July 22, 2010

US grass-fed beef shows unclear safety benefit

Study shows levels of bacteria in grass-fed and conventionally raised beef has little difference in samples of US retail beef products.

Despite marketing claims that grass-fed beef is safer, researchers of Foodborne Pathogens and Disease said they found no significant differences in total coliform bacteria, Escherichia coli, or Enterococcus species. They also looked at antimicrobial resistance and found mixed evidence, with some signs of increased resistance in bacteria isolated from conventional beef as compared with grass-fed beef.

"Taken together, these data indicate that there are no clear food safety advantages to grass-fed beef products over conventional beef products," according to investigators from Purdue University in Indiana and Zhejiang University in Hangzhou, China.

The investigators stated that grass-fed beef products are often marketed as safer than conventional grain-finished beef because of the potential effects of the grass diet on gut microbes. However, they suggest that other factors, including where and how beef is processed and whether cattle are fed preventive antimicrobials, may have larger effects on contamination in finished products. The authors say that grass-fed cattle are more likely to be processed in small facilities and are less likely to be given preventive antibiotics.