Review of the Effects of Stress on Reproduction in Pigs

Stig Einarsson and colleagues from the Swedish University of Agricultural Sciences in Uppsala have reviewed the published literature into the effects of stress on boars, sows and gilts. They found the effects of stress to be dependent on its type, timing, duration and genetic factors. Ovulation, expression of sexual behaviour and implantation of the embryo were the most sensitive reproductive processes to stress.
calendar icon 6 January 2009
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The manifestations of stress, defined as a biological response to an event that the individual perceives as a threat to its homeostasis, are commonly linked to enhanced activity of the hypothalamo-pituitary-adrenal (HPA) axis and the activation of the sympathetic adreno-medullary (SA) system. Activation of the HPA system results in the secretion of peptides from the hypothalamus, principally corticotropin releasing hormone (CRH), which stimulates the release of adrenocorticotropic hormone (ACTH) and beta-endorphin. ACTH induces the secretion of corticosteroids from the adrenal cortex, which can be seen in pigs exposed to acute physical and/or psychological stressors.

The present paper is a review of studies on the influence of stress on reproduction. The authors reviewed the literature on the effects of temperature and humidity on boars, sows and gilts, of short lactation and weaning, transportation/relocation, and various management factors.

They concluded that the effects of stress on reproduction depend on the critical timing of stress, the genetic predisposition to stress and the type of stress.

The effect of stress on reproduction is also influenced by the duration of the responses induced by various stressors. Prolonged or chronic stress usually results in inhibition of reproduction, while the effects of transient or acute stress in certain cases is stimulatory, e.g. anoestrus, but in most cases is of impairment for reproduction.

Most sensitive of the reproductive process are ovulation, expression of sexual behaviour and implantation of the embryo, since they are directly controlled by the neuroendocrine system.


Einarsson S., Y. Brandt, N. Lundeheim and A. Madej. Stress and its influence on reproduction in pigs: a review. Acta Veterinaria Scandinavica 2008, 50:48doi:10.1186/1751-0147-50-48

January 2009

Further Reading

- You can view the full provisional paper by clicking here.
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