Self-administration of an Analgesic Does Not Alleviate Pain in Beak Trimmed Chickens

  • Freire, Rafael (School of Rural Science and Agriculture, University of New England) ;
  • Glatz, Philip C. (Pig and Poultry Production Institute, South Australia Research and Development Institute) ;
  • Hinch, Geoff (School of Rural Science and Agriculture, University of New England)
  • Received : 2007.01.18
  • Accepted : 2007.05.22
  • Published : 2008.03.01


Beak trimming in laying hens is a routine practice in which about 1/3-1/2 of the upper and lower beak is removed with the aim of reducing cannibalism. This experiment aimed to identify if this procedure causes pain by examining self-administration of an analgesic (carprofen) and pecking behaviour in 80 laying pullets beak-trimmed by two different methods at one day of age using hot-blade cauterisation or infra-red cauterisation. We also tested a control treatment, pullets with intact beaks, and a positive control treatment of pullets beak trimmed at 10 weeks of age which were expected to experience some pain due to recent severing of the underlying nerves in the beak. At 11 weeks of age birds trimmed at 10 weeks of age pecked more (p<0.001) gently ($0.6{\pm}0.06N$) at a disc attached to a force-displacement transducer than birds trimmed at 1 day of age with an infra-red machine ($0.9{\pm}0.1N$) or a hot blade ($1.1{\pm}0.07N$) and intact birds ($1.2{\pm}0.1N$). Maximum force of pecks recorded was also lower (p<0.001) in birds trimmed at 10 weeks of age than birds trimmed at 1 day of age with an infra-red method or a hot blade and intact birds. However, the pecking force in birds trimmed at 10 weeks of age was not increased by providing them with analgesic-treated feed, though birds that ate more carprofen had a higher maximum force of peck (p = 0.03). Pecking force in birds beak-trimmed at 1 day of age was the same as the pecking force of intact birds, and was unaffected by feeding pullets carprofen. A method of self-administration of an analgesic had previously revealed that chickens in neuromuscular pain arising from lameness consumed more of a feed containing carprofen than healthy chickens. However, we found no evidence that beak-trimmed pullets consumed more carprofen-treated feed than pullets with an intact beak. It should be noted that the three beak trimming methods resulted in an average 34% reduction in beak length, considered a light trim, and is perhaps not representative of commercial birds where greater portions of the beak are removed. We conclude that although carprofen has been reported to have an analgesic effect on neuromuscular pain in chickens, it appears to have no analgesic effect on potential neuropathic pain arising from the nerves severed by a light beak trim.


Beak Trimming;Analgesic;Hens;Neuropathic Pain;Carprofen


Supported by : Poultry Cooperative Research Centre


  1. Breward, J. and M. J. Gentle. 1985. Neuroma formation and abnormal afferent nerve discharges after partial beak amputation (beak-trimming) in poultry. Experientia, 41:1132-1135.
  2. Cheng, H. W. 2006. Morphopathological changes and pain in beak trimmed laying hens. World's Poult. Sci. J. 62:41-52.
  3. Davis, G. S., K. E. Anderson and D. R. Jones. 2004. The effects of different beak trimming techniques on plasma corticosterone and performance criteria in single comb white leghorn hens. Poult. Sci. 83:1624-1628.
  4. Gentle, M. J. 1986. Neuroma formation following partial beak amputation (beak-trimming) in the chicken. Res. Vet. Sci. 41:383-385.
  5. Gentle, M. J., B. O. Hughes, A. Fox and D. Waddington. 1997. Behavioural and anatomical consequences of two beak trimming methods in 1- and 10-d-old domestic chicks. Br. Poult. Sci. 38:453-463
  6. Carey, J. B. and B. W. Lassiter. 1995. Influences of age at final beak trim on the productive performance of commercial layers. Poult. Sci. 74:615-619.
  7. Colpaert, F. C., J. P. Tarayre, M. Alliaga, L. A. B. Slot, N. Attal and W. Koek. 2001. Opiate self-administration as a measure of chronic nociceptive pain in arthritic rats. Pain, 91:33-45.
  8. Danbury, T. C., C. A. Weeks, J. P. Chambers, A. E. Waterman- Pearson and S. C. Kestin. 2000. Self-selection of the analgesic drug carprofen by lame broiler chickens. Vet. Rec. 14:307-311.
  9. Miao, Z. H., P. C. Glatz and Y. J. Ru. 2005. Free-range poultry production - a review. Asian-Aust. J. Anim. Sci. 18:113-132.
  10. vanLiere, D. W. 1995. Responsiveness to a novel preening stimulus long after partial beak amputation (beak trimming) in laying hens. Behav. Processes, 34:169-174.
  11. Wall, P. D. 1981. On the origin of pain associated with amputation. In: Phantom and stump pain (Ed. J. Siegfried and M. Zimmerman). Springer Verlag, Berlin. pp. 2-14.
  12. McGeown, D., T. C. Danbury, A. E. Waterman-Pearson and S. C. Kestin. 1999. Effect of carprofen on lameness in broiler chickens. Vet. Rec. 144:668-671.
  13. Megret, S., F. Rudeaux, J-M. Faure and M. Picard. 1996. The role of the beak in poultry. Effects of debeaking. INRA Prod. Anim. 9:113-119.
  14. Glatz, P. C., L. B. Murphy and A. P. Preston. 1992. Analgesic therapy of beak-trimmed chickens. Aust. Vet. J. 69:18-18.
  15. Kupers, R. and J. Gybels. 1995. The consumption of fentanyl is increased in rats with nociceptive but not neuropathic pain. Pain, 60:137-141.
  16. Lunam, C. A., P. C. Glatz and Y.-J. Hsu. 1996. The absence of neuromas in beaks of adult hens after conservative trimming at hatch. Aust. Vet. J. 74:46-49.
  17. Glatz, P. C. 1990. Effect of age of beak trimming on the production performance of hens. Aust. J. Exp. Agr. 30:349-355.
  18. Glatz, P. C. 2000. Beak trimming methods. Asian-Aust. J. Anim. Sci. 13:1619-1637.
  19. Zuberbueher, C. A, R. E. Messikommer and C. Wenk. 2002. Choice feeding of selenium-deficient laying hens affects diet selection, selenium intake and body weight. J. Nutr. 132:3411- 3417.

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