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Evaluation of the Ability of Seaweed Extract (Tasco-14) to Reduce the Duration and Intensity of Fecal Shedding of Escherichia coli O157:H7 and Total E. coli by Cattle

McAllister, Tim
Agriculture and Agri-Food Canada
Start date
End date
A pre-harvest intervention strategy to reduce the duration and intensity of E. coli O157:H7 fecal shedding by cattle would prove to be instrumental in minimizing carcass contamination with E. coli O157:H7 and increasing the safety of Canadian beef. Acadian Seaplants Limited produce TascoTM, a proprietary product processed from the seaweed Ascophyllum nodosum. A. nosodum is the most widely researched seaweed for agricultural purposes and is found growing along the coastline between high and low tides of the North Atlantic Ocean extending from Nova Scotia to Norway. Seaweeds have been fed to livestock throughout history and have GRAS (Generally Recognized as Safe) status with the FDA. A recent study showed that supplementation of Tasco - EX (extract from A. nodosum) to feedlot cattle two weeks prior to slaughter reduced E. coli (especially E. coli O157:H7) levels in fecal and hide samples (Behrends et al, 2000). More recently these same effects have been observed by incorporating Tasco -14 at 2% of the ration (DM basis) for a period of 2 weeks immediately before slaughter (Barham et al., 2001; Evans, 2002).

The goal of this research is to evaluate the effects of Tasco-14 on the fecal shedding of E. coli O157:H7 by cattle through the use of controlled animal inoculation studies. A dietary intervention strategy, such as the incorporation of Tasco-14 into the diets of cattle two weeks prior to slaughter, would prove to be an economically feasible method to control E. coli O157:H7.

More information
Expected Impact of Project Outcomes on Food Safety in Ontario: Pro-active steps must be taken to reduce the fecal shedding of E. coli O157:H7 by livestock. To date, there are no effective methods to control the fecal shedding of E. coli O157:H7 by cattle. A recent study showed that incorporating Tasco-14 at 2% of the ration (DM basis) for a period of 2 weeks immediately before slaughter reduced levels of E. coli O157:H7 in the feces and on the hides of cattle (Barham et al., 2001; Evans, 2002). The present study is designed to evaluate the effectiveness of Tasco-14 in reducing the incidence of E. coli O157:H7 in experimentally inoculated cattle and may represent the identification of an economically feasible management strategy to control E. coli O157:H7 in cattle and thereby lower the associated risk of environmental contamination. Proactive approaches to controlling E. coli O157:H7 in beef cattle would represent a significant contribution towards minimizing the risk that this pathogen presently poses on the Canadian food supply.

For more information, please visit the Ontario Ministry of Agriculture, Food & Rural Affairs (OMAFRA) Food Safety Research Program.

Funding Source
Ontario Min. of Agriculture Food and Rural Affairs
Project number
Escherichia coli
Chemical Contaminants