"We wanted to test how well these products work to control E. coli O157:H7 in a commercial feedlot with a large population of cattle that were fed in the summer and may be expected to have a high level of E. coli O157:H7," Renter said.

Using a commercial feedlot setting, the researchers studied more than 17,000 cattle during an 85-day period. They studied two products: a vaccine and a low-dose direct-fed microbial.

"What's unique about this study is the number of animals we used, the research setting and that we used commercial products in the way that any cattle producer could use them," Renter said. "We didn't want it to be any different than the way somebody would use the products in a commercial feedlot."

The researchers found that the vaccine reduced the number of cattle that were shedding E. coli O157:H7 in feces by more than 50 percent. E. coli shedding was reduced by more than 75 percent among cattle that were high shedders of E. coli.

While the vaccine label suggests that it is given in three doses, the researchers found that two doses of the vaccine significantly reduced E. coli.

The researchers also discovered that the low-dose direct-fed microbial product did not work as well as the vaccine. Renter said while the study used a lower dose of the direct-fed microbial and could find no evidence that it reduced E. coli shredding, it is possible that the direct-fed microbial product is more effective at a higher dose.

"This vaccine is an option for reducing E. coli," Renter said. "We have shown that this vaccine works and that it is a tool that could be adopted in the industry." 

—From ScienceDaily