Investigations into Canada’s 14th and 15th cases of BSEinfected cattle turned up no evidence that the country’s cattle herd and beef consumers are at any greater risk.
The Canadian Food Inspection Agency on April 16 released its reports on the two cases, both born well after Canada first imposed a ban on feeding ruminant tissues to ruminants in 1997.
Case 14, a Gelbvieh-cross commercial beef cow found in northern Alberta last July, was born March 20, 2002 and was over six years old when it died. BSE was confirmed in the cow in August.
Out of 106 animals traced in the CFIA’s investigation from the birth and feed cohorts of Case 14, 80 were confirmed dead or slaughtered, 14 were presumed dead or slaughtered, nine live animals were found on two farms and destroyed, and three others were ruled “untraceable” due to limited records.
The calf, creep feed and starter rations made available to Case 14 came from two different feed millers, neither of which had production records dating back to the CFIA’s “period of interest.”
But because Case 14 was born after 1997, CFIA felt it “very unlikely that ruminant meat and bone meal was intentionally used” in any of the three rations or the loose mineral salt that was processed at one of the two feed plants.
“However, as production records are not available for review, it is not possible to rule out that contamination during production could have taken place,” the agency wrote.
One of the two feed mills handled ruminant meat and bone meal (MBM) but had procedures in place to keep it out of ruminant feed, CFIA said. The other mill didn’t handle ruminant MBM but did use a premix from another plant that did handle such ingredients.
The other case was Canada’s most recent: a registered Holstein dairy cow, born Jan. 1, 2001 and confirmed as BSE positive by Nov. 14 last year. Neither case entered the food or feed supply, CFIA said.
Case 15 had spent its entire life on the same Fraser Valley dairy farm in British Columbia, CFIA said. Out of 187 animals traced from Case 15’s feed cohort, 122 were confirmed dead or slaughtered; 24 presumed dead or slaughtered; five confirmed as exported for slaughter, with the importing country since notified; 14 deemed “untraceable” due to limited records; and 22 live animals traced, quarantined and now scheduled to be destroyed.
“Considering the farm’s feeding regime and specific production records reviewed, a likely source of exposure to BSE infectivity appears to be potentially contaminated heifer ration,” CFIA said.
But potential contamination of a lactation ration, which was mixed using the same on-farm mixer wagon as for the dry cow rations, can’t be ruled out, CFIA said. Nor can the potential contamination of two different types of mineral blocks, which both came from a facility that handled ruminant MBM.
Again, CFIA said, the “period of interest” comes well after the start of the 1997 feed ban, making it “unlikely” that MBM was intentionally used in the mineral blocks. But again, with production records unavailable, contamination during manufacturing can’t be ruled right out, the agency added.
In either case, CFIA said, the detection of BSE “does not change any of Canada’s BSE risk parameters. The location and age of the animal are consistent with previous cases. Surveillance results to date, including this case, reflect an extremely low level of BSE in Canada.”
Public health measures put in place in 2003 assure the safety of beef produced in Canada, as all specified risk materials (SRMs, the tissues known to harbour the misfolded proteins causing BSE in infected animals) are removed from animals slaughtered for food.
As well, CFIA noted, the 1997 feed ban is “effectively preventing the amplification of BSE in Canada’s feed system” and was boosted in 2007 to keep SRMs out of all food, feed and fertilizer, thus “preventing more than 99 per cent of potential BSE infectivity from entering the Canadian feed system.”