Forage Feeding to Reduce Preharvest Escherichia coli Populations in Cattle, a Review

• Published in: Journal of dairy science Vol. 86; no. 3; pp. 852 - 860
• Main Authors: Callaway, T.R., Elder, R.O., Keen, J.E., Anderson, R.C., Nisbet, D.J.
• Format: Journal Article
• Language: English
• Published: Savoy, IL Elsevier Inc 01.03.2003; Am Dairy Sci Assoc; American Dairy Science Association
• Subjects: Animal Feed; Animal productions; Animals; beef; beef cattle; Biological and medical sciences; cattle; Cattle - microbiology; cattle feeding; Colitis - microbiology; dairy cows; Diarrhea - microbiology; dietary carbohydrate; Disease Reservoirs; Edible Grain; enterovirulent Escherichia coli group; Escherichia coli; Escherichia coli Infections - prevention & control; Escherichia coli O157 - growth & development; Escherichia coli O157 - pathogenicity; Escherichia coli O157:H7; Feces - microbiology; feed grains; feeding; finishing; food pathogens; foodborne illness; forage; Fundamental and applied biological sciences. Psychology; hay; Hemorrhage - microbiology; human diseases; Humans; intestinal microorganisms; Meat - microbiology; milk; rumen fermentation; starch; Terrestrial animal productions; Vertebrates; EHEC; Escherichia coli; feeding; HUS; forage; cattle; IMS; Farming animal; Animal feeding; Dairy cattle; Ox; Cow; Review; Vertebrata; Mammalia; Bacteria; Artiodactyla; Biological contamination; Ungulata; Enterobacteriaceae; Feed
• ISSN: 0022-0302; 1525-3198
• DOI: 10.3168/jds.S0022-0302(03)73668-6

Although Escherichia coli are commensal organisms that reside within the host gut, some pathogenic strains of E. coli can cause hemorrhagic colitis in humans. The most notable enterohemorrhagic E. coli (EHEC) strain is O157:H7. Cattle are asymptomatic natural reservoirs of E. coli O157:H7, and it has been reported that as many as 30% of all cattle are carriers of this pathogen, and in some circumstances this can be as high as 80%. Feedlot and high-producing dairy cattle are fed large grain rations in order to increase feed efficiency. When cattle are fed large grain rations, some starch escapes ruminal microbial degradation and passes to the hindgut where it is fermented. EHEC are capable of fermenting sugars released from starch breakdown in the colon, and populations of E. coli have been shown to be higher in grain fed cattle, and this has been correlated with E. coli O157:H7 shedding in barley fed cattle. When cattle were abruptly switched from a high grain (corn) diet to a forage diet, generic E. coli populations declined 1000-fold within 5 d, and the ability of the fecal generic E. coli population to survive an acid shock similar to the human gastric stomach decreased. Other researchers have shown that a switch from grain to hay caused a smaller decrease in E. coli populations, but did not observe the same effect on gastric shock survivability. In a study that used cattle naturally infected with E. coli O157:H7, fewer cattle shed E. coli O157:H7 when switched from a feedlot ration to a forage-based diet compared with cattle continuously fed a feedlot ration. Results indicate that switching cattle from grain to forage could potentially reduce EHEC populations in cattle prior to slaughter; however the economic impact of this needs to be examined.