Volume VIII Number 3 May/June 2000

Protecting Cattle from Liver
Abscesses Pays Dividends

Preconditioning the cattle you send to the feedyard pays dividends by improving gains and protecting animals from disease. But have you considered protecting your cattle from another disease that also impacts profits? Liver abscesses. You may not be aware of the problems associated with this condition, but a vaccine is available to help protect your investment.

Liver abscesses result from a disease complex known as acidosis-rumenitis-liver abscess complex. Fusobacterium necro- phorum, a normal inhabitant of the rumen, is the primary causative agent. Feeding a high-concentrate diet causes ruminal acidosis that impairs the integrity of the rumen wall, permitting opportunistic bacteria such as F. necrophorum to colonize, cause infection and then enter the liver.

That cause-and-effect relationship creates an interesting paradigm, considering that the very nature of cattle feeding is to put as much weight on an animal in the least amount of time possible. High-concentrate feed rations also impact the severity and incidence of liver abscesses. As energy levels of rations increase, problems associated with acidosis increase. Also, fermentable carbohydrates increase the acidosis risk.

Not Just A Feedyard Concern

Just placing your cattle in the feedyard without knowing about this risk can hurt you when it comes to selling cattle. If your cattle have a high incidence of liver abscesses, the packer will take notice. And if you're selling on a grade-and-yield basis, that notice will take the form of lower yield grades. The reason is that infected livers must be condemned for human consumption, with an estimated economic loss of up to $5 or $6 per affected carcass. But other losses occur at the packer level.

"The packer doesn't make any money on abscessed liver and offal products," says Larry Thomas, shift manager at Monfort in Grand Island, Neb. "Once the liver is ab-scessed, you lose the heart, lungs and paunch. So you're not making any money on those. Plus the stoppage of the line has an astronomical cost per minute. You may even have to saw the brisket off and trim and peel the inside skirt out, so the yield can't be that good."

Research also shows that severe liver abscesses negatively impact feedyard production efficiency by lowering slaughter weight and reducing feed efficiency. One research report states that liver abscesses decrease average daily gain as much as 11 percent and decrease feed efficiency as much as 9.7 percent. With those types of losses, controlling and preventing liver abscesses makes economic sense.

"The economic benefit of liver abscess control in feedyards has been proven by numerous researchers," says consulting veterinarian Don Cain, D.V.M., M.S., Broken Bow, Neb. "If it is true on a large scale like that, then it is more important for the person who retains ownership. That's because you're dealing with one pen. You need to maximize the profit per calf."

Control the Problem

There are steps to take to limit potential losses associated with liver abscesses. First, check that the feedyard you are dealing with understands the impact proper bunk and nutritional management has in limiting liver abscesses. Cattle susceptible to liver abscesses usually are in an environment with a lot of competition for bunk space.

But even the best nutrition and bunk space management may not prevent the problem. Feeding antimicrobials has been one method to reduce liver abscess incidences, however, the regular feeding of low-level antibiotics is meeting increased public scrutiny. Therefore, other alternatives must be examined.

"Control of any infectious disease using technology that minimizes antimicrobial use is attractive given the current regulatory environment," says Kelly Lechtenberg, D.V.M., with Midwest Veterinary Services, Oakland, Neb. "We are under continued pressure to minimize antimicrobial usage."

That technology now takes the form of an efficacious vaccine that limits the occurrence of liver abscesses. Recently, USDA approved Fusogard(TM), manufactured by ImmTech, for liver abscess control.

"Our trial data shows it reduces or eliminates the incidence of liver abscess," says Dr. Cain. "The economic data to date shows that we see anywhere from 3 to 7 percent improvement in cost of gain. As far as return on investment, I feel this product can give around a 5-to-1 return on investment."

Positive results

In the efficacy trials, ranch-origin cattle were placed in commingled pens of vaccinated and unvaccinated animals. All animals were fed tylosin (Tylan(R)) at the highest label rate during the trial. The study incorporated about 1,700 head of cattle in 13 separate trials. The cattle were on relatively consistent feedlot diets varying between 105 days on feed up to 188 days on feed.

Two 2-mL doses of Fusogard bacterin were administered in one of two protocols. In the first protocol, one 2-mL dose of Fusogard was given at preconditioning in the fall with the second 2-mL dose given upon arrival at the feedlot. In the second protocol, one 2-mL dose of Fusogard was given to cattle on arrival at the feedyard with the second 2-mL dose administered at reimplant time.

Both vaccinated and unvaccinated animals were slaughtered on the same day using six different packing plants to provide variation in scoring and handling.

Livers were rated: A-: 1-2 small abscesses or abscess scars present. A: 2-4 well-organized abscesses present, generally under 1 inch in diameter.
The photo above shows a healthy liver. Compare it to the photo below of an infected liver. It was classified as A+, meaning it had one or more large active abscesses present along with inflammation of the liver tissue surrounding the abscess.
A+: 1 or more large active abscesses present along with inflammation of liver tissue surrounding the abscess.

The results showed a significant liver abscess reduction in all trials. Overall average liver abscess reduction was 31.5 percent. A+ liver abscesses were reduced by 61.3 percent. Fusogard was equally effective when given at preconditioning and feedlot arrival compared to being given at feedlot arrival then reimplant time.

Not every trial was conducted on pens with high liver abscess incidences. In one trial, the controls had 7 percent total liver abscesses and the vaccinates had half that. "That's probably the key. Even under what people would assume is a low liver abscess incidence, the product still works and pays for itself," says Dr. Cain.

Ensuring Protection

"The best way to ensure your cattle get Fusogard is to make sure they arrive at the yard with the first dose in them," notes Dr. Cain. "That way, you've indicated to the feedyard owner what your desires are. Then all the feedyard owner has to do is give a booster on arrival."

One way to save even more money on processing costs once your animals enter the feedyard is to give all your vaccines and boosters at the ranch along with the ear tags and implants. However, this may not be advisable if your working pens are less than ideal.

"Beef quality is an issue, and this product is very tissue friendly with no injection-site problems," Dr. Cain adds. "Fusogard is a value-added biological. It gives you a beef product with less contamination and a healthier carcass for the consumer."

For more information about liver abscesses or Fusogard(TM), contact your veterinarian or ImmTech at 1-888-466-8325.

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