Projects per year
were obtained in the laboratory using selective cultivation methods and log transformed to obtain a Gaussian distribution. Initially, the effect of the vaccine was analyzed using all data in a t-test. Subsequently, the t-test was stratified by rotation. Finally, mixed linear models were used, taking into account the physical hierarchical setup of the trial. Results from the t-test indicate an effect of the vaccine, whereas the result obtained from the complex model indicated high variability between birds and isolators but not significant vaccine effect. The apparent observed differences between vaccinated and placebo groups in the t-tests could be attributed to the variation between incubators. Broilers in the same isolator had more equal numbers of C. jejuni compared to chickens in other incubators. It is possible that chickens in the same isolator re-infect each other with Campylobacter. In this study, the design effect was considerable, reducing the effective sample size (67 animals instead of the 290 animals included). The clustered design used in this trial was trying to emulate the clustering effect found in broiler flocks and farms.
|Title of host publication||Book of Abstracts of the 13th International Symposium on Veterinary Epidemiology and Economics|
|Number of pages||1|
|Publisher||Wageningen Academic Publishers|
|Publication status||Published - 2012|
|Event||13th Conference of the International Society for Veterinary Epidemiology and Economics - Maastricht, Netherlands|
Duration: 20 Aug 2012 → 24 Aug 2012
Conference number: 13
|Conference||13th Conference of the International Society for Veterinary Epidemiology and Economics|
|Period||20/08/2012 → 24/08/2012|
Bibliographical notePoster 50
Hoorfar, J., Madsen, M., Bang-Berthelsen, I., Christensen, L. S., Josefsen, M. H., Vigre, H., Garcia Clavero, A. B., Saunders, I., Darsley, M., Lund, M., Sandøe, P., Wagenaar, J., Joens, L., Cooper, K., Madsen, A., Hald, B., Bahrndorff, S. & Heegaard, P. M. H.
01/03/2010 → 31/12/2014