30 April 2013

2 minute read

E. coli O₁₅₇:H₇ inhabits the hindgut of cattle and is commonly shed in the feces. However, a high variability exists across cattle with some animals shedding large amounts of the bacteria and others very little.

Less than 5 per cent of animals shed at what scientists call 'high levels' (>10⁴ cfu/g) although the feeding of distiller's grains can increase fecal shedding of E. coli O₁₅₇:H₇ in cattle.

This study looked at the use of protein-based vaccines containing siderophore receptors and porin (SRP®) and/or a direct-fed microbial (DFM) against fecal shedding of E. coli O₁₅₇:H_7.

Pens of commercial feedlot cattle fed a corn-based diet with around 25 per cent DG (dry matter basis) were tested during the summer. The O₁₅₇:H₇ SRP® vaccine inhibits iron uptake by the bacteria while Bovamine® direct-fed microbial has probiotic effects. Both are commercially available in the United States.

The study design included two pen-level measures of fecal shedding: overall fecal prevalence of O₁₅₇:H₇ and the prevalence of high-shedding animals. Of all treatment protocols, only the two?dose SRP® significantly reduced overall fecal prevalence and the percentage of high shedders, with no significant interactions between treatment and time of sampling.

The administration of the DFM had no significant effect on the prevalence of fecal O₁₅₇:H₇ or the prevalence of high shedders. With > 50 per cent reduction of E. coli O₁₅₇:H₇ shedding and > 75 per cent reduction in high shedders, this two-dose regimen of the E. coli SRP® vaccine appears to be an efficacious pre-harvest intervention in a commercial feedlot setting.

April 2013