Consequences of repeated early isolation in domestic piglets (Sus scrofa) on their behavioural, neuroendocrine, and immunological responses

Effects of environmental enrichment at different stages of life on stress physiology of pigs were investigated in a trial with 63 groups, each of four siblings. In each of the three growing phases (suckling 0 to 4 weeks of age, nursery 5 to 9 weeks, fattening 10 to 24 weeks) pens either were (5E) or were not (50) enriched. Accordingly, the treatments were (i) 000, (ii) E00, (iii) EE0, (iv) 00E, (v) 0EE and (vi) EEE. The enrichment material, renewed twice daily to leave a thin layer, consisted of wood shavings and chopped straw. Salivary cortisol was sampled hourly from 0700 to 1900 h at the age of 9 and 21 weeks. The presence of a circadian secretion rhythm was evaluated by an intra-assay coefficient of variation-based method. An adrenocorticotropic hormone test was performed at 21 weeks. Treatment effects on the odds of a physiological cortisol rhythm were assessed by logistic regression, and effects on cortisol concentrations with a repeated measures GLM. Substrateenrichment from 0 to 9 weeks of age increased the odds of a rhythm as compared to barren housing (odds ratio (OR) 5 30.0, P , 0.01). A flat cortisol secretion pattern may indicate chronic stress and/or delayed maturation of the rhythm. Barren as compared to enriched rearing (0 to 4 weeks of age) seemed to cause a blunted secretion rhythm at 21 weeks of age. Although behavioural and tail lesion observations provided support to the assumption that a blunted rhythm indicates chronic stress, the biological significance of these cortisol results needs confirmation in future studies.Keywords: pig, cortisol, environmental enrichment, early enrichment ImplicationsThe welfare of intensively housed pigs is a matter of public concern. A crowded and barren environment is known to cause signs of stress. This research was designed to investigate effects on stress physiology of a very moderate amount of bedding provided at different stages of the life of pigs raised for slaughter. The quality (wood shavings and chopped straw) and amount was chosen to be compatible with partly slatted pen floors and slurry manure systems. The results indicate that a small amount of bedding in early life (0 to 4 weeks of age) will prevent physiological signs of stress at a later age. Due to use of unestablished methods the biological significance of these results needs more evidence to be disclosed.

Section: Discussionmentioning

confidence: 99%

Environmental enrichment in early life affects cortisol patterns in growing pigs

Munsterhjelm

Valros

Heinonen

et al. 2010

“…One of the key causal mechanisms of this relationship is thought to be the general catabolic influence of high circulating cortisol on certain muscle types and fat cells (Sapolsky et al, 2000;Yoshioka et al, 2005). Overall health indicators were also assessed, as chronic stress is known to have a generally suppressive effect on the immune system (Monjan and Collector, 1977;Jasnow et al, 2001;Kanitz et al, 2004). Again, this association is mediated, at least in part, by glucocorticoids (Chrousos, 1995).…”

Section: Introductionmentioning

confidence: 99%

The impact of chronic environmental stressors on growing pigs, Sus scrofa (Part 1): stress physiology, production and play behaviour

O’Connor

Parker

McLeman

et al. 2010

Commercially farmed animals are frequently housed in conditions that impose a number of concurrent environmental stressors. For pigs housed indoors, elevated levels of mechanical noise, atmospheric ammonia and low light intensities are commonplace. This experiment examined the effects on growing pigs of chronic exposure to combinations of commercially relevant levels of these potential stressors. Four-week-old hybrid female pigs (n 5 224) were housed under experimentally manipulated conditions of nominally either ,5 or 20 ppm atmospheric concentration of ammonia (24 h), a light intensity of 40 lux or 200 lux (12 h) and mechanical noise at either <60 or 80 dB(A) (24 h) for 15 weeks in a fully factorial arrangement (2 3 ) of treatments. The response of pigs to these environmental factors was assessed using a suite of physiological, production and behavioural measures. These included indicators of hypothalamic-pituitary-adrenal (HPA) axis activation such as salivary cortisol and adrenal morphometry, as well as body weight, food conversion efficiency and general health scores. Play behaviour was recorded as it is thought to be inversely related to stress. Chronic exposure to ammonia produced the strongest effect, shown by lower concentrations of salivary cortisol and larger adrenal cortices in the pigs reared under 20 ppm ammonia, which may have been indicative of a period of HPA activation leading to a downregulation of cortisol production. The pigs in the ammoniated rooms also performed less play behaviour than pigs in non-ammoniated rooms. There was evidence for an interaction between high noise and ammonia on the health scores of pigs and for brighter light to ameliorate the effect of ammonia on salivary cortisol. However, there was no measurable impact of these potential stressors on the productivity of the pigs or any of the other physiological parameters measured. We conclude that there should be little concern in terms of performance about the physical stressors tested here, within current European Union legal limits. However, 20 ppm ammonia may have had an adverse influence on the well-being of growing pigs. In this study, all other aspects of the pigs' husbandry were optimal; therefore, it is possible that under less favourable conditions, more pronounced effects of ammonia, noise and dim light would be observed.

“…The physical and psychological stress associated with the fights activates stress systems such as the hypothalamo-pituitary-adrenal (HPA) axis and the sympathetic system, leading to increased plasma levels of cortisol and catecholamines , which in turn modulate animal physiology in order to cope with the new situation. In pigs, social stress or high cortisol concentrations can decrease weight gain (McGlone et al, 1993, Coutellier et al, 2007, lymphocyte proliferation (Kanitz et al, 2004), natural killer cell activity (McGlone et al, 1993;SalakJohnson et al, 1996), neutrophilic chemotaxis (Salak-Johnson et al, 1996) and antiviral immunity (de Groot et al, 2001). …”

Section: Introductionmentioning

confidence: 99%

Behavioural, endocrine and immune responses to repeated social stress in pregnant gilts

Couret

Otten

Puppe

et al. 2009

Pregnant sows are exposed to various stressors in intensive pig husbandry that may have negative consequences on their health, reproductive performances and welfare. Social stress is one of these challenges, because gestating sows have to be housed in groups according to EU guidelines (2001/88/CE). The purpose of this study was to determine the consequences of repeated social stress in pregnant female pigs on their behavioural, endocrine and immunological responses and on pregnancy outcome. Pregnant gilts were submitted to a repeated social stress procedure induced by housing unfamiliar gilts in pairs changed twice a week between days 77 and 105 of gestation (S group, n 5 18). Control gilts were housed in stable pairs during the same period (C group, n 5 18). Agonistic behaviour was observed during the first 3 h after each grouping. Skin lesions were numbered 2 h after each grouping. Salivary cortisol was measured before and repeatedly during the 4 weeks of grouping. Gilts were immunized against keyhole limpet haemocyanin (KLH) on days 81 and 95 of gestation. Immunoglobulins G against KLH, proliferative responses to concanavalin A, lipopolysaccharide, pokeweed mitogen and KLH and peripheral blood leukocyte numbers were evaluated 1 week before the first grouping and 3 days after the last one. Agonistic interactions and skin lesions were observed in S gilts at each grouping, although there was a decline between the first and the last grouping ( P , 0.05). The repeated social stress induced a sustained endocrine response as shown by elevated salivary cortisol levels from 1 to 48 h after grouping in S gilts compared to C gilts. The cellular as well as the humoral immunity and the leukocyte numbers were not influenced by social stress. Gestation length tended to be shorter in S gilts ( P 5 0.09), but litter size, piglet weight or mortality at birth were not affected. Variability of the response of S gilts to groupings was partly explained by their average success value determined according to the outcome (defeat or win) of all the groupings. In conclusion, our study demonstrates that the application of repeated social stress to pregnant gilts during the last third of their gestation repeatedly activates their hypothalamo-pituitary-adrenal axis but does not impair their immune function and pregnancy outcome.