Liver abscess microbiota of feedlot steers finished in natural and traditional management programs.

As feedlot cattle consume grain, the rumen becomes more acidic. If the lining of the digestive tract is damaged, bacteria that normally remain in the digestive tract can enter the body. Certain bacteria like Fusobacterium necrophorum are involved in the formation of liver abscesses. Feedlot cattle are commonly fed an antibiotic (tylosin phosphate) to reduce the occurrence of liver abscesses, but increasing scrutiny is placed on the antibiotic use. However, the effect of eliminating the antibiotic used to prevent liver abscesses on the bacterial communities involved in liver abscess formation is unknown. This study compared the bacteria found within liver abscesses of cattle fed tylosin phosphate with that of cattle not fed tylosin phosphate. All liver abscesses contained F. necrophorum, and Bacteroides was the second most commonly identified bacterium. Trace amounts of bacteria known to colonize the mouth and digestive tract were observed. Trueperella, a bacteria targeted by tylosin phosphate, was found more frequently in liver abscesses from cattle that received no antibiotic. While the core bacterial composition of the liver abscess was unaffected by antibiotic supplementation to feedlot steers, reduced Trueperella in liver abscesses from cattle-fed tylosin phosphate could be related to a reduction in liver abscess prevalence.