"While we are pleased with the preliminary results, we are also eager to see completed analytical work currently underway by independent researchers at Kansas State and Texas Tech universities, the US Department of Agriculture Meat Animal Research Center and the Beef Check-off, which should be available early in 2011,” said Dan Schaefer, Cargill assistant vice president for beef research and development, while addressing the food- and feed-safety committee of the US Animal Health Association in Minneapolis on Nov. 14. “Because we saw a favorable immune-system response to the vaccine we were hoping for, and the cattle had no adverse reaction, we believe there is enough evidence to move forward with a second vaccine trial, and anticipate doing so in summer 2011, at a Midwest beef-processing facility supplied by midsize feedlots in the region.
“We're determining the best way to proceed with this science-based, evolutionary process, which we hope will lead to validating the potential value of vaccine as another food safety tool for beef production," he added.
Many factors influence the potential effectiveness of vaccine for reducing naturally, randomly occurring E. coli O157:H7 in beef cattle, including weather, geography, seasonality, animal and herd care and management, vaccine dosage and others, which creates a challenge in replicating the prior trial, Schaefer said.
Cargill also noted a low level of E. coli O157:H7 in the beef being produced at Fort Morgan from the non-vaccinated (control group) cattle during the time vaccinated cattle were being harvested, which could potentially influence the significance of the data currently being analyzed by independent researchers.
Researchers are trying to better understand the meaning and value of the reduction in E. coli O157:H7 in beef from the vaccinated animals, compared with beef from those that did not receive the vaccine. This vaccine trial was the first pre-harvest intervention trial completed that monitored activity from the time of vaccination through measurements in meat.
"The low level of E. coli O157:H7 in the beef from control cattle is something we need to take into consideration when we analyze the data to determine the vaccine's true impact and potential," Schaefer said. "The scientist in me tells me much more research remains to be conducted before we can draw any meaningful conclusions about the long-term efficacy of vaccine use to reduce any strain of bacteria potentially found in beef that could pose health risks to consumers."
The $1 million, 2010 trial involved the entire cattle supply from 10 feedlots being vaccinated and dedicated to Cargill for harvesting at Fort Morgan. Of the 85,000, nearly 60,000 head of cattle received two doses of the vaccine produced by Wilmar, Minn., based Epitopix LLC, one dose upon arrival at the feedlot and one dose approximately 90 days prior to harvesting. The remaining cattle received a single dose and served as buffers prior to and following those cycling through the feedlots that received two doses. By providing buffers, Cargill established the scientific controls required to test the effect of whole feedlot vaccination under commercial conditions.