and posture. Our review revealed many overlaps in methods applied to analysing behaviour, and most studies started from scratch instead of building upon previous work. Training and validation sample sizes were generally small (mean±s.d. groups = 3.8±5.8) and in data collection and testing took place in relatively controlled environments. To advance our ability to automatically phenotype behaviour, future research should build upon existing knowledge and validate technology under commercial settings and publications should explicitly describe recording conditions in detail to allow studies to be reproduced.status: Published onlin