Meat hygiene research

The study evaluated the impacts of alternative post mortem inspection regimes for tuberculosis in cattle presented for slaughter in New Zealand relative to current practices. A retrospective analysis of slaughterhouse post mortem data collected from M. bovis infected animals was conducted and then a model which accurately simulated the current observed lesion prevalence was developed. It was found that approximately 50% of tissues could be dropped from the examination with only a 2% loss of sensitivity. A group of “operationally relevant” tissues could be dropped with only a 1% loss of sensitivity.

keywords: Bovine tuberculosis, lymph nodes, post mortem examination

This project describes a scientific evaluation of the likely contribution of routine post mortem examination of tissues of the bovine carcass and viscera.

The current bovine post mortem procedures in New Zealand for the examination of the gall bladder, pericardium, penis and reticulum were scientifically evaluated as to their contribution to food safety. A risk profiling approach demonstrated that the following changes to current procedures would not affect food safety outcomes: no examination of the gall bladder, examination of the pericardium included within viewing of the heart, examination of the penis when saved as for human consumption by viewing and examination of the reticulum by viewing during examination of the gastro-intestinal tract.

This is a summary NZFSA report on the proposed post mortem examination procedures for the carcasses and viscera of adult sheep slaughtered in New Zealand. It provides an effective set of procedures that will continue to provide an equivalent level of performance for detection and removal of abnormalities of food safety and suitability importance. This set of procedures will also mitigate against any inadvertent cross
contamination with zoonotic pathogens that might result from unnecessary carcass handling.

Twenty three of the thirty establishments visited can readily meet the presentation requirements and accept the need for the changes.

The Meat Industry Association stated in its 2005 presentation to the NZFSA Verification Agency that one of the strategic goals of the meat Industry in Towards 2006 is…..” To be at the forefront of international food safety.” This goal is thoroughly supported by NZFSA and is unarguably an approach that will assist New Zealand in maintaining its deserved reputation as the world’s largest exporter of sheep-meat of the highest quality

The production of sheep and lamb meat is a significant part of the economy of New Zealand. Technological advances over many years have enhanced the efficiency, productivity and hygiene of sheep meat production, none more so than the introduction of inverted dressing (Longdell, 1992) where the de-pelting operation starts at the cleaner end of the carcass, and the pelt is moved downwards towards the rear, more contaminated, end.

Following on from the PFGE report of isolates to the end of 2008 (PFGE Typing of Meat
Isolates of E. coli O157:H7 in New Zealand; ESR, March 2009), this report describes the
results of PFGE analysis of an additional 55 E. coli O157:H7 isolates from meat received by ESR to 1 October 2009, and includes nine isolates associated with the
AgResearch/AsureQuality “Investigating E. coli O157:H7 False Positives” project.

From March to September 2006, 25 isolates were uploaded to the PulseNet USA E. coli O157:H7 pulsed field gel electrophoresis (PFGE) database with the XbaI:BlnI pattern EXHX01.0074:EXHA26.0569. Although this pattern is relatively common in the US database, this number of isolates suggests a potential common source outbreak. USDA-FSIS found E. coli O157:H7 isolates from two meat-processing plants with two similar XbaI:BlnI patterns (EXHX01.0074:EXHA26.0569 and EXHX01.1401:EXHA26.0569). One common link between these meat-processing plants is that both sourced some of their meat from New Zealand.

The molecular typing by PFGE has now been completed on all E. coli O157:H7 isolates
from young calves, bovine, veal, prime beef, and human cases included in the 2006 PFGE
Emergency Response typing project as well as prime beef and veal isolates submitted to
ESR up to July 24th 2008. The PulseNet Aotearoa (New Zealand) E. coli database contains
723 NZ E. coli O157:H7 isolates, including 411 human, 189 meat, 118 animal, and 4
environmental isolates.

An independent single laboratory study was performed by AsureQuality Auckland Laboratory to revalidate Escherichia coli O157:H7 screen kits following method amendments to the sample size and enrichment procedures in the New Zealand Food Safety Authority (NZFSA) E. coli O157:H7 monitoring programme for red meat.

The purpose of a Risk Profile is to provide contextual and background information relevant to a food/hazard combination so that risk managers can make decisions and, if necessary, take further action. The place of a risk profile in the risk management process is described in “Food Administration in New Zealand: A Risk Management Framework for Food Safety” (Ministry of Health/Ministry of Agriculture and Forestry, 2000). Figure 1 outlines the risk management process.

This document describes a scientific evaluation of the likely contribution of routine post
mortem examination of selected lymph nodes of cattle slaughtered in New Zealand to
food safety and to food suitability. Currently all carcass lymph nodes are required to be
examined by intensive examination while the mesenteric lymph nodes are examined by
viewing and palpation. In addition to questions over food safety aspects, there is scientific consensus that intensive routine examination of lymph nodes is likely to increase crosscontamination of some tissues.