December 14, 2010
by Joel Crews
Food-safety officials in the beef industry have good reason to be feeling optimistic based on initial results of Cargill’s research on the effects of a vaccine administered to a large sample of cattle at the feedlot level this past summer. The cattle, which were ultimately slaughtered at the company’s Fort Morgan, Colo., plant, showed positive immune-system response and had no adverse reaction to the vaccination, which was cause for announcing a second trial, planned for 2011, using feedlots and processing facilities in the Midwest.
This past month, Dan Schaefer traveled to Minneapolis to share the results of this research project, which has gotten the attention of a lot of people in the beef industry. At a presentation before the US Animal Health Association’s food and feed safety committee, Schaefer, Cargill’s assistant vice president for beef research and development, outlined the initial findings from the monthslong, $1 million research trial involving 85,000 cattle to determine the effectiveness of a vaccination used to prevent E. coli
“This was the first time we had talked about the results of the study,” Schaefer says. “We were able to get the antibody response we hoped for and we showed a directional difference in fecal prevalence and low prevalence in the trim [of the product from the control group and the treated animals].”
The bovine vaccination was developed by Willmar, Minn.-based Epitopix, which first developed its SRP technology to treat poultry in the 1990s. The patented technology was later adapted for the bovine industry to help control Salmonella
Newport in dairy cattle, which is now available commercially and widely used.
In March of 2009 Epitopix received conditional license from the US Dept. of Agriculture for its latest bovine vaccine designed to target E. coli
O157:H7. Based on earlier field tests, the vaccine eliminated 99 percent of the pathogen among cattle testing positive for E. coli
. It reduced the overall number of cattle testing positive by 85 percent, which piqued the interest of officials at Cargill.
“We were in contact with them a few times after that even though we weren’t sure when the product was going to come to market,” Schaefer says.
“Our new E. coli
O157 Bacterial Extract is the first O157 vaccine licensed for sale in the United States,” said Jim Sandstrom, general manager of Epitopix within days of the approval.
Once available commercially, Cargill rolled out its plans to implement a large-scale trial of the vaccine. Of approximately 85,000 cattle used in the trial, 60,000 received two vaccinations, with the remaining group receiving a single dose. Cargill assembled a test herd and a control-group herd by October of 2009. Vaccinations on the livestock began in November, 2009 and the slaughtering of the herd occurred in August 2010.
Kansas State Univ. graduate students and researchers led by Dan Thomson, professor and director of KSU’s Beef Cattle Institute, were directly involved both with the vaccine approval and then with Cargill’s trial.
Other academics were involved with the trial, including Texas Tech Univ.’s Guy Loneragan, an epidemiologist and professor of food safety and public health, who assisted in the test protocol design and in analyzing the data and publication of the findings. Additionally, officials with the US Meat Animal Research Center, Clay Center, Neb., were involved in taking hide samples as part of data collection to determine whether or not the vaccine has efficacy on non-O157 pathogens. Conclusions drawn from these cultures and samples are expected to be released in January 2011.
“This is a big decision for the industry and it’s a big move,” Schaefer says, “and it will require more than one research trial for us to be convinced.” Questions remain, he says about the completeness of the efficacy and whether vaccination of cattle in feedlots in the same proximity and whether the immunity overcomes that environmental challenge.
The first trial involved 10 feedlots, where all the livestock were vaccinated at least once. Every animal that was slaughtered and part of the “treated” group was vaccinated twice. A separate, “control” group was made up of cattle from other feedlots that were not vaccinated, but slaughtered in a similar time frame as those that were treated. “That allowed us to track all the way down to the beef-trimmings level and look at what kind of response we had at that level,” Schaefer says. The results at the processing-plant level were somewhat of a good-news, bad-news scenario. Thanks to numerous onfarm pre-harvest and post-harvest interventions developed and utilized for years by Cargill and the industry as a whole, the rates for the prevalence of E. coli
at the Ft. Morgan, Colo., facility were extremely low over the summer, and that included meat from the vaccinated and non-vaccinated cattle, according to Schaefer. Low pathogen prevalence is always good, he points out, but in this case, “it wasn’t the right timing for a trial” because the prevalence of the pathogen was so low in both groups that it wasn’t meaningful from a research standpoint. The test was designed to be able to detect a half-percent of difference between E. coli levels of the treated group and those of the control group. More than 3,000 ground beef trim lots of treated product and 10,000 lots of product from the control group were used for this part of the trial.
“There were thousands and thousands of pounds of beef trimmings and between both groups, the prevalence level was well below what we could detect,” Schaefer says, “so it became meaningless.”
For the next trial, the test and protocol will be similar to the first in terms of scheduling it to occur while cattle are at the feedlots during the summer months, when E. coli occurs most often. But the randomness of the pathogen creates challenges and researchers never know what they might get. “If it had consistent patterns, science would figure it out and we’d eliminate it pretty quickly,” Schaefer points out. “It’s a misconception that there’s a lot of O157. Industry has a very low prevalence, but when it happens it gets a lot of publicity.”
A significant bright spot of the initial study was the absence of any adverse animal effects, including injection-site lesions, loss of appetite, productivity losses or mortality of animals among the treated animals. “That may seem small, but that’s a huge concern for producers,” he says.
“It is exciting for Epitopix that we may now deliver the first immunological control tool to a very determined beef production industry,” Sandstrom said in a statement announcing the vaccination’s approval.
Should the second trial results, expected to become available in late 2011, convince more processors to adopt the practice, incorporating additional vaccinations to the feedlot routine shouldn’t be too invasive. Typical feedlots handle each animal at two different points “through the shoot,” when vaccines could be administered, Schaefer says. “They will handle them once at receiving,” when they are given other vaccinations, Schaefer says, and they will be handled again when they are about 90 days from slaughter, when the second dose can be administered. At Cargill’s feedlots, two doses is the preferred regimen to avoid potential complications relating to animal welfare and productivity issues.
Other companies are experimenting with a single-dose regimen, which likely involve heavier-weight yearling steers that spend less time on feed, have heavy placement weights and make only one trip through the shoot.
Schaefer points out that the success Epitopix has had with its Salmonella
vaccine, which is widely used in the dairy industry, bodes well for this newest vaccination and food safety improvements. Dairy cattle treated with the Salmonella
vaccination have shown increases in milk production, for example.“While it helps with productivity, it also helps those cull cows produce safer meat into the food supply,” he adds.
“The return on investment here is really a return for consumers. They expect safe food from us. I don’t know how to put a price on safe food.”