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Food, fibre and pharmaceuticals from animals
REVIEW

Free-range laying hens: using technology to show the dynamics and impact of hen movement

I. Ruhnke A D , J. Boshoff B , I. V. Cristiani B , D. Schneider C , M. Welch C , T. Z. Sibanda A and M. Kolakshyapati A
+ Author Affiliations
- Author Affiliations

A School of Environmental and Rural Science, Faculty of Science, Agriculture, Business and Law, University of New England, Armidale, NSW 2351, Australia.

B CASI Data Transformation Hub, University of New England, Armidale, NSW 2351, Australia.

C School of Science and Technology, Precision Agriculture Research Group, University of New England, Armidale, NSW 2351, Australia.

D Corresponding author. Email: iruhnke@une.edu.au

Animal Production Science 59(11) 2046-2056 https://doi.org/10.1071/AN19256
Submitted: 29 April 2019  Accepted: 30 June 2019   Published: 16 September 2019

Abstract

Free-range laying hens are provided with the opportunity to access various structural areas, including open floor space, feed areas, water lines, next boxes, perches, aviary tiers, winter gardens and ranges. Different individual location preferences can lead to the development of hen subpopulations that are characterised by various health, welfare and performance parameters. Understanding the complexity of hen movement and hen interactions within their environment provides an opportunity to limit the disadvantages that are associated with housing in loose husbandry systems and aids in decision-making. Monitoring hen movement using modern technologies such as radio-frequency identification (RFID), optical flow patterns, image analysis and three-dimensional (3D) cameras allows the accumulation of big data for data mining, clustering and machine learning. Integrating individual-based management systems into modern flock management will not only help improve the care of under-performing hens, but also ensure that elite hens are able to use their full genetic potential, allowing an ethical, sustainable and welfare friendly egg production. This review highlights the dynamics and impact of hen movement in free-range systems, reviews existing knowledge relevant for feeding hens in non-cage systems, and outlines recent technological advances and strategies to improve the management of free-range laying hens.

Additional keywords: egg, health, husbandry, nutrition, poultry, welfare.


References

Aerni V, Rinkhof MWG, Wechsler B, Oester H, Fröhlich E (2005) Productivity and mortality of laying hens in aviaries: a systematic review. World’s Poultry Science Journal 61, 130–142.
Productivity and mortality of laying hens in aviaries: a systematic review.Crossref | GoogleScholarGoogle Scholar |

Aguado E, Pascaretti-Grizon F, Goyenvalle E, Audran M, Chappard D (2015) Bone mass and bone quality are altered by hypoactivity in the chicken. PLoS One 10, e0116763
Bone mass and bone quality are altered by hypoactivity in the chicken.Crossref | GoogleScholarGoogle Scholar | 25635404PubMed |

Allen J, Perry GC (1975) Feather pecking and cannibalism in a caged layer flock. British Poultry Science 16, 441–451.
Feather pecking and cannibalism in a caged layer flock.Crossref | GoogleScholarGoogle Scholar | 1156927PubMed |

Appleby MC, Smith SF, Hughes BO (1993) Nesting, dust bathing and perching by laying hens in cages: effects of design on behaviour and welfare. British Poultry Science 34, 835–847.
Nesting, dust bathing and perching by laying hens in cages: effects of design on behaviour and welfare.Crossref | GoogleScholarGoogle Scholar | 8156422PubMed |

Arzey GG, Kirkland PD, Arzey KE, Frost M, Maywood P, Conaty HAC, Iannello P, Dwyer DE, Ratnamohan M, Mcohie K, Selleck P (2012) Influenza virus A (H10N7) in chickens and poultry abattoir workers, Australia. Emerging Infectious Diseases 18, 814–816.
Influenza virus A (H10N7) in chickens and poultry abattoir workers, Australia.Crossref | GoogleScholarGoogle Scholar | 22516302PubMed |

Barnett JL, Cronin GM, Tauson R, Downing JA, Vijaya J, Lowenthal JW, Butler KL (2005) The effects of a perch, dust bath and nest box in furnished cages on the welfare of laying hens. Animal Science Papers and Reports 23, 111–119.

Barrett JA, Rayner C, Gill R, Willings TH, Bright A (2014) Smothering in UK free-range flocks. Part 1: incidence, location, timing and management. The Veterinary Record 175, 19–24.
Smothering in UK free-range flocks. Part 1: incidence, location, timing and management.Crossref | GoogleScholarGoogle Scholar |

Bright A, Johnson EA (2011) Smothering in commercial free-range laying hens: a preliminary investigation. The Veterinary Record 168, 512
Smothering in commercial free-range laying hens: a preliminary investigation.Crossref | GoogleScholarGoogle Scholar | 21558127PubMed |

Campbell DLM, Makagon MM, Swanson JC, Siegford JM (2016) Perch use by laying hens in a commercial aviary. Poultry Science 95, 1736–1742.
Perch use by laying hens in a commercial aviary.Crossref | GoogleScholarGoogle Scholar |

Campbell DLM, Hinch GN, Dyall TR, Warin L, Little BA, Lee C (2017) Outdoor stocking density in free-range laying hens: radio-frequency identification of impacts on range use. Animal 11, 121–130.
Outdoor stocking density in free-range laying hens: radio-frequency identification of impacts on range use.Crossref | GoogleScholarGoogle Scholar |

Campo JL, Gil MG, Dávila SG (2007) Differences among white-, tinted-and brown-egg laying hens for incidence of eggs laid on the floor and for oviposition time. Archiv für Geflügelkunde 71, 105–109.

Centers for Disease Control and Prevention (CDC) (2019) ‘Avian influenza A virus infection of humans.’ Available at https://www.cdc.gov/flu/avianflu/north-american-lineage.htm [Verified 20 April 2019]

Chousalkar KK, Roberts JR (2012) Recovery of Salmonella from eggshell wash, eggshell crush, and egg internal contents of unwashed commercial shell eggs in Australia. Poultry Science 91, 1739–1741.
Recovery of Salmonella from eggshell wash, eggshell crush, and egg internal contents of unwashed commercial shell eggs in Australia.Crossref | GoogleScholarGoogle Scholar | 22700522PubMed |

Chousalkar KK, Flynn P, Sutherland M, Roberts JR, Cheetham BF (2010) Recovery of Salmonella and Escherichia coli from commercial egg shells and effect of translucency on bacterial penetration in eggs. International Journal of Food Microbiology 142, 207–213.
Recovery of Salmonella and Escherichia coli from commercial egg shells and effect of translucency on bacterial penetration in eggs.Crossref | GoogleScholarGoogle Scholar | 20663580PubMed |

Cloutier S, Newberry RC, Forster CT, Girsberger KM (2000) Does pecking at inanimate stimuli predict cannibalistic behaviour in domestic fowl? Applied Animal Behaviour Science 66, 119–133.
Does pecking at inanimate stimuli predict cannibalistic behaviour in domestic fowl?Crossref | GoogleScholarGoogle Scholar |

Conraths FJ, Globig A, Sauter-Louis C, Dietze K, Homeier T, Probst C, Gethmann J, Depner K, Wysocki P, Reimer N, Staubach C, Grund C, Harder T, Starick E, Pohlmann A, Höper D, Beer M, Mettenleiter TC (2016) Making worst case scenarios real: The the introduction of highly pathogenic avian influenza of subtype H5N8 led to the largest fowl plague outbreak ever record in Germany. Lohmann Information 51,

Daghir NJ (1973) Energy requirements of laying hens in a semi-arid continental climate. British Poultry Science 14, 451–461.
Energy requirements of laying hens in a semi-arid continental climate.Crossref | GoogleScholarGoogle Scholar |

De Reu K, Grijspeerdt K, Heyndrickx M, Zoons J, De Baere K, Uyttendaele M, Debevere J, Herman L (2005) Bacterial eggshell contamination in conventional cages, furnished cages and aviary housing systems for laying hens. British Poultry Science 46, 149–155.
Bacterial eggshell contamination in conventional cages, furnished cages and aviary housing systems for laying hens.Crossref | GoogleScholarGoogle Scholar | 15957434PubMed |

De Reu K, Grijspeerdt K, Heyndrickx M, Uyttendaele M, Debevere J, Herman L (2006) Bacterial shell contamination in the egg collection chains of different housing systems for laying hens. British Poultry Science 47, 163–172.
Bacterial shell contamination in the egg collection chains of different housing systems for laying hens.Crossref | GoogleScholarGoogle Scholar | 16641027PubMed |

Dennis RL, Fahey AG, Cheng HW (2008) Different effects of individual identification systems on chicken well-being. Poultry Science 87, 1052–1057.
Different effects of individual identification systems on chicken well-being.Crossref | GoogleScholarGoogle Scholar | 18492991PubMed |

Directive EU 1999 Council Directive 99/74/EC of 19 July 1999 laying down minimum standards for the protection of laying hens.Official Journal of the European Communities5357

Drost H, van den Drift DW (1992) Working conditions in an aviary system for laying hens. In ‘Proceedings of world’s poultry congress’, Amsterdam, The Netherlands, 20–24 September 1992. pp. 734–738.

Durali T, Groves P, Cowieson A, Singh M (2014) Evaluating range usage of commercial free range broilers and its effect on birds performance using radio frequency identification (RFID) technology. In ‘Australian poultry science symposium’, Sydney, NSW, Australia. pp. 103–106.

Einhorn HJ, Hogarth RM (1981) Behavioral decision theory: processes of judgement and choice. Annual Review of Psychology 32, 53–88.
Behavioral decision theory: processes of judgement and choice.Crossref | GoogleScholarGoogle Scholar |

Eits RM, Kwakkel RP, Reindsen BGE, Zandstra T, Maatsman AA (2005) Effect of housing system on balanced protein requirements in laying hens. In ‘Proceedings of the 15th European symposium poultry nutrition’, 25–29 September, Hungary. pp. 133–135.

Ellen HH, Bottcher RW, von Wachenfelt E, Takai E (2000) Dust levels and control methods in poultry houses. Journal of Agricultural Safety and Health 6, 275–282.
Dust levels and control methods in poultry houses.Crossref | GoogleScholarGoogle Scholar | 11217692PubMed |

Elson HA, Croxall R (2006) European study on the comparative welfare of laying hens in cage and non-cage systems. Archiv für Geflügelkunde 70, 194–198.

Feiyang Z, Yueming H, Liancheng C, Lihong G, Wenjie D, Lu W (2016) Monitoring behavior of poultry based on RFID radio frequency network. International Journal of Agricultural and Biological Engineering 9, 139–147.

Ferrante V, Lolli S, Vezzoli G, Cavalchini LG (2009) Effects of two different rearing systems (organic and barn) on production performance, animal welfare traits and egg quality characteristics in laying hens. Italian Journal of Animal Science 8, 165–174.
Effects of two different rearing systems (organic and barn) on production performance, animal welfare traits and egg quality characteristics in laying hens.Crossref | GoogleScholarGoogle Scholar |

Fossum O, Jansson DS, Etterlin PE, Vågsholm I (2009) Causes of mortality in laying hens in different housing systems in 2001 to 2004. Acta Veterinaria Scandinavica 51, 3
Causes of mortality in laying hens in different housing systems in 2001 to 2004.Crossref | GoogleScholarGoogle Scholar | 19146656PubMed |

Gebhardt-Henrich SG, Fröhlich EKF, Burose F, Fleurent J, Gantner M, Zähner M (2014a) Individual tracking of laying hens with an RFID-System. Landtechnik 69, 301–307.

Gebhardt-Henrich SG, Toscano MJ, Fröhlich EK (2014b) Use of outdoor ranges by laying hens in different sized flocks. Applied Animal Behaviour Science 155, 74–81.
Use of outdoor ranges by laying hens in different sized flocks.Crossref | GoogleScholarGoogle Scholar |

GfE (1999) ‘Empfehlungen zur Energie- und Nährstoffversorgung der Legehennen und Masthühner (Broiler).’ (DLG-Verlag: Frankfurt/Main, Germany)

Glatz PC, Ru YJ (2002) Free-range poultry in a pasture/crop rotation system. In ‘Proceedings 2002 poultry information exchange’, 14–16 April 2002. pp. 7–10. (Caboolture, Qld)

Glatz P, Runge G (2017) ‘Managing fowl behaviour: a best practice guide to help manage feather pecking and cannibalism in pullet, layer and breeder flocks.’ (Australian Eggs: Sydney)

Halvorson DA, Kelleher CJ, Senne DA (1985) Epizootiology of avian influenza: effect of season on incidence in sentinel ducks and domestic turkeys in Minnesota. Applied Environmental Microbiology 49, 914–919.

Heikkilä M, Wichman A, Gunnarsson S, Valros A (2006) Development of perching behaviour in chicks reared in enriched environment. Applied Animal Behaviour Science 99, 145–156.
Development of perching behaviour in chicks reared in enriched environment.Crossref | GoogleScholarGoogle Scholar |

Icken W, Cavero D, Schmutz M, Thurner S, Wendl G, Preisinger R (2008) Analysis of the free range behaviour of laying hens and the genetic and phenotypic relationships with laying performance. British Poultry Science 49, 533–541.
Analysis of the free range behaviour of laying hens and the genetic and phenotypic relationships with laying performance.Crossref | GoogleScholarGoogle Scholar | 18836899PubMed |

Icken W, Thurner S, Heinrich A, Kaiser A, Cavero D, Wendl G, Fries R, Schmutz M, Preisinger R (2013) Higher precision level at individual laying performance tests in non-cage housing systems. Poultry Science 92, 2276–2282.
Higher precision level at individual laying performance tests in non-cage housing systems.Crossref | GoogleScholarGoogle Scholar | 23960109PubMed |

Iqbal Z, Roberts J, Perez-Maldonado RA, Goodarzi Boroojeni F, Swick RA, Ruhnke I (2018) Pasture, multi-enzymes, benzoic acid and essential oils positively influence performance, intestinal organ weight and egg quality in free-range laying hens. British Poultry Science 59, 180–189.
Pasture, multi-enzymes, benzoic acid and essential oils positively influence performance, intestinal organ weight and egg quality in free-range laying hens.Crossref | GoogleScholarGoogle Scholar | 29130331PubMed |

Kahn LP, Johnson IR, Rowe JB, Hogan L, Boshoff J (2017) ASKBILL as a web-based program to enhance sheep well-being and productivity. Animal Production Science 57, 2257–2262.
ASKBILL as a web-based program to enhance sheep well-being and productivity.Crossref | GoogleScholarGoogle Scholar |

Kang HK, Park SB, Kim SH, Kim CH (2016) Effects of stock density on the laying performance, blood parameter, corticosterone, litter quality, gas emission and bone mineral density of laying hens in floor pens. Poultry Science 95, 2764–2770.
Effects of stock density on the laying performance, blood parameter, corticosterone, litter quality, gas emission and bone mineral density of laying hens in floor pens.Crossref | GoogleScholarGoogle Scholar | 27578881PubMed |

Käppeli S, Gebhardt-Henrich SG, Fröhlich E, Pfulg A, Stoffel MH (2011) Prevalence of keel bone deformities in Swiss laying hens British Poultry Science 52, 531–536.
Prevalence of keel bone deformities in Swiss laying hensCrossref | GoogleScholarGoogle Scholar | 22029778PubMed |

Knierim U (2006) Animal welfare aspects of outdoor runs for laying hens: a review. NJAS Wageningen Journal of Life Sciences 54, 133–145.
Animal welfare aspects of outdoor runs for laying hens: a review.Crossref | GoogleScholarGoogle Scholar |

Kolakshyapati M, Flavel R, Sibanda TZ, Ruhnke I (2019a) Range access has no beneficial effect on tibia health of free-range laying hens while body weight is positively correlated with different bone parameters. British Poultry Science, in press.

Kolakshyapati M, Wu SB, Sibanda TZ, Ruhnke I (2019b) Body weight but not range usage is the main factor affecting net energy utilisation in commercial free-range laying hens. Animal Nutrition, in press

Lambton SL, Knowles TG, Yorke C, Nicol CJ (2015) The risk factors affecting the development of vent pecking and cannibalism in free-range and organic laying hens. Animal Welfare 24, 101–111.
The risk factors affecting the development of vent pecking and cannibalism in free-range and organic laying hens.Crossref | GoogleScholarGoogle Scholar |

Larsen H, Cronin G, Gebhardt-Henrich S, Smith C, Hemsworth P, Rault JL (2017) Individual ranging behaviour patterns in commercial free-range layers as observed through RFID tracking. Animals 7, 1–16.
Individual ranging behaviour patterns in commercial free-range layers as observed through RFID tracking.Crossref | GoogleScholarGoogle Scholar |

Larsson BM, Larsson K, Malmberg P, Mårtensson L, Palmberg L (1999) Airway responses in naïve subjects to exposure in poultry houses: comparison between cage rearing systems and alternative rearing system for laying hens. American Journal of Industrial Medicine 35, 142–149.
Airway responses in naïve subjects to exposure in poultry houses: comparison between cage rearing systems and alternative rearing system for laying hens.Crossref | GoogleScholarGoogle Scholar | 9894538PubMed |

Leenstra F, Maurer V, Bestman M, Van Sambeek F, Zeltner E, Reuvekamp B, Galea F, Van Niekerk T (2012) Performance of commercial laying hen genotypes on free range and organic farms in Switzerland, France and the Netherlands. British Poultry Science 53, 282–290.
Performance of commercial laying hen genotypes on free range and organic farms in Switzerland, France and the Netherlands.Crossref | GoogleScholarGoogle Scholar | 22978584PubMed |

Leenstra F, Maurer V, Galea F, Bestman M, Amsler-Kepalaite Z, Visscher J, Vermeij I, Van Krimpen M (2014) Laying hen performance in different production systems; why do they differ and how to close the gap? Results of discussions with groups of farmers in The Netherlands, Switzerland and France, benchmarking and model calculations. Archiv für Geflügelkunde 78, 1–10.

Leeson S, Morrison WD (1978) Effect of feather cover on feed efficiency in laying birds. Poultry Science 57, 1094–1096.
Effect of feather cover on feed efficiency in laying birds.Crossref | GoogleScholarGoogle Scholar |

Leterrier C, Vallee C, Constantin P, Chagneau AM, Lessire M, Lescoat P, Berri C, Baeza E, Bizeray D, Bouvarel I (2008) Sequential feeding with variations in energy and protein levels improves gait score in meat-type chickens Animals (Basel) 2, 1658–1665.

Leyendecker M, Hamann H, Hartung J, Kamphues J, Neumann U, Suerie C, Distl O (2005) Keeping laying hens in furnished cages and an aviary housing system enhances their bone stability. British Poultry Science 46, 536–544.
Keeping laying hens in furnished cages and an aviary housing system enhances their bone stability.Crossref | GoogleScholarGoogle Scholar | 16359105PubMed |

Marx G, Klein S, Weigend S (2002) An automated nest box system for individual performance testing and parentage control in laying hens maintained in groups. Archiv für Geflügelkunde 66, 141–144.

McCarthy C (2019) Evaluation of image analysis for detecting chicken behaviours for welfare monitoring. In ‘Proceedings of the Australasian Veterinarian Poultry Association’, 2–21 February 2019, Sydney, NSW, Australia.

Mench JA (2002) Broiler breeders: feed restriction and welfare. World’s Poultry Science Journal 58, 23–29.
Broiler breeders: feed restriction and welfare.Crossref | GoogleScholarGoogle Scholar |

Moinard C, Statham P, Haskell MJ, McCorquodale C, Jones RB, Green PR (2004) Accuracy of laying hens in jumping upwards and downwards between perches in different light environments. Applied Animal Behaviour Science 85, 77–92.
Accuracy of laying hens in jumping upwards and downwards between perches in different light environments.Crossref | GoogleScholarGoogle Scholar |

Mourits MCM, Dijkhuizen AA, Huirne RBM, Galligan DT (1997) Technical and economic models to support heifer management decisions: basic concepts. Journal of Dairy Science 80, 1406–1415.
Technical and economic models to support heifer management decisions: basic concepts.Crossref | GoogleScholarGoogle Scholar |

Nääs IDA, Laganá M, Mollo Neto M, Canuto S, Pereira DF (2012) Image analysis for assessing broiler breeder behavior response to thermal environment. Engenharia Agrícola 32, 624–632.
Image analysis for assessing broiler breeder behavior response to thermal environment.Crossref | GoogleScholarGoogle Scholar |

Nakarmi AD, Tang L, Xin H (2014) Automated tracking and behavior quantification of laying hens using 3D computer vision and radio frequency identification technologies. Transactions of the ASABE 57, 1455–1472.

Nasr MAF, Nicol CJ, Murrell JC (2012a) Do laying hens with keel bone fractures experience pain? PLoS One 7, e42420
Do laying hens with keel bone fractures experience pain?Crossref | GoogleScholarGoogle Scholar |

Nasr MAF, Murrell J, Wilkins LJ, Nicol CJ (2012b) The effect of keel fractures on egg-production parameters, mobility and behaviour in individual laying hens. Animal Welfare 21, 127–135.
The effect of keel fractures on egg-production parameters, mobility and behaviour in individual laying hens.Crossref | GoogleScholarGoogle Scholar |

Neves DP, Mehdizadeh SA, Tscharke M, deAlencar Nääs I, Banhazi TM (2015) Detection of flock movement and behaviour of broiler chickens at different feeders using image analysis. Information Processing in Agriculture 2, 177–182.
Detection of flock movement and behaviour of broiler chickens at different feeders using image analysis.Crossref | GoogleScholarGoogle Scholar |

Nicol CJ, Pötzsch C, Lewis K, Green LE (2003) Matched concurrent case-control study of risk factors for feather pecking in hens on free-range commercial farms in the UK. British Poultry Science 44, 515–523.
Matched concurrent case-control study of risk factors for feather pecking in hens on free-range commercial farms in the UK.Crossref | GoogleScholarGoogle Scholar | 14584840PubMed |

Nicol CJ, Brown SN, Glen E, Pope SJ, Short FJ, Warriss PD, Zimmerman PH, Wilkins LJ (2006) Effects of stocking density, flock size and management on the welfare of laying hens in single-tier aviaries. British Poultry Science 47, 135–146.
Effects of stocking density, flock size and management on the welfare of laying hens in single-tier aviaries.Crossref | GoogleScholarGoogle Scholar | 16641024PubMed |

Peguri A, Coon C (1993) Effect of feather coverage and temperature on layer performance. Poultry Science 72, 1318–1329.
Effect of feather coverage and temperature on layer performance.Crossref | GoogleScholarGoogle Scholar |

Perez-Munoz F, Hoff SJ, Van Hal T (1998) A quasi ad-libitum electronic feeding system for gestating sows in loose housing. Computers and Electronics in Agriculture 19, 277–288.
A quasi ad-libitum electronic feeding system for gestating sows in loose housing.Crossref | GoogleScholarGoogle Scholar |

Protais J, Queguiner S, Boscher E, Piquet JC, Nagard B, Salvat G (2003) Effect of housing systems on the bacterial flora of egg shells. British Poultry Science 44, 788–790.
Effect of housing systems on the bacterial flora of egg shells.Crossref | GoogleScholarGoogle Scholar | 14965113PubMed |

Rockart JF (1979) Chief executives define their own data needs. Harvard Business Review 57, 81–93.

Rodenburg TB, Van Hierden YM, Buitenhuis AJ, Riedstra B, Koene P, Korte 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, Tuyttens FAM, De Reu K, Herman L, Zoons J, Sonck B (2008) Welfare assessment of laying hens in furnished cages and non-cage systems: an on-farm comparison. Animal Welfare 17, 363–373.

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 69, 361–374.

Rodriguez-Aurrekoetxea A, Estevez I (2016) Use of space and its impact on the welfare of laying hens in a commercial free-range system. Poultry Science 95, 2503–2513.
Use of space and its impact on the welfare of laying hens in a commercial free-range system.Crossref | GoogleScholarGoogle Scholar | 27433014PubMed |

Roll VFB, Levrino GAM, Briz RC (2008) Rearing system and behavioural adaptation of laying hens to furnished cages. Ciência Rural 38, 1997–2003.
Rearing system and behavioural adaptation of laying hens to furnished cages.Crossref | GoogleScholarGoogle Scholar |

Rossing W (1976) Cow identification for individual feeding in or outside the milking parlor. In ‘Proceedings of the symposium on animal identification systems and their applications’, 8–9 April 1976, Wageningen, The Netherlands. pp. 1167–1180.

Ruhnke I, Sibanda TZ (2018) Nutritional management of free range laying hens. In ‘Proceedings of the poultry information exchange’, 3–5 June 2018, Gold Coast, Qld, Australia. pp. 147–148.

Ruhnke I, Cowling G, Sommerlad M, Swick R, Choct M (2015) Gut impaction in free rage hens. In ‘Proceedings of the annual Australian poultry science symposium’, 9–11 February 2015, Sydney, NSW, Australia. pp. 242–244.

Sales GT, Green AR, Gates RS, Brown-Brandl TM, Eigenberg RA (2015) Quantifying detection performance of a passive low-frequency RFID system in an environmental preference chamber for laying hens. Computers and Electronics in Agriculture 114, 261–268.
Quantifying detection performance of a passive low-frequency RFID system in an environmental preference chamber for laying hens.Crossref | GoogleScholarGoogle Scholar |

Samiullah S, Roberts JR, Chousalkar KK (2014) Effect of production system and flock age on egg quality and total bacterial load in commercial laying hens. Journal of Applied Poultry Research 23, 59–70.
Effect of production system and flock age on egg quality and total bacterial load in commercial laying hens.Crossref | GoogleScholarGoogle Scholar |

Sibanda TZ, Walkden-Brown SW, Kolakshyapati M, Dawson B, Schneider D, Welch M, Iqbal Z, Cohen-Barnhouse A, Morgan NK, Boshoff J, Ruhnke I (2019) Flock use of the range is associated with the use of different components of a multi-tier aviary system in commercial free-range laying hens. British Poultry Science.

Singh M, Cowieson AJ (2013) Range use and pasture consumption in free-range poultry production. Animal Production Science 53, 1202–1208.
Range use and pasture consumption in free-range poultry production.Crossref | GoogleScholarGoogle Scholar |

Singh M, Hernandez CE, Hinch G, Cowieson AJ (2016) Wanderers versus stay at home: who has the better guts? In ‘Proceedings of the Australian poultry science symposium’, 14–17 February 2016, Sydney, NSW, Australia. pp. 78–81. (Poultry Science Foundation: Sydney)

Sirovnik J, Würbel H, Toscano MJ (2018) Feeder space affects access to the feeder, aggression, and feed conversion in laying hens in an aviary system. Applied Animal Behaviour Science 198, 75–82.
Feeder space affects access to the feeder, aggression, and feed conversion in laying hens in an aviary system.Crossref | GoogleScholarGoogle Scholar |

Sossidou EN, Dal Bosco A, Elson HA, Fontes CMGA (2011) Pasture-based systems for poultry production: implications and perspectives. World’s Poultry Science Journal 67, 47–58.
Pasture-based systems for poultry production: implications and perspectives.Crossref | GoogleScholarGoogle Scholar |

Stokholm NM, Permin A, Bisgaard M, Christensen JP (2010) Causes of mortality in commercial organic layers in Denmark. Avian Diseases Digest 5, e56–e57.
Causes of mortality in commercial organic layers in Denmark.Crossref | GoogleScholarGoogle Scholar |

Svihus B (2011) The gizzard: function, influence of diet structure and effects on nutrient availability. World’s Poultry Science Journal 67, 207–224.
The gizzard: function, influence of diet structure and effects on nutrient availability.Crossref | GoogleScholarGoogle Scholar |

Thurner S, Wendl G, Preisinger R (2006) Funnel nest box: a system for automatic recording of individual performance and behaviour of laying hens in floor management. In ‘Proceedings of the XII European poultry conference’, 10–14 September 2006, Verona, Italy. p. 52.

Tiller H (2001) Nutrition and animal welfare in egg production systems. In ‘13th European symposium Poultry Nutrition, 30 September – 4 October 2001, Blankenberge, Belgium. pp. 226–232.

Trevarthen A, Michael K (2007) Beyond mere compliance of RFID regulations by the farming community: a case study of the Cochrane dairy farm. In ‘International conference on the management of mobile business’, 9–11 July 2007, Toronto, Canada. pp. 8–8. (ICMB 2007).

Van Horne PLM (1996) Production and economic results of commercial flocks with white layers in aviary systems and battery cages. British Poultry Science 37, 255–261.
Production and economic results of commercial flocks with white layers in aviary systems and battery cages.Crossref | GoogleScholarGoogle Scholar |

Voulodimos AS, Patrikakis CZ, Sideridis AB, Ntafis VA, Xylouri EM (2010) A complete farm management system based on animal identification using RFID technology. Computers and Electronics in Agriculture 70, 380–388.
A complete farm management system based on animal identification using RFID technology.Crossref | GoogleScholarGoogle Scholar |

Whay HR, Main DCJ, Green LE, Heaven G, Howell H, Morgan M, Pearson A, Webster AJF (2007) Assessment of the behavior and welfare of laying hens on free-range units. The Veterinary Record 161, 119–128.
Assessment of the behavior and welfare of laying hens on free-range units.Crossref | GoogleScholarGoogle Scholar | 17660465PubMed |

Wichman A, Heikkilä M, Valros A, Forkman B, Keeling LJ (2007) Perching behaviour in chickens and its relation to spatial ability. Applied Animal Behaviour Science 105, 165–179.
Perching behaviour in chickens and its relation to spatial ability.Crossref | GoogleScholarGoogle Scholar |

Wilkins LJ, Brown SN, Zimmerman PH, Leeb C, Nicol CJ (2004) Investigation of palpation as a method for determining the prevalence of keel and furculum damage in laying hens. The Veterinary Record 155, 547–549.
Investigation of palpation as a method for determining the prevalence of keel and furculum damage in laying hens.Crossref | GoogleScholarGoogle Scholar | 15559420PubMed |

Wisanmongkol J, Pongpaibool P (2009) A passive UHF RFID tag for poultry traceability. In ‘The 2009 international symposium on antennas and propagation’, 20–23 October 2009, Bangkok, Thailand.

Zaninelli M, Costa A, Tangorra F, Rossi L, Agazzi A, Savoini G (2015) Preliminary evaluation of a nest usage sensor to detect double nest occupations of laying hens. Sensors 15, 2680–2693.
Preliminary evaluation of a nest usage sensor to detect double nest occupations of laying hens.Crossref | GoogleScholarGoogle Scholar | 25629704PubMed |

Zaninelli M, Rossi L, Costa A, Tangorra FM, Guarino M, Savoini G (2016) Performance of injected RFID transponders to collect data about laying performance and behaviour of hens. Large Animal Review 22, 77–82.

Zaninelli M, Redaelli V, Luzi F, Bontempo V, Dell’Orto V, Savoini G (2017) A monitoring system for laying hens that uses a detection sensor based on infrared technology and image pattern recognition. Sensors 17, 1195, 1-17
A monitoring system for laying hens that uses a detection sensor based on infrared technology and image pattern recognition.Crossref | GoogleScholarGoogle Scholar | 28538654PubMed |

Zimmerman PH, Lindberg AC, Pope SJ, Glen E, Bolhuis JE, Nicol CJ (2006) The effect of stocking density, flock size and modified management on laying hen behaviour and welfare in a non-cage system. Applied Animal Behaviour Science 101, 111–124.
The effect of stocking density, flock size and modified management on laying hen behaviour and welfare in a non-cage system.Crossref | GoogleScholarGoogle Scholar |

Zuidhof MJ, Fedorak MV, Ouellette CA, Wenger II (2017) Precision feeding: innovative management of broiler breeder feed intake and flock uniformity. Poultry Science 96, 2254–2263.
Precision feeding: innovative management of broiler breeder feed intake and flock uniformity.Crossref | GoogleScholarGoogle Scholar | 28159999PubMed |