Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Evaluation of the " testing and scheduling" strategy for control of Campylobacter in broilers in The Netherlands
    Nauta, M.J. ; Wal, F.J. van der; Putirulan, F.F. ; Post, J. ; Kassteele, J. van de; Bolder, N.M. - \ 2009
    International Journal of Food Microbiology 134 (2009)3. - ISSN 0168-1605 - p. 216 - 222.
    quantitative risk-assessment - real-time pcr - cross-contamination - chicken carcasses - poultry carcasses - spp. - numbers - quantification - prevalence - chain
    “Testing and scheduling” has been proposed as a strategy for control of Campylobacter in broiler meat. By this strategy, flocks with high numbers of Campylobacter in fecal samples would be diverted away from fresh meat production at the entrance of the broiler meat processing plant. Risk assessment studies suggest that this would effectively decrease human health risks, if these flocks are responsible for the meat products with the highest Campylobacter numbers. To investigate the effect of this control strategy, the numbers of Campylobacter were determined in fecal samples from transport containers, and in cecal and breast meat samples from birds in 62 broiler chicken flocks. Results from direct plating and enrichment were combined by a statistical method that allows the inclusion of censored data. As the implementation of “testing and scheduling” requires a rapid on-site test to detect high numbers of Campylobacter, a lateral flow immuno-assay (LFA) was developed and applied to the fecal samples collected from containers. The Campylobacter prevalence in broiler flocks in the autumn of 2007 was found to be 85.4% by traditional microbiological methods. Campylobacter could be isolated from breast meat samples from 42% of the flocks. There was limited agreement between Campylobacter results for the three types of samples and weak correlation between the quantitative results for fecal or cecal samples and meat samples. Agreement between the results of LFA and traditional methods was poor. These findings do not support the implementation of “testing and scheduling” as a practical control strategy, because of both measurement uncertainties and shortcomings in understanding the dynamics of transmission and survival of Campylobacter in the broiler meat processing plant. The limited correlation between Campylobacter contamination of cecal samples and breast meat samples, as observed in this study, suggests that cecal samples are no good indicator for human exposure to Campylobacter.
    Shadow Price Approach to Total Factor Productivity Measurement: With an Application to Finnish Grass-Silage Production
    Kuosmanen, T.K. ; Post, T. ; Sipiläinen, T. - \ 2004
    Journal of Productivity Analysis 22 (2004)1-2. - ISSN 0895-562X - p. 95 - 121.
    fisher ideal indexes - industrialized countries - technical progress - efficiency change - growth - numbers
    This paper explores an intermediate route between the Fisher and the Malmquist productivity indexes so as to minimize data requirements and assumptions about economic behavior of production units and their production technology. Assuming quantity data of inputs and outputs and the behavioral hypothesis of allocative efficiency, we calculate the exact value of the Fisher ideal productivity index using implicit shadow prices revealed by the choice of input-output mix. The approach is operationalized by means of a nonparametric data envelopment analysis (DEA) model. Empirical application to Finnish grass silage farms suggests that the Malmquist and the Fisher productivity indices yield similar results when averaged over firms, but there can be major differences in the results of the two approaches at the level of individual firms.
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