{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,18]],"date-time":"2026-09-18T20:47:31Z","timestamp":1789764451783,"version":"4.0.1"},"reference-count":121,"publisher":"PeerJ","license":[{"start":{"date-parts":[[2023,4,4]],"date-time":"2023-04-04T00:00:00Z","timestamp":1680566400000},"content-version":"unspecified","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Open Access Publication Fund of the University of Bonn"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"abstract":"<jats:sec>\n               <jats:title>Background<\/jats:title>\n               <jats:p>One priority for animal welfare is for animals to experience less fear, especially during human contact. For domestic animals, breeds that are less fearful may provide genetic resources to develop strains with improved welfare due to lower susceptibility to fear. Genetic predispositions inherited in these breeds might reflect the large diversity of chicken breeds. The goal of the present study was to systematically test a diverse group of chicken breeds to search for breeds that experience less fear.<\/jats:p>\n            <\/jats:sec>\n            <jats:sec>\n               <jats:title>Methods<\/jats:title>\n               <jats:p>Nineteen chicken breeds from commercial hybrid lines, native layer-type, meat-type and dual-purpose breeds, ornamental breeds as well as bantam breeds were tested in a standardized tonic immobility (TI) test. Chickens were manually restrained on their back, and the time to first head movement and first leg movement, the duration of TI, as well as the number of attempts needed to induce TI were measured.<\/jats:p>\n            <\/jats:sec>\n            <jats:sec>\n               <jats:title>Results<\/jats:title>\n               <jats:p>The TI response differed among chicken breeds (<jats:italic>p<\/jats:italic>\u00a0\u2264\u00a00.001) for na\u00efve, mature hens. The median number of attempts required to induce TI ranged from 1 to 2 and did not differ significantly among breeds. Median durations were much more variable, with Lohmann Brown showing shortest durations (6 s, 12 s, 58 s for time to first head movement, first leg movement and total duration of TI, respectively). In contrast, medians reached the maximum of 600 s for all three measures in German Creepers. Repeated tests on the same individuals did not affect attempts needed to induce TI nor TI durations. Breeds clustered into two main groups, with layer-type native breeds and ornamental breeds having longer TI durations, and bantam, dual-purpose and meat-type native breeds having shorter TI durations.<\/jats:p>\n            <\/jats:sec>\n            <jats:sec>\n               <jats:title>Conclusions<\/jats:title>\n               <jats:p>Our findings provide evidence for substantial variation of fearfulness among breeds. This variation could be linked to the intended use during the breed\u2019s specific history. Knowledge and quantitative measurement of these behavioural responses provide the opportunity to improve welfare through selection and future breeding.<\/jats:p>\n            <\/jats:sec>","DOI":"10.7717\/peerj.14703","type":"journal-article","created":{"date-parts":[[2023,4,4]],"date-time":"2023-04-04T07:20:46Z","timestamp":1680592846000},"page":"e14703","source":"Crossref","is-referenced-by-count":12,"title":["Differences among domestic chicken breeds in tonic immobility responses as a measure of fearfulness"],"prefix":"10.7717","volume":"11","author":[{"given":"Inga","family":"Tiemann","sequence":"first","affiliation":[{"name":"Institute of Agricultural Engineering, University of Bonn, Bonn, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Senta","family":"Becker","sequence":"additional","affiliation":[{"name":"Institute of Agricultural Engineering, University of Bonn, Bonn, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jocelyn","family":"Fournier","sequence":"additional","affiliation":[{"name":"Department of Animal & Poultry Science, University of Saskatchewan, Saskatoon, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Daalkhaijav","family":"Damiran","sequence":"additional","affiliation":[{"name":"Department of Animal & Poultry Science, University of Saskatchewan, Saskatoon, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Wolfgang","family":"B\u00fcscher","sequence":"additional","affiliation":[{"name":"Institute of Agricultural Engineering, University of Bonn, Bonn, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sonja","family":"Hillemacher","sequence":"additional","affiliation":[{"name":"Institute of Agricultural Engineering, University of Bonn, Bonn, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"4443","published-online":{"date-parts":[[2023,4,4]]},"reference":[{"key":"10.7717\/peerj.14703\/ref-1","doi-asserted-by":"publisher","first-page":"95","DOI":"10.1016\/j.beproc.2013.07.004","article-title":"Differences in responses to repeated fear-relevant stimuli between Nagoya and White Leghorn chicks","volume":"99","author":"Abe","year":"2013","journal-title":"Behavioural Processes"},{"issue":"7","key":"10.7717\/peerj.14703\/ref-2","doi-asserted-by":"publisher","first-page":"3343","DOI":"10.1016\/j.psj.2020.04.008","article-title":"Effects of a partially perforated flooring system on animal based welfare indicators in broiler housing","volume":"99","author":"Adler","year":"2020","journal-title":"Poultry Science"},{"key":"10.7717\/peerj.14703\/ref-3","doi-asserted-by":"publisher","first-page":"e35162","DOI":"10.1371\/journal.pone.0035162","article-title":"Heritability and genetic correlations of fear-related behaviour in red junglefowl\u2013possible implications for early domestication","volume":"7","author":"Agnvall","year":"2012","journal-title":"PLOS ONE"},{"key":"10.7717\/peerj.14703\/ref-4","doi-asserted-by":"publisher","first-page":"20150509","DOI":"10.1098\/rsbl.2015.0509","article-title":"Is domestication driven by reduced fear of humans? 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