| 1. |
- Hedlund, Louise, 1987-, et al.
(författare)
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Effects of stress during commercial hatching on growth, egg production and feather pecking in laying hens
- 2022
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Ingår i: PLOS ONE. - San Francisco, CA, United States : Public Library of Science. - 1932-6203. ; 17:1
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Tidskriftsartikel (refereegranskat)abstract
- Every year, billions of egg layer chicks around the world are hatched under highly stressful, industrial circumstances. Here, it is investigated how the stressful procedure in the commercial hatchery, including incubation, hatching, processing, and transport affects the chicks with regards to traits relevant for the egg production industry. These traits were compared to those of a control group hatched in a small incubator and handled gently och quietly in a quiet room without any processing and transport. The chicks were weighed at hatch and at eight additional time points: 4 days, 1 week (w), 2 w, 3 w, 5 w, 8 w, 20 w and 25 w of age. Feather pecking was studied at 15 w of age and damages to the feathers and injuries on the comb and wattle were assessed at 25 w of age. From 19 w of age, eggs were collected on three days per week, counted and weighed. Chicks from a commercial hatchery had a lower hatch weight than control chicks (p<0.001). At 20 w of age, the weight of the commercial hatched chicks was still numerically lower, although this did not reach statistical significance. Commercially hatched chicks tended to show more feather pecking behaviour at 15 w of age compared to control chicks (p<0.1), although feather condition at 25 w of age showed the opposite pattern. Regarding production, commercially hatched chickens laid fewer (p<0.05) and smaller (p<0.05) eggs than chicks hatched and handled under calm circumstances. From this experiment, it is concluded that the stressful experience in the commercial hatchery has an overall negative effect on traits relevant for the industry.
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| 2. |
- Hedlund, Louise, et al.
(författare)
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Incubation and hatching conditions of laying hen chicks explain a large part of the stress effects from commercial large-scale hatcheries
- 2021
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Ingår i: Poultry Science. - : ELSEVIER. - 0032-5791 .- 1525-3171. ; 100:1
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Tidskriftsartikel (refereegranskat)abstract
- In commercial egg production, laying hen chicks are exposed to several stressful events during incubation, hatching, and their first hours in life. We have previously shown that hatching and processing are associated with increased corticosterone concentration and further affect behavior and stress sensitivity in a short- as well as long-term perspective. However, it is not known whether these long-term stress effects are caused by the hatchery processing (sex sorting, vaccination, conveying, and loading for transport) or if they are mainly caused by potentially stressful events before processing, during incubation and hatching. In the present study, the aim was to assess the effects of incubation and hatching only, compared to stress effects from the entire hatchery processing. We compared Lohmann LSL chicks incubated, hatched, and processed in a commercial hatchery with chicks incubated and hatched at the same time but not further processed. We studied behavior in a novel arena and during tonic immobility, as well as weight development and corticosterone reaction during a stress challenge. Processed chicks had poorer weight development and were more active in the novel arena test. However, there were no significant differences between the groups in corticosterone reactivity or tonic immobility. When comparing with previous data, both groups had elevated corticosterone concentrations compared to what we had previously reported from chicks hatched under calm and nonstressful conditions. In conclusion, incubation and hatching alone caused long-term stress effects in chickens, but further processing exacerbated these effects to some extent.
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| 3. |
- Hedlund, Louise, et al.
(författare)
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Stress during Commercial Hatchery Processing Induces Long-Time Negative Cognitive Judgement Bias in Chickens
- 2021
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Ingår i: Animals. - : MDPI. - 2076-2615. ; 11:4
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Tidskriftsartikel (refereegranskat)abstract
- Simple Summary Worldwide, billions of laying hen chicks are incubated, hatched and processed in industrial hatcheries every year. When exposed to stress, hormones are incorporated in the feathers of the birds. Here, we measured levels of the stress hormone corticosterone to investigate possible stress during the incubation. Further, animals can perceive their environment either in a positive (optimistic) or a negative (pessimistic) way. We investigated how the early hatchery experiences affects "optimism" and "pessimism". Commercially hatched chicks were exposed to a positive cue, an aversive cue, and ambiguous cues, in order to evaluate the cognitive welfare state of the animals. These chicks were compared to a group of non-stressed animals. Commercially incubated chicks did not have elevated levels of feather corticosterone, which implies that the main part of the stress effects from the hatchery originates from the period around hatch. Latencies to approach ambiguous cues were longer for the stressed chicks, i.e., these showed a more pessimistic-like behaviour. We conclude that the main part of the stress effects in commercially hatched chicks originates in the period around hatch, and further, that these birds show lasting levels of increased pessimism. This strongly indicates a long-time poorer welfare state for the animals. Worldwide, billions of laying hen chicks are incubated and processed under highly industrialised circumstances every year, which, as we have previously shown, has long-lasting effects. Here, we measured corticosterone incorporated in down feathers to investigate possible stress during the incubation and showed that commercially incubated chicks did not have elevated levels of feather corticosterone, which implies that the main part of the stress effects from hatchery originates from the perinatal period and the handling immediately post-hatch. Further, we investigated how the early hatchery stress affects the chicks cognitive welfare state, i.e., "optimism" and "pessimism". We exposed commercially hatched chickens to a positive cue, an aversive cue and ambiguous cues. The birds were tested at 1 and 10 w of age and the behaviour was compared with that of non-stressed chicks. Latencies to approach ambiguous cues were longer for the stressed chicks, both at 1 (p = 0.008) and at 10 (p = 0.020) weeks of age, i.e., these showed a more pessimistic-like behaviour. We conclude that the main part of the stress effects in commercially hatched chicks originates in the perinatal period, and further, that these birds show lasting levels of increased pessimism. This strongly indicates a long-time poorer welfare state for the animals.
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| 4. |
- Gabrielle, Lunden, et al.
(författare)
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Play ontogeny in young chickens is affected by domestication and early stress
- 2022
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Ingår i: Scientific Reports. - : NATURE PORTFOLIO. - 2045-2322. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Play is common in young homeotherm animals and has an important role as a tentative indicator of positive states of welfare. Furthermore, during domestication play is believed to have increased in frequency in several species as part of the domestication syndrome. Here, we studied the ontogeny of play in chickens in two experiments. The first compared the behavioural development between domesticated White Leghorn (WL) laying hen chicks and ancestral Red Junglefowl (RJF) and the second compared the same between WL chicks that had experienced the stress of commercial hatchery routines and a control group, hatched under calm conditions. In both experiments, 10 groups of four chicks each from each of the groups were moved twice per week to an enriched and fully enclosed play arena, starting at day 8 and finishing day 39 or 53 after hatch. In the arena, the frequency of play behaviours was recorded during 30 min and divided into object, locomotory and social play. In experiment one, total play as well as object play was significantly more common in WL whereas locomotor and social play was more common in RJF. In experiment two, total play was significantly more frequent in commercially hatched chicks, despite that none of the sub-categories differed significantly between the groups. In conclusion, domestication as well as early stress does affect the occurrence of play in chickens, but the effects are complex and require further research.
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| 5. |
- Hedlund, Louise, 1987-
(författare)
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Effects of commercial hatchery processing on behaviour and welfare of laying hens
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Around the world, more than 76.7 million tons of eggs are consumed every year. To meet this demand, billions of laying hen chicks are produced under highly industrial circum-stances. These chicks are hatched in commercial hatcheries for laying hens in a presumably stressful environment, which might affect their welfare and production later in life. When the eggs arrive to the hatchery, they are inserted in large cabinet incubators that can hold approximately 60 000 eggs. The incubators are calibrated for optimal hatchability which includes turning of the eggs as well as fluctuating temperature and humidity over the day. This is regulated by fans whose purpose consists of removing heat and circulating the air in the incubators. However, the drawback of these fans is that their noise levels exceed 90 dB, which is equal to the sound of a passing train. After 19 days, the eggs are moved to a hatcher for the last days of incubation, in which they are exposed to formaldehyde for disinfection purposes. The eggs hatch after 21 days of incubation but are kept in the hatcher for an additional day to maximize hatchability rate. After removal from the hatcher, the racks with chicks are tilted onto a conveyer belt and separated from the shells. The chicks are then conveyed to a sex-sorting station where the males are dis-carded, and the females are further processed to a vaccination station. Once vaccinated, the animals are automatically counted and packed in transport boxes which are loaded onto a truck and transported to rearing farms. The aim of this thesis was to investigate if and how the chickens are short- and long-term affected by this hatchery procedure, including incubation and transportation, and how this might affect their welfare. In all experiments, we have compared commercial hatchery incubated, hatched, processed, and transported White Leghorn chicks (hatchery chicks, HC) with chicks incubated and hatched in a calm environment, and gently placed in their home pens directly after hatch (control chicks, CC). In all experiments, HC and CC were from the same parental stock and kept in separate but identical pens. In paper I, we blood sampled the chicks before and after the hatchery handling to evaluate stress hormone levels (CORT) in the hatchery. The HC had significantly higher CORT levels than the CC had at a corresponding time point, which implies that the hatchery treatment is a highly stressful experience. Our results of behaviour, HPA-axis sensitivity, and feather damages showed that the commercial hatchery treatment has a long-lasting overall negative effect on the animals up to at least 20 weeks of age. In paper II, we aimed to compare chicks incubated, hatched, and sorted at the hatchery, with chicks incubated and hatched at the hatchery who were not sorted, to distinguish the stress effects of the actual conveying and handling. We could not find any major differences between the groups and concluded that the most stressful part in the commercial hatchery seems to be the incubation and hatching, potentially due to the high noise levels and formaldehyde exposure. In paper III, we investigated possible welfare implications of the hatchery procedure by using a cognitive judgement bias (CJB) test that is used to measure optimism/pessimism in animals. In general, pessimistic animals perceive the same environment as more negative than optimistic animals, hence, this has a great impact on their welfare. When testing HC and CC in a CJB test, we could see that HC were consistently more pessimistic than CC, during 1st, but also during 10th week of age. This means that the hatchery treatment has a long-lasting effect on the cognitive state of the animals, implying the animals exposed to this have a poorer welfare. In paper IV, we investigated possible effects of the hatchery treatment on production parameters. We found that HC weighed less, and laid fewer and smaller eggs than CC. HC performed more feather pecking behaviour before sexual maturity, although the feather condition after sexual maturity showed the opposite pattern. We conclude that there seems to be an effect of the hatchery treatment on traits relevant for the industry, and that this effect seems to be overall negative. In the last study, paper V, we investigated if it is possible to buffer the hatchery stress with environmental enrichment. The enriched chicks were kept in a complex environment and imprinted on, and provided with, a stuffed mother hen. We could see a supressed physiological stress reaction to restraint in enriched HC, however, the opposite pattern was shown in CC. We found no other effects of environmental enrichment, how-ever, an overall difference between the groups where HC were more pessimistic and fearful than CC, which is in line with our previous results. In conclusion, the hatchery procedure including incubation, hatching, conveying, sex sorting, vaccination, and transport seems to have an overall long-lasting negative effect on chicks, where HC are more fearful and pessimistic, have a more sensitive HPA-axis, show more feather pecking behaviour, and are negatively affected with regard to traits relevant to the industry. I think that these results are highly relevant, not only for the industry, but also for the welfare of the world’s most common farm animal.
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| 6. |
- Ericsson, Maria, et al.
(författare)
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Domestication and ontogeny effects on the stress response inyoung chickens (Gallus gallus)
- 2016
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Ingår i: Scientific Reports. - London : Nature Publishing Group. - 2045-2322. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Domestication is thought to increase stress tolerance. The connection between stressor exposure,glucocorticoids and behavioural responses has been studied in adults, where domestication effectsare evident. Early stress exposure may induce detrimental effects both in short-and long term.Previous research has reported a lack of glucocorticoid response in newly hatched chickens (Gallusgallus), whereas others have found opposite results. Hence it remains unclear whether the HPA-axis isfunctional from hatch, and if domestication has affected the early post-hatch ontogeny of the stressresponse. Our aims were to investigate the early ontogeny of the HPA-axis and characterize behaviouraland hormonal stress responses in ancestral Red Junglefowl and in two domestic layer strains. Plasmacorticosteone and behavioural responses before and after physical restraint was measured on dayone, nine, 16 and 23 post hatch. The results showed significant increases of corticosterone after stressin all three breeds at all the different ages. The HPA-response decreased with age and was lower inRed Junglefowl. Behavioural responses also decreased with age, and tended to be stronger in RedJunglefowl. In summary, the HPA-axis is reactive from day one, and domestication may have affectedits development and reactivity, alongside with related behaviour responses.
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| 7. |
- van Poucke, Enya, et al.
(författare)
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Commercial hatchery processing may affect susceptibility to stress in laying hens
- 2023
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Ingår i: PLOS ONE. - : PUBLIC LIBRARY SCIENCE. - 1932-6203. ; 18:9
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Tidskriftsartikel (refereegranskat)abstract
- Directly upon hatching, laying hen chicks are exposed to multiple stressful events during large-scale hatchery processing, which may affect their later coping abilities. Commercial hatchery chicks (HC) were compared to chicks that were incubated and hatched simultaneously under calm conditions (CC). After being raised under similar, non-stressful conditions for 36 days, all chicks were exposed to a series of stressors: transportation and introduction into a novel environment followed by a regrouping event in order to characterize long-lasting consequences of hatchery treatment. Tonic immobility, corticosterone levels, and peripheral body temperature were used to assess reactions to the stress events. Tonic immobility was not affected by treatment but was significantly reduced in CC after transport. Corticosterone levels did not differ between treatments when assessed two days before and two days after regrouping. Comb temperature was significantly higher in HC following regrouping, indicating stress-induced hyperthermia. Furthermore, comb temperature dropped more following blood sampling in HC than in CC, indicating a stronger autonomic response to acute stress. In conclusion, the results suggest possible long-term negative effects of commercial hatchery processing, compared to hatching under silent and less stressful conditions, on the coping ability of laying hens to later stressful experiences.
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| 8. |
- Håkansson, Jennie, et al.
(författare)
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Behavioural differences between two captive populations of red junglefowl (Gallus gallus) with different genetic background, raised under identical conditions
- 2007
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Ingår i: Applied Animal Behaviour Science. - : Elsevier BV. - 0168-1591 .- 1872-9045. ; 102:1-2, s. 24-38
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Tidskriftsartikel (refereegranskat)abstract
- Ex situ conservation of threatened species may lead to behavioural adaptation, which can affect success of reintroduction attempts. In previous studies, we investigated the effects of captivity on the behaviour of red jungle fowl (Gallus gallus) and found that captive populations differed behaviourally as well as genetically. The aim of the present study was to compare the behaviour of two of the previously studied populations, raised under identical conditions. Eggs were collected from birds at Copenhagen zoo (Cop) and Götala research station (Got) and were incubated and hatched together. Twenty-eight birds (16 Got and 12 Cop) were reared together and tested in eight different behavioural tests, measuring different aspects of fear-related behaviours as well as exploratory and social behaviours. The study revealed several differences in fear-related behaviours between the populations but none in exploratory or social behaviours. In general, one of the populations (Cop) showed more intense fear behaviours than the other (Got), which instead were less fearful in their behaviours. This indicates that breeding animals in captivity may lead to behavioural modifications, which can affect the outcome of reintroductions. The results further suggest that fear-related behaviours are dependent on the genetic background of the animals while social behaviours may be more influenced by the social environment. Since fear-related behaviours, such as predator avoidance and fear of humans, are essential for a life in the wild, these aspects are crucial for the breeding of animals in captivity for conservation purposes.
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| 9. |
- Håkansson, Jennie, et al.
(författare)
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A longitudinal study of antipredator behaviour in four successive generations of two populations of captive red junglefowl
- 2008
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Ingår i: Applied Animal Behaviour Science. - : Elsevier BV. - 0168-1591 .- 1872-9045. ; 114:3-4, s. 409-418
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Tidskriftsartikel (refereegranskat)abstract
- Conservation breeding and reintroduction into the wild can only be an effective management tool if behaviours essential for a life in the wild are maintained in captivity. The aim of this study was to investigate how a protected captive environment influences antipredator behaviour over generations. The red junglefowl (Gallus gallus) was used as a case study. Birds from two different captive populations were followed over four generations. In the last three generations, all birds were hatched and reared in the same indoor settings. Antipredator behaviour was measured in each generation in a standardised test where the birds were exposed to a simulated predator attack. The test was divided into three parts: pre-exposure period, exposure and post-exposure periods. There was an interaction effect between Population and generation (F-3.129 = 4.84, P < 0.01) on behaviour during the pre-exposure period, suggesting that the birds "baseline" agitation level may have been altered differently in the two populations. Population differences were also found during the post-exposure period but the populations tended to become more similar over successive generations in their behaviour after the exposure. Furthermore, there were significant effects of generation (H (d.f. = 1, N = 137) = 10.94, P < 0.05) as well as population (H (d.f. = 1, N = 137) = 5.17, P < 0.05) on the immediate reaction to the simulated predator attack. In conclusion, over four successive generations, the two populations altered their antipredator behaviour and tended to become more similar. This study shows that antipredator behaviour may change over generations in a captive environment. This is likely to be one of the most crucial factors for successful reintroduction into the wild and hence, it is a very important aspect to consider for conservation breeding.
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| 10. |
- Lötvedt, Pia, et al.
(författare)
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Effects of Hatching Time on Behavior and Weight Development of Chickens
- 2014
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Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 9:7, s. e103040-
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Tidskriftsartikel (refereegranskat)abstract
- The length of the embryonic period varies both among and within species and can affect the individual phenotype in many ways, both physiologically and behaviorally. In chickens, the hatch window may last 24-48 hours (up to 10% of the incubation time), and studies have shown that incubation length may affect post-hatch growth and physiology. However, little is known about effects on behavior. We therefore investigated how behavior variation correlates with hatching time in the early life of chickens. We also measured egg weight and egg weight loss in relation to hatching time, as well as post-hatch growth. For females, there was a negative correlation between hatch time and body weight from day 4 and throughout the experiment. For males, such a correlation was only observed when testing all hatched males up until day 10. The birds were exposed to a number of behavioral tests, and a principal components analysis was performed on the variables, resulting in four components. For the largest component, termed "Passivity, a tendency of a difference was found between early and middle male hatchers. Furthermore, a significant difference between early and middle male hatchers was found in the second component, termed "Response to novelty. In a spatial learning test, late hatchers tended to learn slower. The behavior of females was not significantly affected by hatching time in any of these tests. This study is among the first to demonstrate a link between time of hatching and early behavior in a precocial species like the chicken, and may help shedding light on the evolutionary trade-offs between incubation length and post-hatch traits. The results may also be relevant from a perspective of stress coping and therefore also for animal welfare and productivity in the chicken industry. The mechanisms linking hatching time with post-hatch phenotype remain to be investigated.
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