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Worldwide, especially in Europe, poultry industry is undergoing important changes including ban of the battery housing system and prohibition of beak trimming. The former can facilitate more spread of infectious diseases, and the latter will contribute to higher mortality because of severe feather pecking. Furthermore, given the growing social concern about food safety and human health, abundant use of antibiotics will either be prohibited or restricted. These changes further emphasize the importance of implementing general disease resistance in layers breeding goals next to maintaining high production. The aim of this thesis was to find proper traits which are associated with laying hens survival, and reveal genetic architecture and background underlying the traits. Natural antibody (NAb), which are the antibodies present in normal healthy animals in the absence of a deliberate antigen exposure are an important humoral part of innate immunity. The relationships between survival and NAb isotype titers were firstly investigated by the logistic regression analysis in a population of laying hens from 12 purebred lines. The results indicated that NAb, especially the IgM isotype titers at young age was predictive for survival of a laying period. Genetic parameters of NAb isotypes IgM and IgG titers were estimated in the same population. The estimation showed that both NAb isotypes are moderate to high heritable traits which were possible to breed for. An association study revealed different QTL or SNP markers for NAb isotypes titers. The majority of the commercial laying hens are crossbred. Therefore, the relationships between NAb isotype titers and survival were further investigated in crossbred laying hens. However, a consistent relationship as in the purebred was not found. This confirmed the speculation that non-health-related causes of mortality (severe feather pecking) overruled the anticipated relationships between NAb isotype titers and survival in birds with intact beaks. Overall, the present studies indicate that it is possible to implement NAb especially the IgM isotype titers into the breeding goals of laying hens to improve the health-related survival.
|Qualification||Doctor of Philosophy|
|Award date||7 Oct 2013|
|Place of Publication||S.l.|
|Publication status||Published - 2013|
- genetic analysis
- genetic parameters
- feather pecking
- animal breeding
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- 1 Finished
Sun, Y., van Arendonk, J. & van der Poel, J.
1/09/09 → 7/10/13