Auswirkung der Schlachtung unterschiedlich stark verschmutzter Rinder auf die mikrobiologische Belastung ihrer Schlachtkörper

Episode von Tierärztliche Fakultät - Digitale Hochschulschriften der LMU - Teil 07/07 von Ludwig-Maximilians-Universität München · 12. Juli 2014

Hide contamination represents a main source of microbiological contamination of carcass surface. In order to reduce the potential health risks for the consumer the EU implemented measures in the context of the regulations no. 852/-, 853/- and 854/2004. These imply that only clean cattle are suitable for slaughter in order to eliminate the risk of meat contamination via hide or skin. Food business operators are responsible for ensuring that the requirements are met. One problem is, that the meaning of cleanliness is not defined clearly enough. Therefore some European states implemented regulations for the grading of hide cleanliness.

The main objective of the own analysis was to point out the correlation between the level of hide contamination and the total bacteria count of the surfaces of the carcasses. Therefore an ascending hide cleanliness classification system for beef cattle was developed which is based on two vertical hide regions, an area measure as well as aspects of cleanliness and humidity based on three major-classes for hide-cleanliness. In total 180 female bovine cattle were classified by their hide, digitally photographed from four perspectives (two standing and two stunned) as well as slaughtered and examined in a group of equal or very similar level of conta- mination on test days.

The sampling technique was based on stalked sponge swabs, which were pulled over four exactly defined locations of the freshly flayed carcass twice (front and back side) through a self-developed oblong template measuring 100 cm2. The four incre- mental samples per animal were pooled and tested for the hygiene indicators aerobic colony count as well as for Enterobacteriaceae count and Escherichia coli count.

Analyzing the data set statistically all logarithmized aerobic colony counts were normally distributed. Three ordinal scores for aerobic colony count were defined (Score1:0bis≤2log10 cm-2,Score2:2bis≤ 3log10 cm-2 andScore3:>3log10 cm-2) and tested in conjunction with the three major classes of hide contamination. The general finding was that the amount of animals with low total bacteria count (Score 1) decreased with higher major class. The amount of cattle with moderate

Summary 119

bacteria content (Score 2) increased slightly with the major class. The amount of animals with high total bacteria count (Score 3) increased substantially with the major class. It could be shown that major-class-I included a statistically significant lower amount of animals with high total bacteria count compared to major-class-II. The same held for the comparison of major-class-II and -III as well as of major- class-I and -III. E. coli and Enterobacteriaceae could be evidenced only on about a third of the carcasses and thus be analyzed in combination with the major-classes and the three Scores. Applying the reduced population respectively the same correlation could be confirmed approximately.

Overall the described correlations can be taken as indication that the considered colony counts rise with an increasing visual level of contamination. In case of development and implementation of a regulation system in Germany the application of a maximum of three ascending classes of hide contamination appears to be justifiable. Furthermore the terms „clean“ and „cleanliness“ should be complemented with attributes as „sufficient(ly)“.

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