| Registro completo |
| Provedor de dados: |
Organic Eprints
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| País: |
Germany
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| Título: |
Animal welfare in organic egg production - Emphasis on Mortality and Helminth Infections
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| Autores: |
Hinrichsen, Lena Karina
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| Data: |
2015-03-10
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| Ano: |
2015
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| Palavras-chave: |
Health and welfare
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| Resumo: |
The consumers’ motivation to buy organic products includes animal welfare aspects, and even though the retail market share for organic eggs in Denmark is relative high, there are a number of welfare issues in the organic egg production compared to other production systems, like higher mortality and prevalence of helminth infections, that are not in agreement with the consumers’ expectation. The aim of this PhD study was to investigate animal welfare in organic egg production in Denmark, with emphasis on mortality and helminth infections. The specific hypothesis in the PhD study were i) helminth infections (Ascaridia galli and Heterakis sp.) increase the mortality rate at peak of lay (observational event study, Paper I), ii) helminth infections (Ascaridia galli and Heterakis sp.) diagnosed at end of lay can be predicted by at least one clinical welfare indicator diagnosed at peak of lay and end of lay (longitudinal study, Paper II). Moreover, iii) it is possible, based on qualitative interviews, to identify management strategies for maintaining low mortality and controlling endoparasite (mainly helminth) infections (qualitative interview study, Paper III). Data were obtained from three studies conducted at 15 commercial Danish organic egg farms, and the results are presented in three scientific papers. In the first study (Paper I), weekly mortality rates were related to level of infection with A. galli and Heterakis sp. using survival analysis, and the study included 11 commercial organic egg farms, representing 15% of the Danish organic layers. An association was found between the A. galli and Heterakis sp. infection level and mortality rates. Low-infected farms (mean ≤200 eggs per gram of faeces (EPG)) had similar mortality rates in summer and winter; therefore, all low-infected farms despite of season were used as reference in the analysis. The mortality rate was twice as high for highly-infected farms (mean > 200 EPG) observed in summer compared to low-infected farms, whereas highly-infected farms observed in the winter did not have a significant different mortality rate compared to low-infected farms. Consequently, hypothesis i) was confirmed in relation to observations during summer, but not for observations during winter. The second study (Paper II) included 214 individual hens from 12 farms assessed twice during the production period (at peak and end of lay) to investigate if helminth (A. galli and Heterakis sp.) infection can be predicted by clinical welfare indicators, like the condition of the plumage, keel bone, skin, feet and comb. A graphical model displayed that helminth infections (A. galli and Heterakis sp.) diagnosed at the end of lay only were associated with back feathering at the end of lay. Hens with a good plumage condition at the back at the end of lay had a higher incidence of helminth infections than hens with a poor plumage condition at the back. Further, the study showed that the number of keel bone deformities increased and plumage conditions deteriorated between the two visits, whereas prevalence of bumble foot and pale combs decreased. Frequency of skin, feet and toe lesions did not differ significantly between the two visits. Therefore, hypothesis ii) was confirmed, as helminth infection could be predicted based on at least one clinical welfare indicator. However, in relation to daily management on commercials farms the relationship might not be useful. The third study (Paper III) investigated seven organic egg producers’ perception and experiences with maintaining a low mortality and controlling helminth infections using qualitative interviews. Four main causes of mortality were identified: predation, effect of weather, infectious diseases and smothering, and three themes important for maintaining low mortality were identified: pullet quality (uniformity and a good start-up at the egg production site), management and time (daily routines, time spent with the hens, and time for unforeseen matters), and feed (quality and quantity of feed and water). In relation to control of helminth infections, three practices were described by the producers: no testing of the infection level, regular testing of the infection level and irregular testing of the infection level. The two practices that included test of the infection level ended with deworming if it was considered necessary. The producers believed that management practices related to mortality had a positive effect on helminth infections and vice versa. Based on the results from the qualitative interviews hypothesis iii) was confirmed, as it was possible to identity management strategies for maintaining low mortality and controlling helminth infections. The overall findings of the PhD study report that control of helminth infections could potentially reduce the mortality and improve the welfare of hens with an otherwise good welfare in relation to plumage condition, as these hens have the highest incidence of helminth infection. However, the fact that the producers lack knowledge of alternatives to deworming strategies, which potentially could improve the animal welfare in the organic egg production, calls for further research on how to prevent helminth infections.
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| Tipo: |
Thesis
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| Identificador: |
http://orgprints.org/28857/7/28857.pdf
Hinrichsen, Lena Karina (2015) Animal welfare in organic egg production - Emphasis on Mortality and Helminth Infections. PhD thesis, Science and Tehnology, Department of Animal Science. Aarhus University.
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| Editor: |
Aarhus University
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| Relação: |
http://orgprints.org/28857/
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| Formato: |
application/pdf
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