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Surgical castration of pigs affects the behavioural response to a low-dose lipopolysaccharide (LPS) challenge after weaning

By S. L. Moya, L. A. Boyle, P. B. Lynch, S. Arkins

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The objective of the present study was to evaluate the effect of an acute stressor in the early postnatal life of pigs, surgical castration, on post-weaning behaviour, and on the behavioural, endocrine and immune responses elicited by a low-dose lipopolysaccharide (LPS) challenge after weaning. At 5-days-of-age, 64 male piglets were randomly assigned to undergo surgical castration or were left untreated (treatment). Pigs were weaned at 28 days-of-age. Behaviour post-weaning and mixing was assessed during a 1-h period, during which agonistic interactions were recorded. One day post-weaning, pigs were injected intraperitoneally with a single dose of 0 or 5 micro g/kg of BW of LPS from Escherichia coli (challenge). Sickness behaviour was studied by scan sampling every 5 min for 45 min at 0, 1, 2, 3, 4, 6 and 8 h after the challenge. Blood samples were taken at 0, 2, 12 or 24 h after injection and were analysed for plasma concentrations of tumor necrosis factor-alpha (TNF- alpha ), interleukin-1beta (IL-1 beta ), C-reactive protein (CRP), serum amyloid A (SAA) and cortisol. Results showed that non-castrated pigs were more aggressive than castrated pigs immediately after weaning (P<0.05). Administration of LPS provoked behaviours characteristic of sickness including a reduction in general activity, as well as decreased eating and exploratory behaviours (P<0.05). These altered behaviours occurred predominantly 3-h post injection (P<0.05). Significant treatment by challenge interactions showed that castration reduced the occurrence of sickness behaviours induced by LPS, such as depressed general activity (P<0.01), anorexia (P<0.01) and reduced exploratory behaviours (P<0.05). LPS administration increased TNF- alpha levels (P<0.05), with peak concentrations 2 h after injection (P<0.01). CRP levels of LPS-treated pigs were higher than saline-treated animals at 12 h (P<0.05). LPS administration tended to increase plasma SAA levels (P<0.1), but did not increase cortisol levels (P>0.1). However, castration did not affect the response of pro-inflammatory cytokines, acute phase proteins and cortisol to the challenge. These results show that surgical castration reduces aggressiveness at weaning and affects specific sickness behaviours but not the endocrine and immune responses elicited by low-dose endotoxin challenge in weaned pigs.

Date 2008
Publication Title Applied Animal Behaviour Science
Volume 112
Issue 1/2
Pages 40-57
ISBN/ISSN 0168-1591
Language English
Author Address Pig Production Development Unit, Teagasc Research Centre, Moorepark, Fermoy, Co. Cork, Irish Republic.
Cite this work

Researchers should cite this work as follows:

  1. Aggression
  2. Animal behavior
  3. Animal husbandry
  4. Animal immunology
  5. Animal nutrition
  6. Animal physiology
  7. Antibodies
  8. Boars
  9. Castration
  10. Cortisol
  11. Cytokines
  12. Hydrocortisone
  13. Immune response
  14. Immunity reactions
  15. Immunogens
  16. Immunological reactions
  17. Males
  18. Mammals
  19. peer-reviewed
  20. proteins
  21. surgery
  22. Swine
  23. Tumors
  24. weaning
  1. peer-reviewed