Research says liver abscesses may cost beef industry $250 million

Liver abscesses affect the quality and profitability of cattle by millions of dollars in North America.

A Canadian beef quality audit done 10 years ago estimated an annual cost of liver abscesses to be $61 million.

However, that does not include “unseen” costs, such as reduced growth efficiency, increased feed costs and added carcass trim. If using more recent U.S. research, the number can be closer to $250 million.

“The important thing was that most of the losses that were associated with that number were before slaughter,” Dr. Rob Gruninger of Agriculture Canada told a recent Alberta Beef Producers Beef Research Showcase.

“So these are your increased energy maintenance. A pen that has 20 per cent animals with liver abscesses will have four per cent increased maintenance energy cattle with A-plus liver.”

A-plus livers are defined by being severely abscessed with multiple small abscesses, as opposed to A-minus livers with one or two small abscesses and a carcass weight that is lower by approximately 29 pounds.

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Varied by individual, the resulting loss is $11 to $275 per animal.

Liver abcesses hard to diagnose

The difficulty with liver abscesses is that they cannot be diagnosed until the cattle are processed because they often do not show clinical signs unless they have been severely impaired.

Ultrasound has proven to be an ineffective way to capture the entire liver. The hope is that a blood-based test looking at gene expression will soon be developed.

Numbers thrown around in feedlots estimate 10 to 30 per cent of cattle have liver abscesses in North America, with Canada being on the higher end of the spectrum.

Steers are found to have more abscesses than heifers. The more days an animal is on feed, the higher the incidences of liver abscesses. The more digestible the diet, the more likely there will be gastrointestinal issues.

Dairy cattle have higher rates than beef cattle, popping up more in summer months than winter. Diets of wheat and barley tend to produce higher rates than corn andsorghum, according to Gruninger’s study data, along with silage over hay.

Current theory

“The currently accepted theory of how liver abscess is developed is that it’s related to acidosis, and so the consumption of highly fermentable diets results in the rapid production of volatile fatty acids. The rumen is only able to absorb those acids at a certain rate. So if you’re producing more acid than the animal is able to use for growth, then the pH of the rumen is going to decrease,” said Gruninger.

“If it decreases to enough of an extent for a long enough period of time, you can get damage to the rumen layer, which can allow for bacteria in the gut to get into the rumen layer and into the bloodstream (ruminitis). Once bacteria get into the bloodstream, they go through the liver, through the portal vein, where they have a potential to colonize and form an infection.”

Another hypothesis is that hind gut acidosis and epithelial damage (cecum/colon) may also allow bacteria to cross into the bloodstream to reach the liver.

“When there is acidosis in the rumen, you also get depressed rumen pH in the lower gut,” said Gruninger.

The core bacteria found most commonly in abscessed livers are fusobacterium and bacteroids. Given that both are found in healthy and abscessed livers (at higher levels), it is the triggering factors that have to be considered, be it type of diet, stress of the animal and days on feed.

The problem may be getting worse

Given that beef cattle have been pushed to greater finishing weights in recent years, with more days on feed, the thinking is that any numbers taken today would dwarf the economic impact from the studies conducted 10 years ago.

Producers in the audience during the question period hypothesized that the incidence of liver abscesses is probably five times larger than the numbers from 10 years ago.

“If there was a way to identify it earlier, better (feed) management decisions would be great. The closest thing I’ve seen in data related to that is the beef on dairy. Those animals are on feed for, say, an extra 100 days relative to an Angus cow, and you see significantly higher rates of abscesses,” said Gruninger.

Antibiotics may help, but will they be available?

Tylosin is the primary feed additive antibiotic used to battle liver abscesses in cattle by 30 to 35 per cent without affecting gain.

However, there is increasing pressure federally to reduce antimicrobial use in livestock.

Gruninger said alternatives should be sought in case Tylosin is eventually banned.

Current approaches, such as more fibre/forage, yeast products, direct-fed microbials, essential oils and a dated fusobacterium-specific vaccine, have shown inconsistent or inconclusive results.

Reducing chronic pen overcrowding, avoiding disruptions during diet transitions, choice of grains in feed and managing days on feed were all suggestions made by Gruninger in unison with Tylosin until a better alternative vaccine can be found.

“The goal of the research is, can we find some other (effective) ways?” said Gruninger.

“I think the most feasible would be, could we figure out how to make a vaccine that works well enough that is cost effective and makes sense to use? Maybe targeting more than just fusobacteria.”