The impact of chronic environmental stressors on growing pigs, Sus scrofa (Part 1): stress physiology, production and play behaviour
Publication Type: |
Journal Article |
Year of Publication: |
2010 |
Authors: |
E. A. O’Connor, M. O. Parker, M. A. McLeman, T. G. Demmers, J. C. Lowe, L. Cui, E. L. Davey, R. C. Owen, C. M. Wathes, S. M. Abeyesinghe |
Publication/Journal: |
animal |
Keywords: |
ammonia, light, noise, pigs, stress |
ISBN: |
1751-7311 1751-732X |
Abstract:
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 (n5224) 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.