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Welfare indicators in laying hens

Alm, Malin (2015). Welfare indicators in laying hens. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis agriculturae Sueciae, 1652-6880 ; 2015:50
ISBN 978-91-576-8298-7
eISBN 978-91-576-8299-4
[Doctoral thesis]

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Abstract

There is a growing concern regarding the welfare of laying hens worldwide and there are both ethical and economic reasons for improving their welfare. Although several different welfare indicators are used today, their ability to accurately reflect welfare status is sometimes questioned. This thesis sought to increase knowledge regarding a number of these welfare indicators by investigating whether and to what extent they were affected when layers were exposed to different stressors. Three different commercial laying hen genotypes were used and birds were challenged by being excluded either from their nests in furnished cages or from the litter area in a single-tier floor system.

Excluding birds from their nests resulted in an increased stress response that was detectable in corticosterone metabolites in droppings, corticosterone concentration in egg yolk, heterophil to lymphocyte ratio and egg shell irregularities. Excluding birds from the litter area during the first two weeks in the laying facility resulted in differences in feather cover, approaches towards a novel object, tonic immobility duration and egg shell irregularities measured later in the laying period. Interestingly, according to the welfare indicators used, birds previously excluded from the litter area, and consequently deprived of litter and available area, had better welfare than non-excluded birds. In addition, levels of corticosterone metabolites in droppings were influenced by factors such as diet, genotype, bird age, cage tier, droppings mass, time of day and the kind of assay used.

The results showed that several, but not all, indicators were able to detect different stress responses, suggesting that they are more or less appropriate to use depending on the situation prevailing. Many factors influenced the results obtained and there were few and inconsistent correlations, displaying a complex relationship between indicators. Overall, this indicates that welfare assessment should preferably be based on results from several indicators and that careful interpretation of the results is required before stating firm conclusions regarding laying hen welfare.

Authors/Creators:Alm, Malin
Title:Welfare indicators in laying hens
Series/Journal:Acta Universitatis agriculturae Sueciae (1652-6880)
Year of publishing :2015
Depositing date:7 May 2015
Volume:2015:50
Number of Pages:71
Papers/manuscripts:
NumberReferences
IAlm, M., Holm, L., Tauson, R. and Wall, H. (2014). Corticosterone metabolites in laying hen droppings- Effects of fiber enrichment, genotype, and daily variations. Poultry Science 93, 2615-2621.
IIAlm, M., Tauson, R., Holm, L., Wichman, A., Kalliokoski, O. and Wall, H. A comparison of potential welfare indicators measured in laying hens in relation to nest exclusion (manuscript).
IIIAlm, M., Wall, H., Holm, L., Wichman, A., Palme, R. and Tauson, R. (2015). Welfare and performance in layers following temporary exclusion from the litter area on introduction to the layer facility. Poultry Science 94, 565-573.
Place of Publication:Uppsala
Publisher:Department of Animal Nutrition and Management, Swedish University of Agricultural Sciences
ISBN for printed version:978-91-576-8298-7
ISBN for electronic version:978-91-576-8299-4
ISSN:1652-6880
Language:English
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:L Animal production > L01 Animal husbandry
L Animal production > L70 Veterinary science and hygiene - General aspects
Subjects:(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 402 Animal and Dairy Science > Animal and Dairy Science.
Agrovoc terms:layer chickens, animal welfare, indicators, stress, corticosterone, feathers, egg shell, leukocytes, lymphocytes, behaviour, egg production
Keywords:laying hens, welfare indicators, stress, corticosterone, feather cover, tonic immobility, novel object, H/L ratio, egg shell irregularities, behaviour, production
URN:NBN:urn:nbn:se:slu:epsilon-e-2632
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-e-2632
ID Code:12186
Faculty:VH - Faculty of Veterinary Medicine and Animal Science
Department:(VH) > Dept. of Animal Nutrition and Management
Deposited By: Malin Alm
Deposited On:08 May 2015 10:38
Metadata Last Modified:08 May 2015 15:06

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