Register      Login
Animal Production Science Animal Production Science Society
Food, fibre and pharmaceuticals from animals
REVIEW

Current methods and techniques of beak trimming laying hens, welfare issues and alternative approaches

Philip C. Glatz https://orcid.org/0000-0003-0736-8388 A C and Greg Underwood https://orcid.org/0000-0002-5391-9884 B
+ Author Affiliations
- Author Affiliations

A Consultant Scientist, 29 Russell Avenue, Hazelwood Park, SA 5066, Australia.

B Aves Consulting, PO Box 837, Gisborne, Vic. 3437, Australia.

C Corresponding author: Email: philglatz@internode.on.net

Animal Production Science 61(10) 968-989 https://doi.org/10.1071/AN19673
Submitted: 27 November 2019  Accepted: 24 June 2020   Published: 20 August 2020

Abstract

Beak trimming is used in the egg industry to prevent mortality from cannibalism and minimise injurious pecking, vent pecking, aggressive pecking at the head and all forms of feather pecking, although the practice does not completely reduce the damage. There are alternatives to beak trimming, but they have not been reliable in preventing injurious pecking. However, beak trimming should not be used without providing birds enriched indoor and outdoor environments. Even when birds are beak trimmed, providing enriched facilities is recommended. The two main methods of beak trimming are hot blade (HB) and infrared beak treatment (IRBT). HB trimming removes the beak tips and cauterises the beak stump. The IRBT method uses heat from an infrared lamp to treat the outer beak and the underlying tissue. Initially, the tips of the beak remain intact and then soften and wear as the bird uses its beak. In contrast, the HB method results in an open wound that takes 3 weeks to heal. Two major welfare issues arise from beak trimming. The first is loss of sensory input because of removal of or heat treatment of sensory receptors in the beak. The second issue is the potential for acute and chronic pain from severing or heat treatment of nerves. HB trimming initially results in acute pain but there is limited evidence for beak sensitivity in IRBT birds. The development of neuromas in the beak have been implicated as a cause of chronic pain after HB trimming. When birds are HB trimmed (one-half of upper beak; one-third of lower) in the first 10 days of life, neuromas will develop, but they will resolve, compared with birds trimmed at older ages. However, neuromas will not resolve in 10-day old birds if more than one-half of the beak is HB trimmed. While HB trimming is performed according to accreditation standards by removal of one-half the upper beak and one-third of the lower beak is considered excessive, it prevents beak regrowth and the need to subject birds to re-trimming and a second bout of acute pain from the beak wound. Current levels of IRBT to treat half of the beak using the vendors quality-assurance protocol have been implemented worldwide to ensure that neuroma formation is prevented; however, if severe levels of IRBT are used, acute pain and subsequent neuromas may persist. The main impact of beak trimming is how the bird uses its beak when it eats, drinks and pecks at other birds and the environment. Reduced feed intake after HB trimming indicates pain associated with pecking or difficulty in eating. HB-trimmed birds initially show an increase in listlessness and guarding behaviours and increased inactivity, which indicates pain. IRBT and HB-trimmed birds have fewer aggressive pecks at the head, and there is a reduction in severe feather pecking and better feather scores, which results in a large reduction in mortality. Depending on the severity of IRBT and HB trimming, the advantage of using IRBT is improved welfare.

Additional keywords: acute pain, animal behaviour, animal stress, animal welfare, chronic pain, code of practice, hot blade, IR beak treatment, poultry.


References

Andersen AE, Nafstad PHJ (1968) An electron microscopic investigation of the sensory organs in the hard palate region of the hen (Gallus domesticus). Zeitschrift für Zellforschung und Mikroskopische Anatomie 91, 391–401.
An electron microscopic investigation of the sensory organs in the hard palate region of the hen (Gallus domesticus).Crossref | GoogleScholarGoogle Scholar | 4894069PubMed |

Australian Egg Corporation (2014) ‘Coordinate and monitor production performance and environments for growing stock and egg production. Certificate III in agriculture.’ (Australian Egg Corporation Limited: Sydney, NSW, Australia)

Beak Trimming Action Group (BTAG) (2015) ‘Beak trimming action groups review.’ DEFRA Animal Welfare Team, September 2015. Available at http://data.parliament.uk/DepositedPapers/Files/DEP2015-0919/Beak_Trimming_Action_Group_Review_November_2015.pdf [Verified 24 November 2019]

Beecham JA, Farnsworth KD (1999) Animal group forces resulting from predator avoidance and competition minimization. Journal of Theoretical Biology 198, 533–548.
Animal group forces resulting from predator avoidance and competition minimization.Crossref | GoogleScholarGoogle Scholar | 10373353PubMed |

Bell DD, Adams CJ (1998) Environment enrichment devices for caged layer hens. Applied Poultry Science 7, 19–26.
Environment enrichment devices for caged layer hens.Crossref | GoogleScholarGoogle Scholar |

Bestman MWP, Wagenaar JP (2003) Farm level factors associated with feather pecking in organic laying hens. Livestock Production Science 80, 133–140.
Farm level factors associated with feather pecking in organic laying hens.Crossref | GoogleScholarGoogle Scholar |

Bestman MWP, Wagenaar JP (2006) Feather pecking in organic rearing hens. Poster at ‘Joint Organic Congress’, 30–31 May, Odense, Denmark. (International Centre for Research in Organic Food Systems (ICROFS): Tiele, Denmark)

Bestman M, Koene P, Wagenaar JP (2009) Influence of farm factors on the occurrence of feather pecking in organic reared hens and their predictability for feather pecking in the laying period. Applied Animal Behaviour Science 121, 120–125.
Influence of farm factors on the occurrence of feather pecking in organic reared hens and their predictability for feather pecking in the laying period.Crossref | GoogleScholarGoogle Scholar |

Blokhuis HJ, Van Niekerk TF, Bessei W, Elson A, Guemene D, Kjaer JB, Levrino GAM, Nicol CJ, Tauson R, Weeks CA, Van De Weerd HA (2007) The LayWel project: welfare implications of changes in production systems for laying hens. World’s Poultry Science Journal 63, 101–114.
The LayWel project: welfare implications of changes in production systems for laying hens.Crossref | GoogleScholarGoogle Scholar |

Blokhuis HJ, Van Der Haar JW (1989) Effects of floor type during rearing and of beak trimming on ground pecking and feather pecking in laying hens. Applied Animal Behaviour Science 22, 359–369.
Effects of floor type during rearing and of beak trimming on ground pecking and feather pecking in laying hens.Crossref | GoogleScholarGoogle Scholar |

Blokhuis HJ, Wiepkema PR (1998) Studies of feather pecking in poultry. The Veterinary Quarterly 20, 6–9.
Studies of feather pecking in poultry.Crossref | GoogleScholarGoogle Scholar | 9477526PubMed |

Blokhuis HJ, Van der Haar JW, Koole PG (1987) Effects of beak trimming and floor type on feed consumption and body weight of pullets during rearing. Poultry Science 66, 623–625.
Effects of beak trimming and floor type on feed consumption and body weight of pullets during rearing.Crossref | GoogleScholarGoogle Scholar | 3615323PubMed |

Bourke M, Glatz PC, Barnett JL, Critchley KL (2002a) Beak trimming training manual. Edn 1, Publication no. 02/092. (Rural Industries Research and Development Corporation: Canberra, ACT, Australia)

Bourke M, Glatz PC, Barnett JL, Critchley KL (2002b) Beak trimming trainer’s guidelines. Edn 1, Publication no. 02/093. (Rural Industries Research and Development Corporation: Canberra, ACT, Australia)

Breward J (1983) Cutaneous nociceptors in the chicken beak. The Journal of Physiology 346, 56P

Breward J, Gentle MJ (1985) Neuroma formation and abnormal afferent nerve discharges after partial beak amputation (beak trimming) in poultry. Experientia 41, 1132–1134.
Neuroma formation and abnormal afferent nerve discharges after partial beak amputation (beak trimming) in poultry.Crossref | GoogleScholarGoogle Scholar | 4043320PubMed |

Buitenhuis AJ, Rodenburg TB, Siweka M, Cornelissen SJB, Nieuwland MGB, Crooijmans RPMA, Groenen MAM, Koene P, Bovenhuisa JH, van der Poela J (2005) Quantitative trait loci for behavioural traits in chickens. Livestock Production Science 93, 95–103.
Quantitative trait loci for behavioural traits in chickens.Crossref | GoogleScholarGoogle Scholar |

Cain JR, Weber JM, Lockamy TA, Creger CR (1984) Grower diets and bird density effects on growth and cannibalism in ring-necked pheasants. Poultry Science 63, 450–457.
Grower diets and bird density effects on growth and cannibalism in ring-necked pheasants.Crossref | GoogleScholarGoogle Scholar | 6718298PubMed |

Carruthers CT, Gabrush T, Schwean-Lardner K, Knezacek TD, Classen HL, Bennett C (2012) On-farm survey of beak characteristics in White Leghorns as a result of hot blade trimming or IR beak treatment. Journal of Applied Poultry Research 21, 645–650.
On-farm survey of beak characteristics in White Leghorns as a result of hot blade trimming or IR beak treatment.Crossref | GoogleScholarGoogle Scholar |

Cheng H-W (2005) Acute and chronic pain in beak-trimmed chickens. In ‘Poultry welfare issues: beak trimming’. (Ed. PC Glatz) pp. 31–49. (Nottingham University Press: Nottingham, UK)

Choct M, Hartini S (2005) Alternatives to beak-trimming. 8.3. Interaction between nutrition and cannibalism in laying hens. In ‘Poultry welfare issues: beak trimming’. (Ed. PC Glatz) pp. 111–115. (Nottingham University Press: Nottingham, UK)

Craig JV, Lee HY (1989) Beak trimming and genetic stock effects on behaviour and mortality from cannibalism in White Leghorn-type pullets. Poultry Science 68, 1720–1723.
Beak trimming and genetic stock effects on behaviour and mortality from cannibalism in White Leghorn-type pullets.Crossref | GoogleScholarGoogle Scholar |

Craig JV, Muir WM (1991) Research note: genetic adaptation to multiple-bird cage environment with effective beak trimming. Poultry Science 70, 2214–2217.
Research note: genetic adaptation to multiple-bird cage environment with effective beak trimming.Crossref | GoogleScholarGoogle Scholar | 1956864PubMed |

Craig JV, Muir WM (1996) Group selection for adaptation to multiple-hen cages: beak-related mortality, feathering, and body weight responses. Poultry Science 75, 294–302.
Group selection for adaptation to multiple-hen cages: beak-related mortality, feathering, and body weight responses.Crossref | GoogleScholarGoogle Scholar | 8778719PubMed |

Craig JV, Craig JA, Milliken GA (1992) Beak trimming effects on beak length and feed usage for growth and egg production. Poultry Science 71, 1830–1841.
Beak trimming effects on beak length and feed usage for growth and egg production.Crossref | GoogleScholarGoogle Scholar | 1437970PubMed |

Cronin GM, Glatz PC (2020) Causes of feather pecking and subsequent welfare issues for the laying hen: a review. Animal Production Science.
Causes of feather pecking and subsequent welfare issues for the laying hen: a review.Crossref | GoogleScholarGoogle Scholar |

Cronin GM, Hopcroft RL, Groves PJ, Hall EJS, Phalen DN, Hemsworth PH (2018) Why did severe feather pecking and cannibalism outbreaks occur? An unintended case study from a factorial experiment investigating the effects of providing straw to, and imposing stress on pullets reared for free-range egg production. Poultry Science 97, 1484–1502.
Why did severe feather pecking and cannibalism outbreaks occur? An unintended case study from a factorial experiment investigating the effects of providing straw to, and imposing stress on pullets reared for free-range egg production.Crossref | GoogleScholarGoogle Scholar | 29462494PubMed |

Damme K, Urselmans S (2013) IR beak treatment: a temporary solution? Lohmann Information 48, 36–44.

Davis GS, Anderson KE, Jones DR (2004) The effects of different beak trimming techniques on plasma corticosterone and performance criteria in Single Comb White Leghorn hens. Poultry Science 83, 1624–1628.
The effects of different beak trimming techniques on plasma corticosterone and performance criteria in Single Comb White Leghorn hens.Crossref | GoogleScholarGoogle Scholar | 15510544PubMed |

de Haas EN, van der Eijk JAJ (2018) Where in the serotonergic system does it go wrong? Unravelling the route by which the serotonergic system affects feather pecking in chickens. Neuroscience and Biobehavioral Reviews 95, 170–188.
Where in the serotonergic system does it go wrong? Unravelling the route by which the serotonergic system affects feather pecking in chickens.Crossref | GoogleScholarGoogle Scholar | 30055196PubMed |

de Jong IC, Gunnink H, Rommers JM, Bracke MBM (2013) Effect of substrate during early rearing on floor and feather pecking behaviour in young and adult laying hens. Archiv für Geflügelkunde 77, 15–22.

deKoning C, Kitessa SM, Barekatain R, Drake K (2018) Determination of range enrichment for improved hen welfare on commercial fixed-range free-range layer farms. Animal Production Science 59, 1336–1348.
Determination of range enrichment for improved hen welfare on commercial fixed-range free-range layer farms.Crossref | GoogleScholarGoogle Scholar |

Dennis RL, Cheng HW (2010) A comparison of IR and hot-blade beak trimming in laying hens. International Journal of Poultry Science 9, 716–719.
A comparison of IR and hot-blade beak trimming in laying hens.Crossref | GoogleScholarGoogle Scholar |

Dennis RL, Cheng HW (2012) Effects of different IR beak treatment protocols on chicken welfare and physiology. Poultry Science 91, 1499–1505.
Effects of different IR beak treatment protocols on chicken welfare and physiology.Crossref | GoogleScholarGoogle Scholar | 22700492PubMed |

Dennis RL, Fahey AG, Cheng HW (2009) Infrared beak treatment method compared with conventional hot-blade trimming in laying hens. Poultry Science 88, 38–43.

Devor M, Rappaport ZH (1990) Pain and the pathophysiology of damaged nerves. In ‘Pain syndromes in neurology’. (Ed. H Fields) pp. 47–83. (Butterworths: London, UK)

Dixon G, Nicol CJ (2008) The effect of diet change on the behaviour of layer pullets. Animal Welfare 17, 101–109.

Dixon LM, Duncan IJH, Mason GJH (2010) The effects of four types of enrichment on feather-pecking behaviour in laying hens housed in barren environments. Animal Welfare 19, 429–435.

Duncan IJH, Slee GS, Seawright E, Breward J (1989) Behavioural consequences of partial beak amputation (beak-trimming) in poultry. British Poultry Science 30, 479–488.
Behavioural consequences of partial beak amputation (beak-trimming) in poultry.Crossref | GoogleScholarGoogle Scholar |

Elgar MA (1989) Predator vigilance and group size in mammals and birds: a critical review of empirical evidence. Biological Reviews of the Cambridge Philosophical Society 64, 13–33.
Predator vigilance and group size in mammals and birds: a critical review of empirical evidence.Crossref | GoogleScholarGoogle Scholar | 2655726PubMed |

Elwinger K, Tufvesson M, Lagerkvist G, Tauson R (2008) Feeding layers of different genotypes in organic feed environments. British Poultry Science 49, 654–665.
Feeding layers of different genotypes in organic feed environments.Crossref | GoogleScholarGoogle Scholar | 19093238PubMed |

Fiks-van Niekerk TGCM, Elson A (2005) Alternatives to beak-trimming. 8.6. Abrasive devices to blunt the beak tip. In ‘Poultry welfare issues: beak trimming’. (Ed. PC Glatz) pp. 127–131. (Nottingham University Press: Nottingham, UK)

Freire R, Glatz PC, Hinch G (2008) Self-administration of an analgesic does not alleviate pain in beak trimmed chickens. Asian–Australasian Journal of Animal Sciences 21, 443–448.
Self-administration of an analgesic does not alleviate pain in beak trimmed chickens.Crossref | GoogleScholarGoogle Scholar |

Gabrush T (2011) Effects of the degree of beak trimming on the performance of White Leghorns. MSc Thesis, University of Saskatchewan, Saskatoon, Canada.

Gentle MJ (1979) Sensory control of food intake. In ‘Food intake regulation in poultry’. (Ed. BM Freedman) pp. 259–273. (British Poultry Science: Edinburgh, UK)

Gentle MJ (1986a) Neuroma formation following partial beak amputation (beak trimming) in the chicken. Research in Veterinary Science 41, 383–385.
Neuroma formation following partial beak amputation (beak trimming) in the chicken.Crossref | GoogleScholarGoogle Scholar | 3809730PubMed |

Gentle MJ (1986b) Beak trimming in poultry. World’s Poultry Science Journal 42, 268–275.
Beak trimming in poultry.Crossref | GoogleScholarGoogle Scholar |

Gentle MJ (1989) Cutaneous sensory afferents recorded from the nervus intramandibularis in Gallus gallus var. domesticus. Journal of Comparative Physiology 164, 763–774.
Cutaneous sensory afferents recorded from the nervus intramandibularis in Gallus gallus var. domesticus.Crossref | GoogleScholarGoogle Scholar | 2724186PubMed |

Gentle MJ (1991) The acute effects of amputation on peripheral trigeminal afferents in Gallus gallus var. domesticus. Pain 46, 97–103.
The acute effects of amputation on peripheral trigeminal afferents in Gallus gallus var. domesticus.Crossref | GoogleScholarGoogle Scholar | 1896214PubMed |

Gentle MJ (1992) Pain in birds. Animal Welfare 1, 235–247.

Gentle MJ (1998) Welfare aspects of beak trimming in poultry. In ‘Proceedings of the 10th Australian Poultry Science Association conference’. (Ed. D Balnave) pp. 56–64. (The University of Sydney: Sydney, NSW, Australia)

Gentle MJ, Breward J (1986) The bill tip organ of the chicken (Gallus gallus var. domesticus). Journal of Anatomy 145, 79–85.

Gentle MJ, Hunter LN (1991) Physiological and behavioural responses associated with feather removal in Gallus gallus var. domesticus. Research in Veterinary Science 50, 95–101.
Physiological and behavioural responses associated with feather removal in Gallus gallus var. domesticus.Crossref | GoogleScholarGoogle Scholar | 2047598PubMed |

Gentle MJ, McKeegan DEF (2007) Evaluation of the effects of IR beak trimming in broiler breeder chicks. The Veterinary Record 160, 145–148.
Evaluation of the effects of IR beak trimming in broiler breeder chicks.Crossref | GoogleScholarGoogle Scholar | 17277295PubMed |

Gentle MJ, Hughes BO, Hubrecht RC (1982) The effect of beak trimming on food intake, feeding behaviour and body weight in adult hens. Applied Animal Ethology 8, 147–159.
The effect of beak trimming on food intake, feeding behaviour and body weight in adult hens.Crossref | GoogleScholarGoogle Scholar |

Gentle MJ, Waddington D, Hunter LN, Jones RB (1990) Behavioural evidence for persistent pain following partial beak amputation in the chicken. Applied Animal Behaviour Science 27, 149–157.
Behavioural evidence for persistent pain following partial beak amputation in the chicken.Crossref | GoogleScholarGoogle Scholar |

Gentle MJ, Hughes BO, Fox A, Waddington D (1997) Behavioural and anatomical consequences of two beak trimming methods in 1- and 10-day old chicks. British Poultry Science 38, 453–463.
Behavioural and anatomical consequences of two beak trimming methods in 1- and 10-day old chicks.Crossref | GoogleScholarGoogle Scholar | 9510987PubMed |

Glatz PC (1987) Effects of beak trimming and restraint on heart rate, food intake, body weight and egg production in hens. British Poultry Science 28, 601–611.
Effects of beak trimming and restraint on heart rate, food intake, body weight and egg production in hens.Crossref | GoogleScholarGoogle Scholar | 3446331PubMed |

Glatz PC (1990) Effect of age of beak trimming on the production performance of hens. Australian Journal of Experimental Agriculture 30, 349–355.
Effect of age of beak trimming on the production performance of hens.Crossref | GoogleScholarGoogle Scholar |

Glatz PC (2000) Beak trimming methods-a review. Asian–Australasian Journal of Animal Sciences 13, 1619–1637.
Beak trimming methods-a review.Crossref | GoogleScholarGoogle Scholar |

Glatz PC (2002) Growth of beaks in layers following trimming. International Journal of Poultry Science 1, 158–160.
Growth of beaks in layers following trimming.Crossref | GoogleScholarGoogle Scholar |

Glatz PC (2003) The effects of beak length and condition on food intake and feeding behaviour of hens. International Journal of Poultry Science 2, 53–57.
The effects of beak length and condition on food intake and feeding behaviour of hens.Crossref | GoogleScholarGoogle Scholar |

Glatz PC (2004) Laser beak trimming: a report for the Australian Egg Corporation. AECL, Sydney, NSW, Australia.

Glatz PC (2005a) What is beak trimming and why are birds trimmed? In ‘Poultry welfare issues: beak trimming’. (Ed. PC Glatz) pp. 1–18. (Nottingham University Press: Nottingham, UK)

Glatz PC (2005b) Bird health and handling issues associated with beak trimming. In ‘Poultry welfare issues: beak trimming’. (Ed. PC Glatz) pp. 87–92. (Nottingham University Press: Nottingham, UK)

Glatz PC (2005c) Alternatives to beak trimming. 8.7. Use of fitted devices and stock wound sprays. In ‘Poultry welfare issues: beak trimming’. (Ed. PC Glatz) pp. 133–136. (Nottingham University Press: Nottingham, UK)

Glatz PC, Bourke M (2006) ‘Beak trimming handbook for egg producers. Best practice for minimising cannibalism in poultry.’ (Landlinks Press: Melbourne, Vic., Australia)

Glatz PC, Frensham AB (1987) Effects of relocation on production in caged layers. British Poultry Science 28, 119–128.
Effects of relocation on production in caged layers.Crossref | GoogleScholarGoogle Scholar |

Glatz PC, Hinch GN (2008) Minimise cannibalism using innovative beak trimming methods. Australian Poultry CRC. Final report Project no. 04-20. (Australian Poultry CRC: Armidale, NSW, Australia)

Glatz PC, Lunam CA (1994) Production and heart rate responses of chickens beak-trimmed at hatch or at 10 or at 42 days of age. Australian Journal of Experimental Agriculture 34, 443–449.
Production and heart rate responses of chickens beak-trimmed at hatch or at 10 or at 42 days of age.Crossref | GoogleScholarGoogle Scholar |

Glatz P, Runge G (2017) ‘Managing fowl behaviour. A best practice guide to help egg producers and poultry breeders manage feather pecking and cannibalism in their flocks.’ (Australian Egg Corporation: Sydney, NSW, Australia)

Glatz PC, Murphy LB, Preston AP (1992) Analgesic therapy of beak-trimmed chickens. Australian Veterinary Journal 69, 18
Analgesic therapy of beak-trimmed chickens.Crossref | GoogleScholarGoogle Scholar | 1554338PubMed |

Glatz PC, Lunam CA, Barnett JL (1998) Feeding behaviour of 10-week-old pullets following beak trimming at hatch. In ‘Proceedings of the 10th Australian Poultry Science Association conference’. (Ed. D Balnave) p. 132. (The University of Sydney: Sydney, NSW, Australia)

Glatz P, Hinch G, Nagle T (2010) Alternatives to beak trimming. Australian Poultry CRC. Final report Project no. 07-17. Australian Poultry CRC, Armidale, NSW, Australia.

Gleaves EW (1984) ‘Cannibalism. Cause and prevention in poultry.’ Available at http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=2280&context=extensionhist [Verified 22 April 2019]

Gottschaldt KM (1985) Structure and function of avian somatosensory receptors. In ‘Form and function in birds. Vol 3’. (Ed. AS King, J McLelland) pp. 375–461. (Academic Press: London, UK)

Gregory NG (1998) Decision-making on ethical issues. Vetscript 11, 21

Gregory NG (2005) Ethics of beak-trimming and cannibalism. In ‘Poultry welfare issues: beak trimming’. (Ed. PC Glatz) pp. 19–29. (Nottingham University Press: Nottingham, UK)

Gross WB, Siegel HS (1983) Evaluation of the heterophil/lymphocyte ratio as a measure of stress in chickens. Avian Diseases 27, 972–979.
Evaluation of the heterophil/lymphocyte ratio as a measure of stress in chickens.Crossref | GoogleScholarGoogle Scholar | 6360120PubMed |

Guesdon V, Ahmed AMH, Mallet S, Faure JM, Nys Y (2006) Effects of beak trimming and cage design on laying hen performance and egg quality. British Poultry Science 47, 1–12.
Effects of beak trimming and cage design on laying hen performance and egg quality.Crossref | GoogleScholarGoogle Scholar | 16546790PubMed |

Gunnarsson S, Keeling LJ, Svedberg J (1999) Effect of rearing factors on the prevalence of floor eggs, cloacal cannibalism and feather pecking in commercial flocks of loose housed laying hens. British Poultry Science 40, 12–18.
Effect of rearing factors on the prevalence of floor eggs, cloacal cannibalism and feather pecking in commercial flocks of loose housed laying hens.Crossref | GoogleScholarGoogle Scholar | 10405030PubMed |

Gustafson LA, Cheng HW, Garner TP, Pajor EA, Mench JA (2007) Effects of bill-trimming Muscovy ducks on behavior, body weight gain, and bill morphopathology. Applied Animal Behaviour Science 103, 59–74.
Effects of bill-trimming Muscovy ducks on behavior, body weight gain, and bill morphopathology.Crossref | GoogleScholarGoogle Scholar |

Harlander-Matauschek A, Rodenburg TB (2011) Applying chemical stimuli on feathers to reduce feather pecking in laying hens. Applied Animal Behaviour Science 132, 146–151.
Applying chemical stimuli on feathers to reduce feather pecking in laying hens.Crossref | GoogleScholarGoogle Scholar |

Harlander-Matauschek A, Beck P, Piepho HP (2009) Taste aversion learning to eliminate feather pecking in laying hens, Gallus domesticus. Animal Behaviour 78, 485–490.
Taste aversion learning to eliminate feather pecking in laying hens, Gallus domesticus.Crossref | GoogleScholarGoogle Scholar |

Harrison PC, Bercovitz AB, Leary GA (1968) Development of eye enlargement of domestic fowl subjected to low intensity light. International Journal of Biometeorology 12, 351–358.
Development of eye enlargement of domestic fowl subjected to low intensity light.Crossref | GoogleScholarGoogle Scholar | 5728673PubMed |

Hartcher KM, Tran KTN, Wilkinson SJ, Hemsworth PH, Thomson PC, Cronin GM (2015a) The effects of environmental enrichment and beak-trimming during the rearing period on subsequent feather damage due to feather-pecking in laying hens. Poultry Science 94, 852–859.
The effects of environmental enrichment and beak-trimming during the rearing period on subsequent feather damage due to feather-pecking in laying hens.Crossref | GoogleScholarGoogle Scholar | 25717088PubMed |

Hartcher KM, Tran KTN, Wilkinson SJ, Hemsworth PH, Thomson PC, Cronin GM (2015b) The effects of rearing treatments, beak-trimming and environmental enrichment, on the reaction to novelty during rearing and feather damage in adulthood in free range laying hens. Applied Animal Behaviour Science 164, 64–72.
The effects of rearing treatments, beak-trimming and environmental enrichment, on the reaction to novelty during rearing and feather damage in adulthood in free range laying hens.Crossref | GoogleScholarGoogle Scholar |

Hausberger M (1992a) Visual pecking preferences in domestic chicks. Part I. Responses of different breeds of chicks to different sorts of seeds. Academie des Science 314, 273–278.

Hausberger M (1992b) Visual pecking preferences in domestic chicks. Part II. Responses of different breeds of chicks to different sorts of seeds. Academie des Science 314, 331–335.

Hegelund L, Kjaer S, Kristensen IS, Sorensen ST (2002) Use of the outdoor area by hens in commercial organic egg production systems. Effect of climate factors and cover. Eleventh European Poultry Conference-Abstracts. Archiv für Geflügelkunde 66, 141–142.

Hemsworth PH, Mellor DJ, Cronin GM, Tilbrook AJ (2015) Scientific assessment of animal welfare. New Zealand Veterinary Journal 63, 24–30.
Scientific assessment of animal welfare.Crossref | GoogleScholarGoogle Scholar | 25263963PubMed |

Hester PY (2005) Production responses of beak-trimmed birds. In ‘Poultry welfare issues: beak trimming’. (Ed. PC Glatz) pp. 79–86. (Nottingham University Press: Nottingham, UK)

Hester PY, Shea-Moore M (2003) Beak trimming egg-laying strains of chickens. World’s Poultry Science Journal 59, 458–474.
Beak trimming egg-laying strains of chickens.Crossref | GoogleScholarGoogle Scholar |

Hinch GN, Nolan JV, Walkden-Brown S, Thomson E (1997) Interactions between the immune system and food choice in cockerels. Recent Advances in Animal Nutrition in Australia 12, 249

Honaker CF, Ruszler PL (2004) The effect of claw and beak reduction on growth parameters and fearfulness of two Leghorn strains. Poultry Science 83, 873–881.
The effect of claw and beak reduction on growth parameters and fearfulness of two Leghorn strains.Crossref | GoogleScholarGoogle Scholar | 15206612PubMed |

Icken W, Cavero D, Schmutz M (2017) Selection on beak shape to reduce feather pecking in laying hens. Lohman Information 51, 22–27.

Iffland H, Wellmann R, Schmid M, Preu S, Tetens J, Bessei W, Bennewitz J (2020) Genomewide mapping of selection signatures and genes for extreme feather pecking in two divergently selected laying hen lines. Animals 10, 262–280.
Genomewide mapping of selection signatures and genes for extreme feather pecking in two divergently selected laying hen lines.Crossref | GoogleScholarGoogle Scholar |

Johnsen PF, Vestergaard KS, Norgaard-Nielsen G (1998) Influence of early rearing conditions on the development of feather pecking and cannibalism in domestic fowl. Applied Animal Behaviour Science 60, 25–41.
Influence of early rearing conditions on the development of feather pecking and cannibalism in domestic fowl.Crossref | GoogleScholarGoogle Scholar |

Jones RB (2002) Role of comparative psychology in the development of effective environmental enrichment strategies to improve poultry welfare. International Journal of Comparative Psychology 15, 77–106.

Jones RB (2005) Alternatives to beak-trimming. 8.1. Environmental enrichment can reduce feather pecking. In ‘Poultry welfare issues: beak trimming’. (Ed. PC Glatz) pp. 93–97. (Nottingham University Press: Nottingham, UK)

Jones RB, Carmichael NL, Rayner E (2000) Pecking preferences and pre-dispositions in domestic chicks: implications for the development of environmental enrichment devices. Applied Animal Behaviour Science 69, 291–312.
Pecking preferences and pre-dispositions in domestic chicks: implications for the development of environmental enrichment devices.Crossref | GoogleScholarGoogle Scholar | 10915915PubMed |

Jongman EC, Glatz PC, Barnett JL (2008) Changes in behaviour of laying hens following beak trimming at hatch and re-trimming at 14 weeks. Asian–Australasian Journal of Animal Sciences 21, 291–298.
Changes in behaviour of laying hens following beak trimming at hatch and re-trimming at 14 weeks.Crossref | GoogleScholarGoogle Scholar |

Jung L, Knierim U (2018) Are practice recommendations for the prevention of feather pecking in laying hens in non-cage systems in line with the results of experimental and epidemiological studies? Applied Animal Behaviour Science 200, 1–12.
Are practice recommendations for the prevention of feather pecking in laying hens in non-cage systems in line with the results of experimental and epidemiological studies?Crossref | GoogleScholarGoogle Scholar |

Kajlich AS, Shivaprasad HL, Trampel DW, Hill AE, Parsons RL, Millman ST, Mench JA (2016) Incidence, severity, and welfare implications of lesions observed postmortem in laying hens from commercial noncage farms in California and Iowa. Avian Diseases 60, 8–15.
Incidence, severity, and welfare implications of lesions observed postmortem in laying hens from commercial noncage farms in California and Iowa.Crossref | GoogleScholarGoogle Scholar | 26953938PubMed |

Keeling L, Andersson L, Schütz KE, Kerje S, Fredriksson R, Carlborg O, Cornwallis CK, Pizzari T, Jensen P (2004) A genetic factor that encourages a form of farmyard bullying has been identified. Nature 431, 645–646.
A genetic factor that encourages a form of farmyard bullying has been identified.Crossref | GoogleScholarGoogle Scholar | 15470416PubMed |

Kjaer JB (2005) Alternatives to beak-trimming. 8.2. Genetics. In ‘Poultry welfare issues: beak trimming’. (Ed. PC Glatz) pp. 101–109. (Nottingham University Press: Nottingham, UK)

Kjaer JB, Sorensen P (1997) Feather pecking behaviour in White Leghorns, a genetic study. British Poultry Science 38, 333–341.
Feather pecking behaviour in White Leghorns, a genetic study.Crossref | GoogleScholarGoogle Scholar | 9347139PubMed |

Kjaer JB, Vestergaard KS (1999) Development of feather pecking in relation to light intensity. Applied Animal Behaviour Science 62, 243–254.
Development of feather pecking in relation to light intensity.Crossref | GoogleScholarGoogle Scholar |

Kjaer JB, Sorensen P, Su G (2001) Divergent selection on feather pecking behaviour in laying hens (Gallus gallus domesticus). Applied Animal Behaviour Science 71, 229–239.
Divergent selection on feather pecking behaviour in laying hens (Gallus gallus domesticus).Crossref | GoogleScholarGoogle Scholar | 11230903PubMed |

Kuenzel WJ (2007) Neurobiological basics of sensory perception: welfare implications of beak trimming. Poultry Science 86, 1273–1282.
Neurobiological basics of sensory perception: welfare implications of beak trimming.Crossref | GoogleScholarGoogle Scholar | 17495105PubMed |

Lee HY, Craig JV (1990) Beak trimming effects on the behavior and weight gain of floor-reared, egg-strain pullets from three genetic stocks during the rearing period. Poultry Science 69, 568–575.
Beak trimming effects on the behavior and weight gain of floor-reared, egg-strain pullets from three genetic stocks during the rearing period.Crossref | GoogleScholarGoogle Scholar |

Lunam CA (2005) The anatomy and innervation of the chicken beak: effects of trimming and retrimming. In ‘Poultry welfare issues: beak trimming’. (Ed. PC Glatz) pp. 51–68. (Nottingham University Press: Nottingham, UK)

Lunam CA, Glatz PC (1992) Substance P-immuno-reactive nerve fibres in the chicken beak. In ‘Proceedings of the 4th Australian Poultry Science Association conference’. (Ed. D Balnave) p. 145. (The University of Sydney: Sydney, NSW, Australia)

Lunam CA, Glatz PC (1993a) Sensory nerves within the beak of the domestic fowl; their contribution to behaviour after beak trimming. In ‘Proceedings of the 5th Australian Poultry Science Association conference’. (Ed. D Balnave) pp. 49–52. (The University of Sydney: Sydney, NSW, Australia)

Lunam CA, Glatz PC (1993b) Taste buds of the domestic fowl are innervated by nerve fibres immune-reactive for calbindin but not for substance P. In ‘Proceedings of the 1993 Australian neuroscience meeting. Vol. 4’. (Ed. Anon.) p. 115. Australian Neuroscience Society (Melbourne, Vic., Australia)

Lunam CA, Glatz PC (1995) Substance P and calcitonin gene-related peptide in the upper beak of the chicken with particular reference to the salivary glands. In ‘Proceedings of the 7th Australian Poultry Science Association conference’. (Ed. D Balnave) pp. 176–179. (The University of Sydney: Sydney, NSW, Australia)

Lunam CA, Glatz PC, Hsu YJ (1996) The absence of neuromas in beaks of adult hens following conservative trimming at hatch. Australian Veterinary Journal 74, 46–49.
The absence of neuromas in beaks of adult hens following conservative trimming at hatch.Crossref | GoogleScholarGoogle Scholar | 8894005PubMed |

Marchant-Forde RM, Cheng HW (2010) Different effects of IR and one-half hot-blade beak trimming on beak topography and growth. Poultry Science 89, 2559–2564.
Different effects of IR and one-half hot-blade beak trimming on beak topography and growth.Crossref | GoogleScholarGoogle Scholar | 21076092PubMed |

Marchant-Forde RM, Fahey AG, Cheng HW (2008) Comparative effects of IR and one-third hot-blade trimming on beak topography, behavior and growth. Poultry Science 87, 1474–1483.
Comparative effects of IR and one-third hot-blade trimming on beak topography, behavior and growth.Crossref | GoogleScholarGoogle Scholar | 18648038PubMed |

Matauschek AH, Beck P, Rodenburg TB (2010) Effect of an early bitter taste experience on subsequent feather-pecking behaviour in laying hens. Applied Animal Behaviour Science 127, 108–114.
Effect of an early bitter taste experience on subsequent feather-pecking behaviour in laying hens.Crossref | GoogleScholarGoogle Scholar |

McAdie TM, Keeling LJ, Blokhuis HJ, Jones RB (2005) Reduction in feather pecking and improvement of feather condition with the presentation of a string device to chickens. Applied Animal Behaviour Science 93, 67–80.
Reduction in feather pecking and improvement of feather condition with the presentation of a string device to chickens.Crossref | GoogleScholarGoogle Scholar |

McKeegan (2016) Beak trimming of laying hens. Welfare costs and benefits. In ‘Achieving sustainable production of eggs. Vol. 2. Animal welfare and sustainability’. (Ed. J Roberts) pp. 125–139. (Burleigh Dodds Science Publishing: Cambridge, UK)

McKeegan DEF, Philbey AW (2012) Chronic neurophysiological and anatomical changes associated with IR beak treatment and their implications for laying hen welfare. Animal Welfare 21, 207–217.
Chronic neurophysiological and anatomical changes associated with IR beak treatment and their implications for laying hen welfare.Crossref | GoogleScholarGoogle Scholar |

Miao ZH, Glatz PC, Ru YJ, Wyatt SC, Rodda BK (2006) Integration of hens into a crop and pasture rotation system in Australia: production and agronomic aspects. In ‘Proceedings of the 18th Australian Poultry Science Association conference’. (Ed. J Roberts) pp. 94–99. (The University of Sydney: Sydney, NSW, Australia)

Nagle T, Glatz PC (2012) Free range hens use the range more when the outdoor environment is enriched. Asian–Australasian Journal of Animal Sciences 25, 584–591.
Free range hens use the range more when the outdoor environment is enriched.Crossref | GoogleScholarGoogle Scholar | 25049600PubMed |

Newberry RC (2004) Cannibalism. ‘In welfare of the laying hen’. (Ed. GC Perry) pp. 239–258. (CABI Publishing: Wallingford, UK)

Newberry RC, Keeling LJ, Estevez I, Bilcik B (2007) Behaviour when young as a predictor of severe feather pecking in adult laying hens: the redirected foraging hypothesis revisited. Applied Animal Behaviour Science 107, 262–274.
Behaviour when young as a predictor of severe feather pecking in adult laying hens: the redirected foraging hypothesis revisited.Crossref | GoogleScholarGoogle Scholar |

Nicol CJ, Lindberg AC, Phillips AJ, Pope SJ, Wilkins LJ, Green LE (2001) Influence of prior exposure to wood shavings on feather pecking, dustbathing and foraging in adult laying hens. Applied Animal Behaviour Science 73, 141–155.
Influence of prior exposure to wood shavings on feather pecking, dustbathing and foraging in adult laying hens.Crossref | GoogleScholarGoogle Scholar | 11358611PubMed |

Nicol CJ, Bestman M, Gilani A-M, De Haas EN, De Jong IC, Lambton S, Wagenaar JP, Weeks CA, Rodenburg TB (2013) The prevention and control of feather pecking: application to commercial systems. World’s Poultry Science Journal 69, 775–788.
The prevention and control of feather pecking: application to commercial systems.Crossref | GoogleScholarGoogle Scholar |

Nicol CJ, Bouwsema J, Caplen G, Davies AC, Hockenhull J, Lambton SL, Lines JA, Mullan S, Weeks CA (2017) ‘Farmed bird welfare science review.’ (Department of Economic Development, Jobs, Transport and Resources: Melbourne, Vic., Australia)

Nolte DL, Farley JP, Campbell DL, Epple GM, Mason JR (1993) Potential repellents to prevent mountain beaver damage. Crop Protection 12, 624–626.
Potential repellents to prevent mountain beaver damage.Crossref | GoogleScholarGoogle Scholar |

Nolte DL, Mason JR, Epple GM, Aronov E, Campbell DL (1994) Why are predator urines aversive to prey? Journal of Chemical Ecology 20, 1505–1516.
Why are predator urines aversive to prey?Crossref | GoogleScholarGoogle Scholar | 24242647PubMed |

Parkinson G (2005) Alternatives to beak-trimming. 8.4. Light intensity. In ‘Poultry welfare issues: beak trimming’. (Ed. PC Glatz) pp. 117–122. (Nottingham University Press: Nottingham, UK)

Petek M, Topal E, Cavusoglu E (2015) Effects of age at first access to range area on pecking behaviour and plumage quality of free-range layer chickens. Archiv Fur Tierzucht: Archives of Animal Breeding 58, 85–91.
Effects of age at first access to range area on pecking behaviour and plumage quality of free-range layer chickens.Crossref | GoogleScholarGoogle Scholar |

Pötzsch CJ, Lewis K, Nicol CJ, Green LE (2001) A cross-sectional study of the prevalence of vent pecking in laying hens in alternative systems and its associations with feather pecking, management and disease. Applied Animal Behaviour Science 74, 259–272.
A cross-sectional study of the prevalence of vent pecking in laying hens in alternative systems and its associations with feather pecking, management and disease.Crossref | GoogleScholarGoogle Scholar |

Primary Industries Standing Committee (2002) ‘Model code of practice for the welfare of animals: domestic poultry.’ 4th edn. SCARM report 83. (CSIRO Publishing: Melbourne, Australia)

Provenza FD (1996) Acquired aversions as the basis for varied diets of ruminants foraging on rangelands. Journal of Animal Science 74, 2010–2020.
Acquired aversions as the basis for varied diets of ruminants foraging on rangelands.Crossref | GoogleScholarGoogle Scholar | 8856457PubMed |

Raginski C, K., Schwean-Lardner K, Gomis S, Classen HL (2014) The impact of various configurations of infrared beak treatment equipment on two white- and two brown-egg strains of hens: beak characteristics and pullet growth. Poultry Science 93, 74

Ralph CR, Tilbrook AJ (2016) The usefulness of measuring glucocorticoids for assessing animal welfare. Journal of Animal Science 94, 457–470.
The usefulness of measuring glucocorticoids for assessing animal welfare.Crossref | GoogleScholarGoogle Scholar | 27065116PubMed |

Rault J-L, Van de wouw A, Hemsworth P (2013) Fly the coop! Vertical structures influence the distribution and behaviour of laying hens in an outdoor range. In ‘Proceedings of the 24th Australian Poultry Science Association conference’. (Ed. J Roberts) p. 247. (The University of Sydney: Sydney, NSW, Australia)

Reed HJ, Wilkins LJ, Austin SD, Gregory NG (1993) The effect of environmental enrichment during rearing on fear reactions and depopulation trauma in adult caged hens. Applied Animal Behaviour Science 36, 39–46.
The effect of environmental enrichment during rearing on fear reactions and depopulation trauma in adult caged hens.Crossref | GoogleScholarGoogle Scholar |

Renz KG, Walkden-Brown SW (2007) Environmental enrichment strategies. In ‘Proceedings of the 19th Australian Poultry Science Association conference’. (Ed. R Pym) pp. 94–99. (The University of Sydney: Sydney, NSW, Australia)

Rodenburg TB, van Hierden YM, Buitenhuis J, Riedstrad B, Koenea P, Korteb SM, van der Poel JJ, Groothuis TGG, Blokhuis HJ (2004) Feather pecking in laying hens: new insights and directions for research? Applied Animal Behaviour Science 86, 291–298.
Feather pecking in laying hens: new insights and directions for research?Crossref | GoogleScholarGoogle Scholar |

Rodenburg TB, van Krimpen MM, de Jong IC, de Haas EN, Kops MS, Riedstra BJ, Nordquist RE, Wagenaar JP, Bestman M, Nicol CJ (2013) The prevention and control of feather pecking in laying hens: identifying the underlying principles. World’s Poultry Science Journal 69, 361–373.
The prevention and control of feather pecking in laying hens: identifying the underlying principles.Crossref | GoogleScholarGoogle Scholar |

Rooijen JV, Haar JVD (1997) Comparison of laser trimming with traditional beak trimming at day 1 and week 6. In ‘5th European symposium on poultry welfare’. (Eds P Koene, HJ Blokhuis) pp. 141–142. (Wageningen University: Wageningen, The Netherlands)

Runge GA, Glatz PC (2019) Use of best practice hot blade trimming when IR beak treatment is not available. In ‘Proceedings of the 30th Australian Poultry Science Association conference’. (Ed. J Roberts) pp. 151–154. (The University of Sydney: Sydney, NSW, Australia)

Sandilands V, Savory CJ (2002) Ontogeny of behavior in intact and beak trimmed layer pullets, with special reference to preening. British Poultry Science 43, 182–189.
Ontogeny of behavior in intact and beak trimmed layer pullets, with special reference to preening.Crossref | GoogleScholarGoogle Scholar | 12047080PubMed |

Schmidt M, Stracke J, Kulke K, Kemper N, Birgit Spindler B (2019) Case study of an automatic enrichment device for laying hens on a free-range laying hen farm. Agriculture 9, 91
Case study of an automatic enrichment device for laying hens on a free-range laying hen farm.Crossref | GoogleScholarGoogle Scholar |

Schwean-Lardner K, Classen HL, Raginski C, Gomis S (2014a) The impact of various configurations of the infrared beak treatment equipment on two white- and two brown-egg strains: behavior. Poultry Science 93, 74

Schwean-Lardner K, Classen HL, Raginski C, Gomis S (2014b) The impact of various configurations of infrared beak treatment equipment on two white- and two brown-egg strains of hens: performance. Poultry Science 93, 74

Schwean-Lardner K, Annett-Christianson CB, Rajendram J, Classen HL (2016) Does age of hot-blade trimming impact the performance and welfare of 2 strains of White Leghorn hens? Journal of Applied Poultry Research 25, 547–560.
Does age of hot-blade trimming impact the performance and welfare of 2 strains of White Leghorn hens?Crossref | GoogleScholarGoogle Scholar |

Shinmura T, Eguchi Y, Uetake K, Tanaka T (2006) Effects of light intensity and beak trimming on preventing aggression in laying hens. Animal Science Journal 77, 447–453.
Effects of light intensity and beak trimming on preventing aggression in laying hens.Crossref | GoogleScholarGoogle Scholar |

Singh M, Ruhnke I, de Koning C, Drake K, Skerman AG, Hinch GN, Glatz PC (2017) Demographics and practices of semi-intensive free-range farming systems in Australia with an outdoor stocking density of ≤1500 hens/hectare. PLoS One 12, e0187057
Demographics and practices of semi-intensive free-range farming systems in Australia with an outdoor stocking density of ≤1500 hens/hectare.Crossref | GoogleScholarGoogle Scholar | 29206228PubMed |

Speed MP (2000) Warning signals, receiver psychology and predator memory. Animal Behaviour 60, 269–278.
Warning signals, receiver psychology and predator memory.Crossref | GoogleScholarGoogle Scholar | 11007635PubMed |

Steenfeldt S, Kjaer JB, Engberg RM (2007) Effect of feeding silages or carrots as supplements to laying hens on production performance, nutrient digestibility, gut structure, gut microflora and feather pecking behaviour. British Poultry Science 48, 454–468.
Effect of feeding silages or carrots as supplements to laying hens on production performance, nutrient digestibility, gut structure, gut microflora and feather pecking behaviour.Crossref | GoogleScholarGoogle Scholar | 17701499PubMed |

Struthers S (2018) The impact of IR beak treatment on the production, behaviour, and welfare of layer pullets and hens. PhD Thesis, University of Saskatchewan, Saskatoon, Canada.

Struthers S, Gupta A, Gomis S, Herwig E, Schwean-Lardner K (2019) Understanding how IR beak treatment affects the beak tissue and the healing response of brown and white feathered layer pullets. Animals (Basel) 9, 665
Understanding how IR beak treatment affects the beak tissue and the healing response of brown and white feathered layer pullets.Crossref | GoogleScholarGoogle Scholar |

Suttie JW (1987) Recent advances in hepatic vitamin K metabolism and function. Hepatology 7, 367–376.
Recent advances in hepatic vitamin K metabolism and function.Crossref | GoogleScholarGoogle Scholar | 3549509PubMed |

Swenson GR, van Gulijk GHE (2014) The effect of water delivery on beak treated layer chicks. International Poultry Practice 28, 13–15.

Tauson R (1986) Avoiding excessive growth of claws in caged laying hens. Acta Agriculturae Scandinavica 36, 95–105.
Avoiding excessive growth of claws in caged laying hens.Crossref | GoogleScholarGoogle Scholar |

Tilbrook AJ, Ralph CR (2017) Neurophysiological assessment of animal welfare. Animal Production Science 57, 2370–2375.
Neurophysiological assessment of animal welfare.Crossref | GoogleScholarGoogle Scholar |

Tilbrook AJ, Ralph CR (2018) Hormones, stress and the welfare of animals. Animal Production Science 58, 408–415.
Hormones, stress and the welfare of animals.Crossref | GoogleScholarGoogle Scholar |

Tilbrook AJ, Barekatain R, Ralph CR (2018) Insights into assessment of the welfare of the laying hen in Australia. In ‘Proceedings of the 29th Australian Poultry Science Association conference’. (Ed. J Roberts) pp. 75–81. (The University of Sydney: Sydney, NSW, Australia)

Turner AI, Keating CL, Tilbrook AJ (2012) Sex differences and the role of sex steroids in sympatho-adrenal medullary system and hypothalamo–pituitary adrenal axis responses to stress. In ‘Sex steroids’. (Ed. SM Kahn) pp. 115–136. (InTech: Rijeka, Croatia)

van der Eijk JAJ, Lammers A, Kjaer JB, Rodenburg TB (2019) Stress response, peripheral serotonin and natural antibodies in feather pecking genotypes and phenotypes and their relation with coping style. Physiology & Behavior 199, 1–10.
Stress response, peripheral serotonin and natural antibodies in feather pecking genotypes and phenotypes and their relation with coping style.Crossref | GoogleScholarGoogle Scholar |

van Hierden YM, Korte SM, Ruesink EW, Van Reenen CG, Engel B, Koolhaas JM, Blokhuis HJ (2002) The development of feather pecking behaviour and targeting of pecking in chicks from a high and low feather pecking line of laying hens. Applied Animal Behaviour Science 77, 183–196.
The development of feather pecking behaviour and targeting of pecking in chicks from a high and low feather pecking line of laying hens.Crossref | GoogleScholarGoogle Scholar |

Van Krimpen MM, Kwakkel RP, Reuvekamp BFJ, van der Peet-Schwering CMC, Den Hartog LA, Verstegen MWA (2005) Impact of feeding management on feather pecking in laying hens. World’s Poultry Science Journal 61, 663–685.
Impact of feeding management on feather pecking in laying hens.Crossref | GoogleScholarGoogle Scholar |

van Liere P (1995) Responsiveness to a novel preening stimulus long after partial beak amputation (beak trimming) in laying hens. Behavioural Processes 34, 169–174.
Responsiveness to a novel preening stimulus long after partial beak amputation (beak trimming) in laying hens.Crossref | GoogleScholarGoogle Scholar |

Vieira Filho JA, Garcia AE, Oba E, dos Santos TA, Silva AP, Molino AB, Lima AP, Araújo Baldo GA (2016) Production index and quality of eggs of laying hens subjected to different methods of beak trimming. Pesquisa Agropecuária Brasileira 51, 759–765.
Production index and quality of eggs of laying hens subjected to different methods of beak trimming.Crossref | GoogleScholarGoogle Scholar |

Weeks CA, Lambton SL, Williams GA (2016) Implications for welfare, productivity and sustainability of the variation in reported levels of mortality for laying hen flocks kept in different housing systems: a meta-analysis of ten studies. PLoS One 11, e0146394
Implications for welfare, productivity and sustainability of the variation in reported levels of mortality for laying hen flocks kept in different housing systems: a meta-analysis of ten studies.Crossref | GoogleScholarGoogle Scholar | 26734933PubMed |

Weldon PJ, Graham DP, Mears LP (1993) Carnivore fecal chemicals suppress feeding by Alpine goats (Caprus hircus). Journal of Chemical Ecology 19, 2947–2952.
Carnivore fecal chemicals suppress feeding by Alpine goats (Caprus hircus).Crossref | GoogleScholarGoogle Scholar | 24248787PubMed |

Workman L, Rogers LJ (1990) Pecking preferences in young chicks: effects of nutritive reward and beak-trimming. Applied Animal Behaviour Science 26, 115–126.
Pecking preferences in young chicks: effects of nutritive reward and beak-trimming.Crossref | GoogleScholarGoogle Scholar |

Wurst M, Dekoning C (2020) ‘Pasture, tree and shrub selection and management on Australian rree range egg farms.’ (Australian Eggs: Sydney, NSW, Australia)

Zeltner E, Hirt H (2003) Effect of artificial structuring on the use of laying hen runs in a free-range system. British Poultry Science 44, 533–537.
Effect of artificial structuring on the use of laying hen runs in a free-range system.Crossref | GoogleScholarGoogle Scholar | 14584842PubMed |

Zhang S, Boa J (2008) Influence of early environmental experience on development of pecking behaviour in chicks. Dong Wu Xue Bao 54, 955–963.

Zimmerman P, Brown S, Glen E, Lindberg C, Pope S, Short F, Warriss P, Wilkins L, Nicol C (2005) The effects of stocking rate and modified management on the welfare of laying hens in non-cage systems. Animal Science Papers and Reports 23, 181–188.