Schlüsselwörter
(Deutsch)
|
Tierschutz, Legehennen, Federpicken, Stress, Immunreaktion, tonische Immobilität, Lymphocyten
|
Schlüsselwörter
(Englisch)
|
Animal welfare, Feather pecking, stress, immune response, tonic immobility, Heterophil / Lymphocyte ratio, laying hens, Gallus gallus domesticus
|
Kurzbeschreibung
(Englisch)
|
A total of 224 individually marked laying hens will be used. They are raised by a commercial breeder and checked that they do not show feather pecking during the rearing period. With 18 weeks the hens are randomly assigned to 16 idnetical pens. We are then imitating the effects of stress by administration corticosterone ( Siegel 1980; Mashaly et al. 1984; Craig & Craig 1985; Saterlee et al. 1989). Different amounts of corticosterone are added to the feed in order to induce physiological changes similar to those of chronic stress (Gray et al 1989). The observed alterations on the behavioral and physiological level are interpreted as ractions to chronic stress. Feather pecking and tonic immobility (Mills & Faure 1986) are selected as behavioural parameter. Data collection an feather pecking wfill start in week 19 and be completed in week 24. Subsequent, tonic immobility reaction will be mesured. As a physiological parameter heterophil-lymphocyte ratio in the blood (Gross & Siegel 1983) will be determined in week 26. Data on egg output and body weight as parameters representing production are collected from week 19 to week 24. The effects of stress on humoral and cell-mediated immune responses are measured in week 26 to 29. The humoral immune response to novel antigens is quantified and the expression of in-vivo cell-mediated immunity is evaluated by using simple skin testin: Delayed hypersensitivity reaction (Cockram et al. 1993) elicted by purified protein derivative and cutaneous basophilic hypersensitivity reaction elicted by phytohaemagglutinin-p (Stadecker te al. 1997; Edelman et al. 1985) will be determined. At the end of the experiment the hens are sold to commercial poultry farmers.
|
Projektziele
(Englisch)
|
In an earlier experiment (El-lethey et al., submitted) we were able to show a positive correlation between feather pecking and stress as measured by the heterophil/lymphocite ration and tonic immobility reaction. The present experiment aims at extending this result by studying the question whether feather pecking is a consequence of stress or vice versa. Additionally the study will look in more detail at the correlation that was found in the former study between stress and the response of the immune system by investigating the effect of stress on both humoral and cell-mediated immune response.
|
Abstract
(Deutsch)
|
siehe in englischer Sprache
|
Abstract
(Englisch)
|
Birds fed on corticosterone had reduced values for weight gain and egg production, prolonged TI, higher H/L ratios and higher serum corticosterone concentrations. All indicating that feeding corticosterone did indeed induce stress in the birds. The so stressed birds developed significantly higher rates of feather pecking than birds not fed corticosterone, when kept on litter. Birds kept on slats developed higher rates of feather pecking without being fed corticosterone. Feeding corticosterone to these birds on slats did not significantly further increase the rates of feather pecking. It is concluded that feather pecking may develop as a response to stress mediated through increased corticosterone levels, but that housing conditions restricted in relation to foraging material may also induce feather pecking without increasing serum corticosterone levels.
|
Publikationen / Ergebnisse
(Englisch)
|
El-lethey, H.S.E. (2000): Influence of stress on feather pecking and immune response in laying hens. Thesis of the Veterinary Faculty of the University of Berne.
El-lethey, H., Jungi, T.W., Huber-Eicher, B. (2001): Effects of feeding corticosterone and housing conditions on feather pecking in laying hens (Gallus gallus domesticus). Physiologiy and Behaviour 73: 243-251.
El-Lethey, H., Huber-Eicher, B., Jungi, T.W. (2003): Exploration of stress-induced immunosuppression in chicken reveals both stress-resistant and stress-susceptible antigen responses. Veterinary Immunology and Immunopathology 95: 91 - 101.
|
