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Foot pad dermatitis and hock burns on a broiler chicken, 2011

Hock burns are lesions found on the hock joints of chickens and other birds raised on broiler farms. They are considered a form of contact dermatitis.[1] These marks occur when the ammonia from the waste of other birds burns through the skin of the leg, leaving a brown ulcer mark.[2] The condition has been found to be a source of pain for birds, can cause mobility issues, and may increase the risk of bacterial diseases.[3][4][5] In severe cases, hock burns can cause visible scabs to form.[6]

Higher rates of hock burns are often used by observers as an indicator of what they see as worse animal welfare conditions.[5] This is in part due to how they occur more often in overcrowded conditions and in birds genetically modified to grow fast. Although the meat is still safe to eat, many processors now remove these marks as they discourage customers.[2]

Prevalence

Hock burns have been identified in birds in Northern Ireland since at least 1978. It appears to have been first described in the scientific literature in a brief account in 1983.[7] From 1984 to 1987, hock burns were identified in 21% of birds.[8] In the decades since its first identification, it has stayed at an overall increased level.[9]

The industry standard target is to have no more than 15% of a flock showing hock burns, but independent studies have found that incidents are more common.[10] In 2024, self-reported data suggests a prevalence of around one-third of farmed birds in the United Kingdom. Spot checks of stores by volunteers found higher rates of 74% for one store's supplier.[2] Researchers in 2005 doing store spot checks found similar rates of around 80% across the United Kingdom. The same researchers also discovered a potential methodological difference between spot check figures and other reported values. After talking with veterinary inspectors, they were told that some slaughterhouses only record large hock burns and do not pay attention to anything smaller.[11]

Hock burns are not limited to the United Kingdom. For instance, in Brazil, hock burns are one of the most frequent causes of carcass condemnation (inspector rejection of meat).[12] In Germany, one study found that over a third of conventional broilers had hock burns.[13]

Various animal rights and animal welfare groups have criticized the prevalence of hock burns. For instance, one poultry specialist at the RSPCA has called it concerning and "sadly too common" in intensive animal farming. Other groups, such as Open Cages, have called it a sign of larger issues within the industry.[2]

Contributing factors

A number of factors are known to contribute to higher rates of hock burns. These include using fast-growing birds, higher stocking densities, and high moisture levels in the litter where birds live.[14][15] Additionally, it has been found to be more common in male birds and more common in heavier birds.[16] Research suggests that many of the same factors also contribute to foot pad dermatitis, another similar condition. Hock burn and foot pad dermatitis are often found together in the same birds.[14]

Classification

While there is not a fully universal way to classify the severity of hock burn, several methods exist. The most common relies on visual data and is called the Welfare Quality Assessment Protocol.[17] This method puts cases on a five-point scale from zero to four, with zero being no evidence of hock burns and four showing the most severe lesions.[18] Another alternative method works similarly, but rates cases on a three-point scale.[19]

See also

References

  1. ^ Haslam, S.M.; Knowles, T.G.; Brown, S.N.; Wilkins, L.J.; Kestin, S.C.; Warriss, P.D.; Nicol, C.J. (19 Jun 2007). "Factors affecting the prevalence of foot pad dermatitis, hock burn and breast burn in broiler chicken". British Poultry Science. 48 (3): 264–275. doi:10.1080/00071660701371341. ISSN 0007-1668. PMID 17578688.
  2. ^ a b c d "Millions of store chickens suffer burns from excrement". BBC News. 29 February 2024. Retrieved 1 March 2024.
  3. ^ Kaukonen, Eija; Norring, Marianna; Valros, Anna (2016-10-08). "Effect of litter quality on foot pad dermatitis, hock burns and breast blisters in broiler breeders during the production period". Avian Pathology. 45 (6): 667–673. doi:10.1080/03079457.2016.1197377. ISSN 0307-9457. PMID 27258732.
  4. ^ Jacob, FG; Baracho, MS; Nääs, IA; Lima, NSD; Salgado, DD; Souza, R (September 2016). "Risk of Incidence of Hock Burn and Pododermatitis in Broilers Reared under Commercial Conditions". Revista Brasileira de Ciência Avícola. 18 (3): 357–362. doi:10.1590/1806-9061-2015-0183. hdl:20.500.12733/1267. ISSN 1516-635X.
  5. ^ a b Kwon, Byung-Yeon; Park, Jina; Kim, Da-Hye; Lee, Kyung-Woo (2024-04-05). "Assessment of Welfare Problems in Broilers: Focus on Musculoskeletal Problems Associated with Their Rapid Growth". Animals. 14 (7): 1116. doi:10.3390/ani14071116. ISSN 2076-2615. PMC 11011155. PMID 38612355.
  6. ^ Kjaer, J.B.; Su, G.; Nielsen, B.L.; Sørensen, P. (1 August 2006). "Foot Pad Dermatitis and Hock Burn in Broiler Chickens and Degree of Inheritance". Poultry Science. 85 (8): 1342–1348. doi:10.1093/ps/85.8.1342. ISSN 0032-5791. PMID 16903463.
  7. ^ Greene, Joan A.; McCracken, R.M.; Evans, R.T. (25 June 1984). "A contact dermatitis of broilers -clinical and pathological findings". Avian Pathology. 14 (1): 23–38. doi:10.1080/03079458508436205. ISSN 0307-9457. PMID 18766896.
  8. ^ Bruce, D.W.; McIlroy, S.G.; Goodall, E.A. (19 September 1989). "Epidemiology of a contact dermatitis of broilers". Avian Pathology. 19 (3): 523–537. doi:10.1080/03079459008418705. ISSN 0307-9457. PMID 18679963.
  9. ^ BESSEI, W. (1 September 2006). "Welfare of broilers: a review". World's Poultry Science Journal. 62 (3): 455. doi:10.1017/s0043933906001085. ISSN 0043-9339.
  10. ^ "Welfare plea over supermarket chickens". Manchester Evening News. 2005-07-25. Retrieved 2024-05-19.
  11. ^ Broom, D.M.; Reefmann *, N. (Aug 2005). "Chicken welfare as indicated by lesions on carcases in supermarkets". British Poultry Science. 46 (4): 407–414. doi:10.1080/00071660500181149. ISSN 0007-1668. PMID 16268097.
  12. ^ Jacob, Fg; Baracho, Ms; Nääs, Ia; Lima, Nsd; Salgado, Dd; Souza, R (Sep 2016). "Risk of Incidence of Hock Burn and Pododermatitis in Broilers Reared under Commercial Conditions". Revista Brasileira de Ciência Avícola. 18 (3): 357–362. doi:10.1590/1806-9061-2015-0183. hdl:20.500.12733/1267. ISSN 1516-635X.
  13. ^ Bergmann, Shana; Helen, Louton; Westermaier, Christine; Wilutzky, Katharina; Bender, Andreas; Bachmeier, Josef; Erhard, Michael; Rauch, Elke (2016-09-05). "Field trial on animal-based measures for animal welfare in slow growing broilers reared under an alternative concept suitable for the German market". Berl Münch Tierärztl Wochensch. 129 (Berl Münch Tierärztl Wochensch). doi:10.2376/0005-9366-16035.
  14. ^ a b Elson, H.A. (2015-09-01). "Poultry welfare in intensive and extensive production systems". World's Poultry Science Journal. 71 (3): 449–460. doi:10.1017/s0043933915002172. ISSN 0043-9339.
  15. ^ Tainika, Brian; Şekeroğlu, Ahmet; Akyol, Ahmet; Waithaka Ng’ang’a, Zacharia (2023-04-03). "Welfare issues in broiler chickens: overview". World's Poultry Science Journal. 79 (2): 285–329. doi:10.1080/00439339.2023.2175343. ISSN 0043-9339.
  16. ^ Shepherd, E.M.; Fairchild, B.D. (1 October 2010). "Footpad dermatitis in poultry". Poultry Science. 89 (10): 2043–2051. doi:10.3382/ps.2010-00770. PMID 20852093.
  17. ^ Louton, H.; Piller, A.; Bergmann, S.; Erhard, M.; Stracke, J.; Spindler, B.; Kemper, N.; Schmidt, P.; Schade, B.; Boehm, B.; Kappe, E.; Bachmeier, J.; Schwarzer, A. (2020-01-23). "Histologically validated scoring system for the assessment of hock burn in broilers". Avian Pathology. 49 (3): 230–242. doi:10.1080/03079457.2020.1712328. ISSN 0307-9457. PMID 31971459.
  18. ^ "Welfare Quality, Assessment Protocol for Poultry (Broilers, Laying Hens)" (guideline document). Lelystad, Netherlands: Welfare Quality consortium. January 2009. p. 26.
  19. ^ Skrbic, Zdenka; Pavlovski, Z.; Lukic, M.; Peric, L.; Milosevic, N. (2009). "The effect of stocking density on certain broiler welfare parameters". Biotehnologija U Stocarstvu. 25 (1–2): 11–21. doi:10.2298/bah0902011s. ISSN 1450-9156.
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