– Steve Boyles, OSU Beef Extension Specialist
Liver abscesses are the primary cause of liver condemnation in feedlot cattle. Two scientist ( C. D. Reinhardt and M. E. Hubbert) reviewed the research on the topic. Severe abscesses may reduce the value of beef carcasses by $38 per animal. Cattle slaughtered in the Midwest states average 13% with and 4% being severe liver abscesses.
There has been an increase in prevalence of liver abscesses in Holstein steers, rising from 12% in 2003 to 55% in 2013. Prevalence of liver abscesses in Holsteins fed in places like Ohio may average 23% with 9% being severe. One reason liver abscesses are higher is that Holsteins are typically on feed longer than typical beef breed cattle.
Causative Factors
High grain diets can increase the acid level in the digestive tract and this can erode the rumen wall. Certain bacteria then get into the blood stream and get lodged in the liver and cause infection.
Unlike cattle, intensively fed sheep, even when fed high-grain, low-roughage diets, rarely experience rumenitis or liver abscesses. However when sheep are fed some cattle hair they have an increase in prevalence of rumenitis, suggesting that grooming behavior of feedlot cattle, licking themselves or others, results in some of the damage and perforation of the rumen wall.
Antimicrobials
The most common method of controlling liver abscesses in finishing cattle in the United States is continuous feeding of antimicrobial compounds; the most commonly used antimicrobial for this purpose is tylosin phosphate. However, even when tylosin is fed, liver abscesses commonly occur in 12 to 18% of feedlot cattle.
Roughage Level and Form
Drs. Loerch and Fluharty at OARDC reported that increasing the amount of corn silage from 0 to 15% reduced the percentage of condemned livers from 29 to 15%. They also found that elevating the roughage level late in the finishing period reduces liver abscesses
Although roughage level provided during growing and finishing appears to influence incidence of liver abscesses, form of the roughage provided also appears to influence prevalence. The roughage needs to be sufficiently coarse to provide a true roughage or scratch factor within the rumen. Roughage causes the animal to create more saliva. More saliva increases the acid-buffering capacity in the rumen. Vaccination against the bacteria that causes liver abscesses has shown little benefit in field.
Because roughage is costly and difficult to manage in the feedyard future studies should focus on means to maximize the benefits of roughage by altering the timing, level, and form of roughage included in finishing diets.