Debeaking

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A White Leghorn pullet with a trimmed beak
A White Leghorn pullet with a trimmed beak
Another White Leghorn pullet, with natural beak
Another White Leghorn pullet, with natural beak

Debeaking, also called beak trimming is the partial removal of the beak of poultry, especially chickens and turkeys. Most commonly, the beak is shortened permanently, although regrowth can occur. The trimmed lower beak is somewhat longer than the upper beak. In egg laying strains of chickens, the length of the upper beak distal from the nostrils which remains following trimming, should be 2 to 3mm [1] The term “debeaking” implies that the entire beak is removed during the trimming process, when in reality, only half or less of the beak is removed.[2]

In some countries, such as the United States, beak trimming is common in egg-laying strains of chickens and turkeys as a preventive measure to reduce the incidence of cannibalism and improve livability. [3]; however, commercial broiler chickens are not routinely beak trimmed due to their docile nature. In some countries, beak trimming is done as a last resort where alternatives are considered not to be possible or appropriate.

In close confinement, cannibalism and aggression is common among turkeys, ducks, pheasants, quail, and egg laying strains of chickens of many breeds (including both heritage breeds and modern hybrids). The tendency to cannibalism varies among different strains of chickens, but does not manifest itself consistently. Some flocks of the same breed may be entirely free from cannibalism, while others, under the same management, may have a serious outbreak.

Mortalities mainly due to cannibalism can be up to 13 to 15% in egg laying flocks housed in aviaries. [4], straw yards [5], and free-range systems.[6] Because egg laying strains of chickens can be kept in smaller group sizes in caged systems, cannibalism is reduced [7] leading to a lowered trend in mortality as compared to non-cage systems.[8] Cannibalism among flocks is highly variable and when it is not problematic, then mortalities among production systems are similar.[9]

Contents

[edit] History

Beak trimming was developed at the Ohio Experiment Station in the 1930’s.[10] The original form was temporary, cutting roughly 1/4" off the beak. It was thought that the tip of the beak had no blood supply and presumably no sensation. The procedure was performed by hand with a sharp knife, either when deaths due to cannibalism became excessive, or when the problem was anticipated because of a history of cannibalism in the particular strain of chicken.

Cannibalism is a serious management problem dating back to the periods before intensive housing of poultry became popular. Poultry books written before vertical integration of the poultry industry describe the vices of poultry:

Chicks and adult birds' picking at each other until blood shows and then destroying one another by further picking is a source of great loss in many flocks, especially when kept in confinement .... The recommendation of the Ohio Experiment Station of cutting back the tip of the upper beak has been found to be effective until the beak grows out again. [11]

Cannibalism has two peaks in the life of a chicken; during the brooding period and at the onset of egg laying. The point-of-lay cannibalism is generally the most damaging and gets most of the attention. The temporary beak-trimming developed at the Ohio Experiment Station assumed that cannibalism was a phase, and that blunting the beak temporarily would be adequate.

Later the practice turned to permanent beak-trimming performed, using electrically heated blades in a beak-trimming machine, to provide a self-cauterizing cut. Hot blade machines are the most common tool used today to trim beaks though other methods are used or under investigation such as an electric soldering iron, cold blades, infrared, and lazers. The biobeaker which uses an electric current to burn a small hole in the upper beak is the preferred method for trimming the beaks of turkeys. [12]

[edit] Pros and cons of beak trimming

The pros and cons of the most common method of controlling cannibalism, beak trimming, are well documented. The disadvantages include acute stress and short-term and perhaps long-term pain following a beak trim. A bird’s ability to consume feed is impaired following beak trimming because of the new beak shape that the young bird must adapt to. The welfare advantages include reduced pecking, feather pulling, and cannibalism; better feather condition; decreased mortality; and a lower level of flock fearfulness and nervousness leading to less chronic stress. The welfare disadvantages are more applicable to the individual birds whose beaks are trimmed, while the welfare advantages are more relevant to the interactive flock.[13]

[edit] The pain of beak trimming

The beak contains nociceptors that sense pain and noxious stimuli. [14] Beak trimming excites nociceptors. Following a trim, the nociceptors in the beak stump show abnormal patterns of neural discharge, which has been interpreted as acute pain.[15] Neuromas are found in the healed stumps of birds beak trimmed at 5 weeks of age or older and in birds whose beaks are subjected to severe trimming.[16] Neuromas are defined as tangled masses of swollen regenerating axon sprouts. During healing, neuromas are formed as part of the normal regeneration process. Eventually, the nerve fibers regrow, the excess axon sprouts regress, and the neuromas disappear. If beak trimming is severe because of improper procedure or done in older birds, the neuromas may persist, and the emitted action potentials are abnormal,[17] which suggest that beak trimmed older birds may experience chronic pain. However, neuromas do not persist in the beaks of birds subjected to proper trimming at 10 days of age or earlier.[18] For this reason, when conservative beak trimming (50% or less of the beak) is done correctly in birds 10 days of age or younger, formation of neuromas is prevented and the keratinized tissue regenerates.[19]

[edit] Alternatives to beak trimming

A range of options have been proposed as possible alternatives to beak trimming including modifying the genetics of domesticated poultry to reduce cannibalistic tendencies. For confined housing where light control is possible, lowering light intensity so that birds cannot see each other as easily reduces antagonistic encounters and aggressive behaviour. Enrichment devices., introduced at an early age, as simple objects hung in a habitat can reduce aggressive behavior. Dividing the population into smaller group sizes reduces cannibalism. Proper body weight management that avoids underweight pullets reduces the probability of underweight pullets with uterine prolapse that leads to cloacal cannibalism.[20]

[edit] Footnotes

  1. ^ United Egg Producers Animal Husbandry Guidelines for U. S. Egg Laying Flocks, 2008
  2. ^ Glatz, 2005
  3. ^ Hester and Shea-Moore, 2003
  4. ^ Hill, 1986
  5. ^ Gibson et al., 1988
  6. ^ Keeling et al., 1988)
  7. ^ Appleby and Hughes, 1991; Abrahamsson and Tauson, 1995
  8. ^ Tauson et al., 2006
  9. ^ Appleby and Hughes, 1991
  10. ^ Kennard, 1937
  11. ^ Jull, 1938
  12. ^ Glatz, 2005
  13. ^ Hester and Shea-Moore, 2003
  14. ^ Breward, 1984; Gentle, 1992
  15. ^ Breward, 1984; 1985; Gentle, 1986
  16. ^ Lunam et al., 1996
  17. ^ Devour and Rappaport, 1990
  18. ^ Gentle et al., 1997
  19. ^ Kuenzel, 2007
  20. ^ Glatz, 2005

[edit] References

  • Appleby, M. C., and B. O. Hughes (1991) Welfare of laying hens in cages and alternative systems: Environmental, physical and behavioural aspects World's Poultry Science Journal 47:109-128.
  • Breward, J. (1984) Cutaneous nociceptors in the chicken beak Proceedings of the Journal of Physiology London 346: 56P.
  • Breward, J. (1985) An electrophysiological investigation of the effects of beak trimming in the domestic fowl (Gallus gallus domesticus) Ph.D. thesis, University of Edinburgh.
  • Devor, M., and Rappaport, Z.H. (1990) Pain Syndromes in Neurol., edited by H. L. Fields, Butterworths, London, p. 47.
  • Gentle, M.J. (1986) Beak trimming in poultry World’s Poultry Science Journal 42: 268-275.
  • Gentle, M.J. (1992) Pain in birds Animal Welfare 1:235-247.
  • Gentle, M.J., Hughes, B.O., Fox, A. and Waddington, D. (1997) Behavioural and anatomical consequences of two beak trimming methods in 1- and 10-d-old domestic chicks British Poultry Science 38: 453-463.
  • Gibson, S.W., P. Dun, and B.O. Hughes (1988). The performance and behaviour of laying fowls in a covered strawyard system Research and Development in Agriculture 5:153-163.
  • Glatz, P.C. (2005) Poultry Welfare Issues: Beak Trimming Nottingham University Press, Nottingham, United Kingdom.
  • Hester, P.Y. and Shea-Moore, M. (2003) Beak trimming egg-laying strains of chickens World’s Poultry Science Journal 59:458-474.
  • Hill, J.A. (1986) Egg production in alternative systems - a review of recent research in the UK Research and Development in Agriculture 3:13-18.
  • Jull, M.A. (1938) Poultry Husbandry, 2nd Edition. McGraw Hill, New York., page 346.
  • Keeling, L.J., B.O. Hughes, and P. Dun (1988) Performance of free range laying hens in a polythene house and their behaviour on range Farm Building Progress. 94:21-28.
  • Kennard, D.C. (1937). Chicken vices Bimonthly Bullentin. 184. Ohio Agricultural Experiment Station. 22:33-39.
  • Kuenzel, W.J. (2007) Neurobiological basis of sensory perception: Welfare implications of beak trimming Poultry Science 86:1273-1282.
  • Lunam, C.A., Glatz, P.C. and Hsu, Y-J. (1996) The absence of neuromas in beaks of adult hens after conservative trimming at hatch Australian Veterinary Journal 74:46-49.

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