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National Feed Inspection Program 2003-04
Report - Assessment of Microscopic Analysis as a Tool for Analysing Composition of Feed

Questions and Answers - Microscopy (Trial)

EXECUTIVE SUMMARY

The Canadian Food Inspection Agency (CFIA) designs and delivers inspection programs to provide a reasonable assurance of compliance by regulated parties and science-based mitigation of risks. As a matter of routine, CFIA explores opportunities for any incremental improvement in these programs. From January 1, 2004 to March 31, 2004,CFIA collected feed samples for a small microscopy trial to evaluate the utility of this technology as one indicator within a broader system of compliance checks. The following report describes a two stage assessment of microscopic laboratory analysis as a potential tool for analysing the composition of feed within the context of the CFIA’s BSE feed control program.

As a measure for animal health, the BSE feed restrictions were designed to reduce the spread of BSE within the cattle herd to a level that would result in eradication of the disease over time. The extent to which the feed controls minimize exposure of cattle to potentially infective feed determines the pace at which BSE will be eradicated from the animal population in Canada.

The results of the microscopy trial illustrate that the limitations of this laboratory technique outweigh its potential utility. For example, microscopy is not capable of differentiating between animal tissues that can enter the feed chain through the grain harvesting and feed distribution system (e.g., incorporation of small mammals or birds) from those that would present an animal health risk for BSE within the scope of Canada’s feed controls. In the end, it was necessary to rely on physical inspection of facilities and records, as is routinely done within the scope of the Agency’s ongoing inspection program.

Physical inspection of facilities and reports identified that the vast majority of samples did not contain prohibited material. In 11 domestically generated samples of the total of 110 samples (65 of which came from Canada), the CFIA was unable to rule out the possibility that some (likely incidental level of) prohibited material may have been among the animal tissues detected by microscopy. Given that microscopy is a limited tool in that it could not determine conclusively that there was no prohibited material in these samples, the CFIA has verified, where appropriate, that the establishments involved have enhanced their record keeping, flushing and/or sequencing practices in compliance with Canada’s BSE feed controls.

BACKGROUND

The food safety measure which protects Canadian consumers of beef from BSE risk is the requirement to remove specified risk materials (SRM) from all cattle slaughtered in Canada for human consumption. SRM are tissues such as brain and spinal cord that, in infected cattle, are capable of transmitting BSE. The animal health risk is addressed through restrictions on feeding certain proteins, including SRM, to cattle and other ruminant animals potentially susceptible to BSE.

Canada implemented its BSE feed controls in 1997 to reduce the potential spread of BSE, should it have already gained a foothold in North America at some undetected level. As an animal health measure, the feed controls prohibit the feeding of ruminant animals (e.g. cattle, sheep, goats, deer etc.) with animal proteins of mammalian origin (termed "prohibited material") with the following exceptions:

• proteins derived exclusively from porcine animals;
• proteins derived exclusively from equine animals;
• blood products from any species (including ruminants); and
• milk products from any species (including ruminants).

Limiting the potential spread of BSE among the animal population in this manner is expected to lead to the eradication of the disease over time. The relative degree to which the ban minimizes the exposure of cattle to potentially infective feed, determines the rate of decline of BSE in the cattle population and, therefore, over what period of time eradication may be achieved. No ban is one hundred percent airtight. Nevertheless, experience in the United Kingdom has demonstrated that the introduction of its ruminant-to-ruminant feed ban, even if imperfectly implemented, remains the single most effective measure taken to reverse the BSE epidemic in Europe. Results to date from progressively intensified and targetted surveillance testing for BSE in Canada continue to show that there is a low incidence of BSE in the Canadian cattle herd. This surveillance result is consistent with effective feed control measures.

The CFIA designs and delivers inspection programs that provide a reasonable assurance of compliance by regulated parties and mitigation of risks. In this case, Canada’s BSE feed controls were designed according to science-based international standards for animal health. In order to make its inspection programs as complete as possible, CFIA continually searches for new assessment tools to supplement established practices. This report describes an assessment of microscopic laboratory analysis as a tool for analyzing the composition of feed.

MICROSCOPY TRIAL

From January 1, 2004 to March 31, 2004, the CFIA collected feed samples for a small field trial to evaluate the potential usefulness of microscopic analysis of the composition of feed within its inspection program. The trial included distinct stages, the first of which involved laboratory analysis of feed samples using microscopy – that is, viewing microscopic sized particles of animal feed mounted on a glass slide. As a second stage, laboratory results were then reviewed with inspection reports for the feed manufacturing establishment from which the samples were taken. The intent was to determine the degree to which inferences could be drawn about the implementation of the feed ban using a combination of these two different information sources.

In stage one, the laboratory results by themselves were not intended to nor are they capable of determining compliance, or non-compliance, with the feed control measures. As such, the trial was undertaken by the CFIA with the understanding that microscopic analysis as a testing technique on its own has some significant limitations. It enables the detection of extremely small pieces of animal material (feathers, hair, muscle fragments, bone fragments, lactose and blood meal) generally, but it cannot be used to identify particular species or whole tissues (e.g. porcine versus ruminant meat and bone meal, or small mammals picked up during grain harvesting and feed distribution). Test results are qualitative in nature (the analyst reports what is seen, e.g., hair, muscle fragment) and cannot determine the origin or how much animal material might be in the feed. Therefore, the trial included microscopic analysis in combination with inspection activities so that the CFIA could better evaluate microscopic analysis as a non-specific screening tool for animal material.

Two categories of feeds were eligible for sampling :

• Feed ingredients (bulk or packaged ingredients that are commonly used in feeds for ruminants such as cereals and cereal byproducts, oilseed meals, grain screenings); and,
• Ruminant feeds (bulk or packaged complete feeds, supplements and macro-premixes for cattle, sheep, goats, deer, elk, bison etc.); formulations of ruminant feeds sampled were not intended to contain any animal protein products although formulations containing blood and milk products were acceptable.

DETAILED RESULTS AND ANALYSIS

A total of 110 samples of livestock feeds and ingredients were obtained by the CFIA inspection staff. At the time of sampling, inspection staff also conducted a brief inspection of the facility with the purpose of obtaining basic manufacturing information related to the sample and the facility where it was obtained. Of the 110 samples taken, 65 were of domestic origin and 45 of imported origin.

At stage one, a total of 43 samples reported no detection of animal material and there were 67 samples where a result of detected was reported for animal material. (Table 1).

Table 1: Stage One - Sample Results

Where the laboratory result did not detect the presence of any kind of animal material it was possible to conclude that the samples did not contain any prohibited material under the ban. Where animal material of any kind was detected, it was necessary to undertake further analysis beyond the laboratory in order to draw any meaningful conclusions.

Laboratory results which detected unspecified animal material in domestic samples were considered within the context of the second stage of the trial as summarized in Table 2. In stage 2, based on reporting from the laboratory combined with a review of pre sampling inspection reports, it was possible to determine that another 22 samples did not contain prohibited material on the basis that the establishments from which the samples were taken did not handle prohibited material.

For those domestic samples where review of the pre sampling inspection reports alone could not rule out the potential for prohibited material to be among the animal materials detected, i.e., where the facility handled both prohibited animal material and made feed for ruminants, an additional onsite inspection was conducted by CFIA. Based on the follow-up inspections, it was determined that another 16 samples did not contain prohibited material on the basis that all appropriate control procedures were being strictly adhered to in the establishments from which these samples were taken.

For the other 11 domestic samples, the CFIA could not rule out the possibility that some (likely an incidental level of) prohibited material may have been among the animal tissues detected in the laboratory. For 7 of these, the establishments enhanced their record keeping, flushing and/or sequencing practices, all of which have been verified by CFIA inspectors. With respect to the other 4 samples, the single establishment from which they were taken has ceased operation and no further action is required.

Table 2: Stage Two - Domestic Sample Results

For samples of feeds imported from other countries for which a result of detected was reported, there was no direct means within the context of this trial of conducting pre-sampling or follow-up inspections at the foreign establishment where the imported feed or ingredient originated. Importers were advised of the findings and asked to contact their suppliers for additional information. Any further analysis of the additional information provided will be considered outside the context of this trial. A summary of these results is contained in Table 3.

Table 3: Stage Two - Imported Sample Results

CONCLUSION

The results of the trial illustrate that the limitations for CFIA of this laboratory technique outweigh its potential utility. For example, microscopy is not capable of differentiating between animal tissues that can enter the feed chain through the grain harvesting and feed distribution system (e.g., incorporation of field mice or small mammals) from those that would be of concern in managing animal health risks for BSE within the scope of Canada’s feed control measures. In the end, it was necessary to rely upon physical inspection of facilities and records, as is routinely done within the scope of the Agency’s ongoing inspection program.

At this time, microscopy as a tool for evaluating compliance would only be seen as useful if undertaken in conjunction with existing inspection programs and with full recognition of its potential limitations.

¹All samples from same establishment.
²Imported Samples were from the United States and France.

Canadian Food Inspection Agency
February 2, 2005