Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Five scale challenges in Ecuadorian forest and landscape restoration governance
    Wiegant, Daniel ; Peralvo, Manuel ; Oel, Pieter van; Dewulf, Art - \ 2020
    Land Use Policy 96 (2020). - ISSN 0264-8377
    Forest and landscape restoration governance - Policy - Scale challenges

    The forest and landscape restoration (FLR) targets set as part of the Bonn Challenge draw attention to the governance arrangements required to translate national FLR targets into local action. To achieve the targets, actors at multiple levels of the governance scale aim to influence relevant processes on the ecological scale. In this article, we focus on the scale challenges relating to the implementation of Ecuador's restoration targets, by analysing the implementation of the 2014–2017 National Forest Restoration Plan in the montane Chocó Andino and Bosque Seco landscapes. From 54 semi-structured interviews, a document review, and geographical data analysis, we identified two temporal (i, ii) and three spatial scale challenges (iii, iv, v): i) Political cycles mismatch with FLR timelines; ii) Planning horizons mismatch with FLR timelines; iii) National restoration objectives mismatch with decentralised land use planning realities; iv) The governance level of existing FLR efforts mismatches with the level receiving restoration funds; and v) Tensions exist between the spatial dimensions of biodiversity and water-related restoration efforts. The findings highlight that more attention must be given to scale-sensitive governance to make the process in which national FLR targets are translated into local action more effective.

    Five scale challenges in Ecuadorian landscape restoration governance
    Wiegant, Daniel ; Peralvo, M. ; Oel, P.R. van; Dewulf, A.R.P.J. - \ 2019
    Impacts of nutrients and pesticides from small- and large-scale agriculture on the water quality of Lake Ziway, Ethiopia
    Teklu, Berhan M. ; Hailu, Amare ; Wiegant, Daniel A. ; Scholten, Bernice S. ; Brink, Paul J. van den - \ 2018
    Environmental Science and Pollution Research 25 (2018)14. - ISSN 0944-1344 - p. 13207 - 13216.
    Lake Ziway - Monitoring - Pesticides - Physicochemical parameters - Risk assessment - Water quality

    The area around Lake Ziway in Ethiopia is going through a major agricultural transformation with both small-scale farmers and large horticultural companies using pesticides and fertilisers at an increased rate. To be able to understand how this influences the water quality of Lake Ziway, water quality data was gathered to study the dynamics of pesticide concentrations and physicochemical parameters for the years from 2009 to 2015. Results indicate that for some physicochemical parameters, including pH, potassium and iron, over 50 % of the values were above the maximum permissible limit of the Ethiopian standard for drinking water. The insecticide spiroxamine poses a high chronic risk when the water is used for drinking water, while the estimated intake of diazinon was approximately 50 % of the acceptable daily intake. Higher-tier risk assessment indicated that the fungicide spiroxamine poses a high acute risk to aquatic organisms, while possible acute risks were indicated for the insecticides deltamethrin and endosulfan. Longer-term monitoring needs to be established to show the water quality changes across time and space, and the current study can be used as a baseline measurement for further research in the area as well as an example for other surface water systems in Ethiopia and Africa.

    The challenge of evaluating health effects of organic food; operationalisation of a dynamic concept of health
    Huber, M.A.S. ; Bakker, M.H. ; Dijk, W. ; Prins, H.A.B. ; Wiegant, F.A.C. - \ 2012
    Journal of the Science of Food and Agriculture 92 (2012)14. - ISSN 0022-5142 - p. 2766 - 2773.
    nutrition-related health - cell-mediated-immunity - biological robustness - nervous-system - free-radicals - stress - exercise - biomarkers - immunomodulation - resilience
    The health benefits of consuming organically produced foods compared with conventional foods are unclear. Important obstacles to drawing clear conclusions in this field of research are (1) the lack of a clear operational definition of health and (2) the inability to distinguish between different levels of health using valid biomarkers. In this paper, some shortcomings of the current definition of health are outlined and the relevance of integrating a more dynamic and functional component is emphasised, which is reflected by the ability to adapt. The state of health could then be determined by challenging an individual with some form of stressor and by subsequent quantification and evaluation of the coherence in recovery of various physiological processes and parameters. A set of relevant parameters includes the activity of the immune system and the activity of the autonomous nervous system. A good recovery towards homeostasis is suggested to reflect a qualitatively good state of health. Furthermore, it would enable objective evaluation of health-optimising strategies, including the consumption of organically produced foods that aim to strengthen health. (C) 2012 Society of Chemical Industry
    Spatial learning in pigs: effects of environmental enrichment and individual characteristics on behaviour and performance
    Jansen, J. ; Bolhuis, J.E. ; Schouten, W.G.P. ; Spruijt, B.M. ; Wiegant, V.M. - \ 2009
    Animal Cognition 12 (2009)2. - ISSN 1435-9448 - p. 303 - 315.
    different coping characteristics - ranging domestic pigs - physiological-responses - detour behavior - growing pigs - rearing conditions - stress responses - female mice - sus-scrofa - memory
    This study investigated the effects of both environmental enrichment and individual behavioural characteristics on spatial cognitive capabilities of pigs, using a novel latent spatial learning paradigm based on Tolman's detour experiments (1948). Pigs were housed either in 'barren' pens or in pens enriched with straw bedding from birth. Pigs were restrained in a Backtest at 10 and 17 days postpartum. Based on their escape behaviour in this test, which has been shown to reflect their behavioural style, six 'high-resisting' (HR) and six 'low-resisting' (LR) pigs were selected from each housing environment (n = 24 in total). At 12 weeks of age, pairs of pen mates (LR and HR) were exposed to a maze three times (exploration trials). Pigs were then placed individually in the maze, and social reinstatement proved to be a strong incentive to find the exit leading to the home pen. We subsequently blocked the direct route to the exit, forcing animals to find a detour (memory test 1, MT1). This test was repeated once to investigate the relative improvement, i.e. detour learning (memory test 2, MT2). Housing condition and Backtest response strongly affected exploration patterns. In spite of this, no effects on performance during the subsequent memory tests were found. Performance was substantially improved in MT2, indicating that once a goal is apparent, pigs are able to solve a complex spatial memory task easily. In conclusion, social reinstatement provided a good incentive to complete a spatial task, and the substantial improvement in performance between MT1 and MT2 stresses the need for task complexity when testing spatial memory in pigs. Housing conditions or individual behavioural style did not affect spatial memory during MT1 or MT2. However, housing environment and behavioural style strongly affected explorative behaviour of pigs in an unfamiliar maze during both exploration trials and memory tests. This implicates that apparent effects of environmental enrichment on spatial learning and memory in pigs might reflect differences in explorative patterns rather than in cognitive processes.
    Cortisol administration to pregnant sows affects behaviour of their piglets
    Kranendonk, G. ; Mulder, E.J. ; Hopster, H. ; Wolthuis, M. ; Ekkel, E.D. ; Wiegant, V.M. ; Reenen, C.G. van; Taverne, M.A.M. - \ 2007
    In: 4th World Congress on Developmental Origins of Health & Disease, Utrecht The Netherlands 13-16 September, 2006. - - p. 542 - 542.
    Lower birth weight and attenuated adrenocortical response to ACTH in offspring from sows that orally received cortisol during gestation
    Kranendonk, G. ; Hopster, H. ; Fillerup, M. ; Ekkel, E.D. ; Mulder, E.J.H. ; Wiegant, V.M. ; Taverne, M.A.M. - \ 2006
    Domestic Animal Endocrinology 30 (2006)3. - ISSN 0739-7240 - p. 218 - 238.
    pituitary-adrenal axis - beta-hydroxysteroid dehydrogenase - prenatal stress - 11-beta-hydroxysteroid dehydrogenase - glucocorticoid exposure - adult-rats - growth restriction - fetal maturation - blood-pressure - genetic merit
    Prenatal stress is known to affect several offspring characteristics, but its effects depend among other factors on the period of gestation in which it is applied. In the present study, oral administration of hydrocortisone-acetate (HCA) was used to elevate cortisol concentrations in pregnant sows to levels also observed after psychological stress. HCA was administered during three different periods of gestation (115 days in pigs): period 1: 21¿50 (P1, n = 10), period 2: 51¿80 (P2, n = 10) and period 3: 81¿110 (P3, n = 10) days after insemination. Control sows (n = 11) received vehicle from 21¿110 days after insemination. When P1-, P2- and P3-sows did not receive HCA, they also received vehicle. During gestation, weekly saliva samples were taken from the sows to determine salivary cortisol concentrations. Treatment effects on sow, litter and piglet characteristics were determined. In addition, two female piglets per litter were subjected to an ACTH-challenge test at 6 weeks of age to determine the adrenocortical response to ACTH. Pigs were slaughtered at 6 months of age and slaughter weight, back fat thickness and percentage of lean meat were analysed. During the period of treatment with HCA, salivary cortisol concentrations were increased in P1-, P2- and P3-sows compared to control sows (P <0.01). The total number of piglets born per litter did not differ among treatment groups (P > 0.30), but pooled HCA-litters had a higher percentage of live born piglets (P <0.05) and fewer mummies than control litters (P <0.05). Gestation length did not differ among treatment groups (P = 0.21), but did affect treatment effects on birth weight. Overall, HCA-piglets weighed less at birth, and remained lighter until weaning (P <0.05). The salivary cortisol concentrations after i.m. injection of ACTH (2.5 IU/kg) were lower in P1- and P3-piglets compared to control piglets. At slaughter, HCA-treatment indirectly decreased lean meat percentage and increased back fat thickness. In conclusion, elevated peripheral cortisol concentrations in pregnant sows affect both litter characteristics and piglet physiology, the latter depending on the period of gestation during which concentrations were elevated. Underlying mechanisms require further investigation.
    Stress, depression and hippocampal apoptosis
    Lucassen, P.J. ; Heine, V.M. ; Muller, M.B. ; Beek, E.M. van der; Wiegant, V.M. ; Kloet, E.R. de; Joels, M. ; Fuchs, E. ; Swaab, D.F. ; Czeh, B. - \ 2006
    CNS & Neurological Disorders 5 (2006)5. - ISSN 1871-5273 - p. 531 - 546.
    In this review, we summarize and discuss recent studies on structural plasticity changes, particularly apoptosis, in the mammalian hippocampus in relation to stress and depression. Apoptosis continues to occur, yet with very low numbers, in the adult hippocampal dentate gyrus (DG) of various species. Stress and steroid exposure modulate the rate of apoptosis in the DG. Contrary to earlier studies, the impact of chronic stress on structural parameters of the hippocampus like cell number and volume, is rather modest, and requires prolonged and severe stress exposure before only small reductions (<10 %) become detectable. This does not exclude other structural parameters, like synaptic terminal structure, or dendritic arborization from being significantly altered in critical hippocampal subregions like the DG and/or CA3. Neither does it imply that the functional implications of the changes after stress are also modest. Of interest, most of the structural plasticity changes appear trasient and are generally reversible after appropiate recovery periods, or following cessation or blockade of the stress or corticosteroid exposure. The temporary slowing down of both apoptosis and adult proliferation, i.e. the DG turnover, after chronic stress will affect the overall composition, average age and identity of DG cells, and will have considerable consequences for the connectivity, input and properties of the hippcampal circuit and thus for memory function. Modulation of apoptosis and neurogenesis, by drugs interfering with stress components like MR and/or GR, and/or mediators of the cell death cascade, may thererfore provide drug targets for the modulation of mood and memory
    Effects of rearing and housing environment on behaviour and performance of pigs with different coping characteristics
    Bolhuis, J.E. ; Schouten, W.G.P. ; Schrama, J.W. ; Wiegant, V.M. - \ 2006
    Applied Animal Behaviour Science 101 (2006)1-2. - ISSN 0168-1591 - p. 68 - 85.
    growing pigs - disintegration method - agonistic behavior - weaned pigs - pen size - enrichment - welfare - straw - productivity - provision
    The availability of a rooting substrate may profoundly affect behaviour and welfare of pigs. Apart from their actual housing environment, also the conditions present in early life and individual characteristics may influence the behaviour of pigs. The present study investigated the relative importance of the housing environment during rearing and the actual housing environment on behaviour during the finishing phase, pathological lesions of the heart and stomach wall and weight gain in pigs with diverging coping characteristics. Pigs were reared either without a rooting substrate (barren, B) or in identical pens enriched with straw bedding (enriched, E). During the suckling period piglets were subjected to the Backtest. The Backtest classification of pigs is, to a certain extent, predictive of their coping style. Each piglet was restrained in supine position for 1 min and its resistance (i.e. the number of escape attempts) was scored. Sixty high-resisting (HR) and 60 low-resisting (LR) pigs were selected. Half of these pigs were from barren and the other half from enriched rearing environments. Pigs were housed in groups of six (three HR and three LR) after weaning. At 10 weeks of age, environmental conditions (B or E) were switched for half of the pens. Behaviour patterns of pigs during the finishing phase were largely determined by the actual presence or absence of straw bedding. Pigs that changed from enriched to barren pens (EB pigs), however, showed an increased inactivity beyond the inactivity levels of pigs with a barren rearing history (BB pigs). The impact of rearing history on chewing, manipulative and play behaviour in later life was larger for LR than for HR pigs. The availability of straw reduced the occurrence of gastric lesions in LR, but not in HR pigs. Feed intake tended to be lower in EB pens than in EE pens, but this was reflected in the growth rate of HR pigs only. HR-EE pigs showed a higher weight gain than HR-EB pigs. In conclusion, behaviour patterns of pigs were largely influenced by the actual (in)availability of straw. The influence of rearing history on behaviour, occurrence of gastric lesions and weight gain was smaller, and depended to some extent on coping characteristics (LR or HR) of the pigs under study
    Behavioural development of pigs with different coping characteristics in barren and substrate-enriched housing conditions
    Bolhuis, J.E. ; Schouten, W.G.P. ; Schrama, J.W. ; Wiegant, V.M. - \ 2005
    Applied Animal Behaviour Science 93 (2005)3-4. - ISSN 0168-1591 - p. 213 - 228.
    male great tits - environmental enrichment - individual-differences - growing pigs - social challenges - animal-welfare - play - responses - piglets - stress
    Characterization of piglets based on the degree of resistance they display in a so-called Backtest is, to a certain extent, predictive of their coping responses to several challenges in later life. It is unknown, however, whether these individual coping characteristics of pigs are also reflected in their behavioural development in different environments. The present study investigated the behavioural development of pigs with diverging Backtest responses, high-resisting (HR) and low-resisting (LR) pigs, in both barren housing and housing enriched with straw bedding. During the suckling period, pigs were subjected to the Backtest. Pigs classified as HR (n = 30) or LR (n = 30) were selected and after weaning housed in groups of six (three LR and three HR) in either barren or enriched pens. Home pen behaviour was recorded at 5, 9, 15 and 19 weeks of age for 8 h per week using 2-min instantaneous scan sampling. Housing environment markedly influenced behaviour of pigs. Barren housed pigs were less active, showed less explorative and play behaviour, and spent more time on oral activities directed at pen mates than pigs from enriched housing. HR pigs showed more aggressive behaviour than LR pigs and they tended to be less active in both environments. LR pigs spent more time on manipulating pen mates, in particular in barren housing. In addition, they played more than HR pigs in enriched pens. In conclusion, an enriched housing environment, i.e. availability of straw bedding, appeared to improve welfare as it increased play behaviour and decreased manipulative oral behaviour directed at pen mates in comparison with barren housing conditions. Individual coping characteristics of pigs, as assessed in the Backtest, were also reflected in their home pen behaviour. Notably, the effects of housing on both manipulative and play behaviour were most obvious in LR pigs.
    Individual coping characteristics, aggressiveness and fighting strategies in pigs
    Bolhuis, J.E. ; Schouten, W.G.P. ; Schrama, J.W. ; Wiegant, V.M. - \ 2005
    Animal Behaviour 69 (2005)5. - ISSN 0003-3472 - p. 1085 - 1091.
    group-housed sows - behavioral-characteristics - social-status - growing pigs - great tits - young-pigs - dominance - weight - responses - piglets
    Individual pigs, Sus scrofa, differ considerably in how aggressive they are during encounters with unfamiliar conspecifics. We examined whether individual coping characteristics of pigs were predictive of aggression during social encounters and the resulting social status. Piglets were subjected to the Backtest during the suckling period, as their behavioural response in this test seems to be predictive of their coping style. Each piglet was restrained in a supine position for 1 min and the resistance (i.e. number of escape attempts) was scored. After weaning, 30 `high-resisting¿ (HR) and 30 `low-resisting¿ (LR) pigs were regrouped with unfamiliar pigs of similar weight and we recorded their aggressive behaviour for 180 min. In addition, we assessed the social rank of each pig. HR pigs showed more aggressive behaviour than LR pigs: they initiated more fights, started fighting earlier and spent more time fighting during the observation period. HR and LR pigs did not differ, however, in achieved social rank. Level of self-initiated fighting was positively correlated with social rank in LR pigs, but this relation was not found in HR pigs. In conclusion, the coping style of pigs is related to their aggressive behaviour and the establishment of dominance relationships after mixing. Our results indicate that LR pigs are flexible in using aggression, whereas the high level of aggression of HR pigs regardless of their success in encounters suggests that these animals are more rigid in their aggressive behaviour.
    Neuronal Number, Volume, and Apoptosis of the Left Dentate Gyrus of Chronically Stressed Pigs Correlate Negatively With Basal Saliva Cortisol Levels
    Beek, E.M. van der; Wiegant, V.M. ; Schouten, W.G.P. ; Eerdenburg, F.J.C.M. van; Loijens, L.W.S. ; Plas, C. ; Benning, M.A. ; Vries, H. de; Kloet, E.R. de; Lucassen, P.J. - \ 2004
    Hippocampus 14 (2004)6. - ISSN 1050-9631 - p. 688 - 700.
    pituitary-adrenal axis - chronic psychosocial stress - unipolar major depression - granule cell layer - hippocampal volume - glucocorticoid-receptors - postnatal-development - stereotyped behavior - alzheimers-disease - hypoxia-ischemia
    Although the consequences of stress and hypercortisolemia for the rodent hippocampal dentate gyrus (DG) are well known, little is known about other species. For pigs, tethered housing represents a well-established chronic stressor that shares many similarities with restraint paradigms, as evidenced by profound changes in behavior and autonomic and endocrine dysfunction, including flattened cortisol rhythms and hypercortisolemia all conditions that may threaten hippocampal viability in rat. Here, we studied structural parameters of the porcine DG after 5 months of tethered housing in relation to basal saliva cortisol measured antemortem. We further investigated whether any neuropathology or alterations in apoptosis had occurred in the left hippocampal hemisphere. Stereological analysis revealed high correlations between DG volume and neuron number in individual animals in both hemispheres. Within individual animals, neuron numbers of the left and right lobes were not correlated. Notably, basal cortisol was negatively correlated with volume and neuron number of the left, but not the right DG. Although obvious neuropathology was absent, apoptosis was present in DG and alveus and less so in CA areas. Despite the short window of time during which apoptosis is detectable, their stereologically estimated numbers in the DG, but not in other regions, were negatively correlated with cortisol. In conclusion, our data indicate for the first time a profound lateralization in the relationship between DG structure, apoptosis, and basal cortisol after stress in pigs. Five months of chronic stress failed to induce lasting neuropathology. Although accumulating changes in apoptosis could have contributed to the structural DG alterations, further studies should reveal whether stress has been instrumental, or whether the differences between animals were present from birth onward. The present lateralization after stress is, however, consistent with lateralized hippocampal volume changes in stress-related human disorders and suggests that these effects are not limited to this species alone.
    Personalities in pigs: Individual characteristics and coping with environmental challenges
    Bolhuis, J.E. - \ 2004
    Wageningen University. Promotor(en): V.M. Wiegant, co-promotor(en): W.G.P. Schouten; Johan Schrama. - [S.l.] : S.n. - ISBN 9789085040620 - 176
    varkens - persoonlijkheid - karakterisering - individuele kenmerken - stress - stressreactie - varkensstallen - adaptatie - diergedrag - dierenwelzijn - milieu - verrijking - immuniteitsreactie - dierfysiologie - pigs - personality - characterization - individual characteristics - stress - stress response - pig housing - adaptation - animal behaviour - animal welfare - environment - enrichment - immune response - animal physiology
    There are indications that pigs may have difficulty in adapting to the constraints of intensive housing conditions. Pigs show a wide variation in adaptive responses when exposed to the same stressful situation. Aim of this thesis was to investigate whether the behavioural coping responses of young piglets reflect and predict more general profiles of reactivity to challenges, often referred to as coping styles, under different rearing and housing conditions. For this purpose, pigs were characterized early in life as `high-resisting` (HR) or `low-resisting` (LR) on the basis of their resistance response in a so-called Backtest, in which they were manually restrained in supine position. The major part of the thesis focused on the interaction between these individual coping characteristics of pigs and their housing environment, which was either barren or enriched with straw bedding. The experiments described in this thesis show that HR pigs are more aggressive than LR pigs and less flexible in adapting their behaviour to environmental changes. As the two types of pig differed in response to the dopamine-agonist apomorphine, some initial evidence is provided for a neurochemical background of these behavioural differences. In addition, individual coping or personality characteristics of pigs were reflected in immune reactivity and in their home pen behaviour in barren and enriched environments. HR and LR pigs adapted differently to barren housing conditions. Moreover, individual characteristics modulated the effects of rearing and housing conditions on the behavioural response to novelty, immune reactivity, prevalence of gastric lesions and behavioural development. Remarkably, for almost all of the variables that were affected by housing environment, the impact was much larger for LR than for HR pigs. Thus, individual characteristics of pigs affect their performance in different environments and should be taken into account when studying the impact of housing on their behaviour and welfare. The knowledge of individual coping or personality characteristics could be extended and used for finding the optimal match between pigs and their social and physical environment in pig husbandry.
    Backtest type and housing condition of pigs influence energy metabolism
    Geverink, N.A. ; Heetkamp, M.J.W. ; Schouten, W.G.P. ; Wiegant, V.M. ; Schrama, J.W. - \ 2004
    Journal of Animal Science 82 (2004)4. - ISSN 0021-8812 - p. 1227 - 1233.
    environment interactions - individual-differences - manual restraint - breeding gilts - pregnant sows - coping styles - laying hens - behavior - system - physiology
    The behavioral response of piglets in a backtest early in life seems indicative of their coping strategy at a later age. Coping characteristics may depend on the interaction between backtest classification and housing conditions. We studied whether growth rate and partitioning of energy in adult gilts were related to response in the backtest early in life, and to housing in groups or individual stalls. During the suckling period, female piglets were subjected to the backtest. Each piglet was restrained on its back for 1 min, and the number of escape attempts was scored. Thirty-six high-resisting gilts and 36 low-resisting gilts were selected. After weaning, pigs were housed in 12 groups of six (three high-resisting and three low-resisting). From 7 mo of age onward, 36 gilts out of six groups were housed in individual stalls, whereas the other gilts remained group housed. At 13 mo of age, gilts were housed in clusters of three (three high-resisting or three low-resisting) for an experimental period of 7 d in climatic respiration chambers. Group-housed gilts were loose housed, and stall-housed gilts were housed in stalls within the chamber. Despite the fact that high-resisting and low-resisting gilts did not differ (P = 0. 269) in initial BW, low-resisting gilts showed a higher (P = 0.039) ADG during the experimental period in association with a higher (P = 0.043) energy metabolizability. This suggests that, in line with the theory on coping strategies, high-resisting gilts may have more difficulties in adapting to a change in environment, (i.e., the change from home pen to climatic chamber). Group-and stall-housed gilts differed (P = 0.001) in initial BW, with group-housed gilts being heavier. During the experimental period, stall-housed gilts showed lower energy metabolizability (P = 0.001), lower energy retention (P = 0.001), and a higher energy requirement for maintenance (P = 0. 001) due to a higher activity-related heat production (P = 0.001). This finding suggests that stall housing might have a negative influence on performance and partitioning of energy when animals are adapting to a change in their environment.
    Effect of response to backtest and housing condition on cell-mediated and humoral immunity in adult pigs
    Geverink, N.A. ; Parmentier, H.K. ; Vries Reilingh, G. de; Schouten, W.G.P. ; Gort, G. ; Wiegant, V.M. - \ 2004
    Physiology and Behavior 80 (2004)4. - ISSN 0031-9384 - p. 541 - 546.
    individual-differences - coping characteristics - manual restraint - breeding gilts - laying hens - cortisol - stress - behavior - strategies - aggression
    Several recent studies in juvenile pigs demonstrated a relationship between the degree of resistance displayed early in life in a so-called "backtest" and parameters of cell-mediated and humoral immunity. Some of the immune characteristics were reported to depend on the interaction between backtest classification and housing system. In the present study, the effects of backtest classification and housing condition on immune reactivity in adult gilts were examined. At 10 and 17 days of age, female piglets were subjected to the backtest. In this test, each piglet is restrained on its back for 1 min and the number of escape attempts is scored. Pigs classified as high resisting (HR) or low resisting (LR) were selected and housed in groups of six gilts. At 7 months of age, half of the gilts were housed in individual stalls. At 12 months of age, gilts were challenged by immunization with DNP-KLH. Control gilts were treated similarly with a placebo. Blood samples were drawn prior to immunization (Day 0) and weekly thereafter until Day 28. No significant effects of backtest type on cellular and Immoral responses against KLH were found. Furthermore, being housed in stalls as compared to groups had no consequences for the immune response and did not induce differences between HR and LR gilts. Differences in behavior and physiology found previously between HR and LR gilts, particularly in gilts in stall housing, may thus be of relatively little importance for immune-related health. (C) 2003 Elsevier Inc. All rights reserved.
    Individual coping characteristics, rearing conditions and behavioural flexibility in pigs
    Bolhuis, J.E. ; Schouten, W.G.P. ; Leeuw, J.A. de; Schrama, J.W. ; Wiegant, V.M. - \ 2004
    Behavioural Brain Research 152 (2004). - ISSN 0166-4328 - p. 351 - 360.
    male great tits - environmental enrichment - basal ganglia - growing-pigs - physiological-responses - memory-systems - breeding gilts - apomorphine - rat - exploration
    Several studies suggest that classification of piglets early in life based on the degree of resistance they display in a so-called Backtest may be indicative of their coping style at a later age. In the present study behavioural flexibility was investigated in pigs diverging for Backtest response and housing environment during rearing. Pigs were housed either without a rooting substrate (barren housing, 13) or in identical pens enriched with deep straw bedding (enriched housing, E) from birth. During the suckling period piglets were subjected to the Backtest. Each piglet was restrained on its back for I min and the resistance (i.e. number of escape attempts) was scored. Pigs classified as 'high-resisting' (HR) or as 'low-resisting' (LR) were subjected to a simple (left/right) spatial discrimination (T-maze) task at 8 weeks of age. The effect of a single, subtle intramaze change was determined after acquisition of the task. In addition, pigs were subjected to reversal learning to assess their ability to modulate established behaviour patterns. Housing and its interaction with Backtest classification influenced the behavioural response to the intramaze change: E pigs were considerably more distracted than B pigs. Housing condition affected LR pigs more than HR pigs, as indicated by the interaction effects on various recorded behaviours. These interactions indicate that behavioural responding of pigs with diverging coping characteristics cannot simply be generalised across rearing conditions. Furthermore, FIR pigs were less successful in reversal learning than LR pigs, suggesting that they have a higher propensity to develop inflexible behavioural routines. (C) 2003 Elsevier B.V. All rights reserved.
    Neuroendocrine adaptation to stress in pigs, CRH and vasopressin in the paraventricular nucleus
    Karman, A.G. - \ 2003
    Wageningen University. Promotor(en): V.M. Wiegant, co-promotor(en): E.M. van der Beek. - [S.I.] : S.n. - ISBN 9789058089304 - 157
    varkens - stress - stressreactie - neurofysiologie - endocrinologie - adaptatie - neuropeptiden - vasopressine - corticoliberine - hypothalamus - persoonlijkheid - individuele kenmerken - diergedrag - neurobiologie - pigs - stress - stress response - neurophysiology - endocrinology - adaptation - neuropeptides - vasopressin - corticoliberin - hypothalamus - personality - individual characteristics - animal behaviour - neurobiology
    Differences in coping strategy present at birth as well as housing conditions may influence autonomic and endocrine stress responses.In rodents,corticotropin-releasing hormone (CRH) and vasopressin (VP) signaling in theparaventricularnucleus (PVN) plays an important role in stress responses.Stress is known to induce expression of VP in PVN-CRH neurons, with the degree of VP expression relating to duration and intensity of the stress.Moreover, there is evidence that the activity of these systems is altered in stress-induced sensitization. This suggests that the functional state of CRH and VP systems, likely also in the pig PVN, could be used as a neurobiological index of stress vulnerability.

    The aim of the thesis was to asses in pigs the effects ofindividual coping strategy (high and low resisting, HR and LR respectively), and rearing and housing conditions on the susceptibility of pigs to stress sensitization.Changes in CRH and VP expression in the PVN were studied in female and also male pigs with different coping strategies subjected to different housing conditions using immunocytochemistry and in situ hybridization techniques.

    We found a clear sex difference in both CRH and VP peptide content in the PVN, i.e. male pigs showed higher VP and CRH peptide content compared to female pigs. This confirms and extends previous reports of the existence of a sexually dimorphic regulation of the HPA axis.The results of this studysuggests that the housing conditions tested, although they clearly affected some behavioral and endocrine parameters, were not contrasting enough with respects to stress load to result in changes in the activity of the HPA axis at the hypothalamic level. Individual housing (IND), however, did affect the HPA axis, with a clear, coping strategy dependent difference on VP peptide and CRH mRNA, but not on CRH peptide levels. The PVN inIND HR pigs contained higher VP peptide levels compared to group housed (GRO) HR and IND LR gilts. Moreover, we found that the absolute number, but not the percentage of cells showing co-localization of VP and CRH peptide was increased in IND HR gilts compared to GRO HR gilts.We suggest that the higherlevels of VP peptide in the medial region of the PVN in IND HR pigs playsa role inpotentiatingthe actions of CRH to stimulate ACTH secretion from the anterior pituitary.Furthermore, IND LR gilts showed increased levels of CRH mRNA compared to GRO LR and IND HR gilts, which suggests that LR pigs react to chronic housing stress with an up-regulation of CRH transcription.

    The experiments described in this thesis provide evidence that pigs characterized with different coping strategies at early age, differ as adults in the way they adapt to individual housing at the level of the PVN. The differences found in CRH and VP levels in the PVN support the differences in basal behavioral and physiological variables between these animals that became evident under chronic stress. Moreover, the changes in activity of CRH and VP observed are reminiscent to those observed in human psychopathology (e.g. depression), suggesting that these changes may be interpreted as (pre) pathological signs in the pig. This suggests that individual housing is not an optimal housing condition for both HR and LR pigs. Based on these results, we conclude that housing condition likely increases the susceptibility to stress in both HR and LR gilts. Selection of pigs for coping strategy to maintain common practice of individual housing of breeding pigs will therefore not benefit the welfare of the animals. To improve pig welfare and minimize the risk of stress-related diseases, the focus should be on optimizing the pigs' housing conditions.

    Fertility, aging and the brain neuroendocrinological studies in female rats
    Franke, A.N. - \ 2003
    Wageningen University. Promotor(en): V.M. Wiegant, co-promotor(en): E.M. van der Beek. - [S.l.] : S.n. - ISBN 9789058088796 - 176
    ratten - vruchtbaarheid - voortplantingsvermogen - verouderen - hersenen - neurofysiologie - endocrinologie - rats - fertility - reproductive performance - aging - brain - neurophysiology - endocrinology
    It is well known that fertility decreases in female mammals with advancing age. In women this decrease already starts around the age of 30 and shows a large variation between individuals. The aim of this thesis was to elucidate changes in the reproductive system, especially in the brain, that may underlie the early decline in fertility with age. To this end,neuroendocrinologicalstudies were performed in young and middle-aged females of two rat strains known to differ in the onset of infertility: theWistar(WU) and (UxRP)F1strain.

    The results of the present thesis confirm the idea that the attenuation of theluteinizinghormone (LH) surge is one of the first indications of reproductive aging in rats. The LH surge is responsible for ovulation. It is induced by feedback mechanisms of ovarian steroid hormonesestradioland progesterone on the brain (i.e. on the secretion ofgonadotropin-releasing hormone) and pituitary gland (i.e. on the secretion of LH and follicle-stimulating hormone (FSH)) that become operative when the ovarian follicles are matured, and involves estrogen and progesterone receptors in the brain.

    Our results indicate that the attenuation of the LH surge in middle-aged rats likely results from an altered response of the brain toestradioland possibly also progesterone feedback, since we found a dramatic decrease in the number ofestradioland progesterone-containing neurons in several brain areas known to be crucially involved inneuroendocrineregulation of the reproductive axis. In contrast,estradioland progesterone levels were increased ((UxRP)F1) or even unchanged (Wistar) and the pituitary LH response toGnRHas well as the follicular progesterone production during the LH surge appeared to be comparable between young and middle-aged rats. This suggests that pituitary and ovary functions were still intact. Therefore, changes at the level of the brain may be at the start of the decline in fertility with age in rats.

    Interestingly, we found strain differences in the regulation of the reproductive axis. There was, for instance, a difference between F1 andWistarrats in the magnitude of the LH surge (F1>Wistar) and the magnitude of the pituitary LH response toGnRH(F1<Wistar). Also, middle-aged F1 rats appeared to be reproductively aged to a further extend compared toWistarrats, as judged by the number of changes in the reproductive system.

    Although in women ovarian aging appears to be the dominant reason for fertility decline, there is evidence for considerable variation between individuals in the mechanisms underlying reproductive aging. Based on our present findings and literature, we hypothesize that hypothalamic aging may also contribute to the decline in fertility in some women.

    Individual differences in behaviour, physiology and pathology in breedings gilts housed in groups or stalls
    Geverink, N.A. ; Schouten, W.G.P. ; Gort, G. ; Wiegant, V.M. - \ 2003
    Applied Animal Behaviour Science 81 (2003)1. - ISSN 0168-1591 - p. 29 - 41.
    different coping characteristics - circadian-rhythm - growing pigs - manual restraint - ordinal data - laying hens - heart-rate - stress - strategies - responses
    A number of studies in young pigs have demonstrated a relation between a variety of behavioural and physiological features and the degree of resistance displayed early in life in a so-called ''backtest''. The current study aimed at investigating the relation between the backtest response and the development of stereotypies, the circadian rhythm of cortisol, the heart rate response to feeding, and pathological lesions of heart, lungs and stomach of adult breeding gilts.At 10 and 17 days of age, female piglets were subjected to the backtest. In this test, each piglet is restrained on its back for 1min and the number of escape attempts is scored. Pigs classified as high-resisting (HR, n=36) or low-resisting (LR, n=36) were selected and housed in groups of six (3 HR, 3 LR). At 7 months of age, half of the groups were housed in individual stalls.Time spent chain biting by stall-housed gilts during 2h after afternoon feeding was studied at regular intervals for 21 weeks. At 11 months of age, saliva was collected from all animals every hour during 24h for cortisol analysis. At 8 and at 12 months of age, heart rate of all animals was measured around afternoon feeding. Pigs were slaughtered at 14 months of age and heart, lungs and stomach were macroscopically examined.Over time, stall-housed HR gilts tended to show more chain biting, had lower circadian cortisol concentrations and showed a diminished heart rate response to feed delivery compared to LR gilts. In group-housed gilts, the circadian rhythm of cortisol and the heart rate response to feed delivery did not relate to the backtest response. Stall-housed gilts had lower circadian cortisol concentrations than group-housed gilts. The prevalence of pathological lesions was not influenced by backtest type. Stomach wall damage was more severe in stall-housed than in group-housed gilts
    Effects of housing and individual coping characteristics in immune responses of pigs
    Bolhuis, J.E. ; Parmentier, H.K. ; Schouten, W.G.P. ; Schrama, J.W. ; Wiegant, V.M. - \ 2003
    Physiology and Behavior 79 (2003). - ISSN 0031-9384 - p. 289 - 296.
    growing pigs - behavioral-characteristics - environmental enrichment - physiological-responses - cortisol concentration - social-status - housed pigs - stress - disease - susceptibility
    The impact of environmental factors on immune responses may be influenced by coping characteristics of the individuals under study. The behavioral response of pigs in a so-called Backrest early in life seems indicative of their coping style at a later age. The present study investigated the effects of housing, barren versus enriched, and coping style, as assessed by Backtest classification, on immune responses of pigs. Pigs were housed either without a rooting substrate (barren housing) or in identical pens enriched with deep straw bedding (enriched housing) from birth. During the suckling period, pigs were subjected to the Backtest. Each pig was restrained on its back for 1 min and the resistance (i.e., number of escape attempts) was scored. Pigs classified as 'high-' or 'low-resisting' (HR and LR, respectively) were immunized with di-nitrophenyl-conjugated keyhole limpet haemocyanin (DNP-KLH) at 9 weeks of age. Blood samples were drawn before immunization (Day 0) and weekly thereafter, until Day 35. KLH-specific lymphocyte proliferation following immunization was higher for HR pigs than for LR pigs. Housing did not affect proliferative responses. Housing and coping style interacted in their effect on KLH-specific humoral immune responses. LR pigs from barren housing showed higher KLH-specific antibody titers than LR pigs from enriched housing. Differently housed HR pigs, however, showed similar antibody titers. These findings support other research indicating that individual coping styles of pigs are reflected in their immune responses. More important, the present study demonstrates that effects of housing on humoral immune responses of pigs may differ for pigs with divergent coping styles.
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