Challenging economic times are forcing producers across the cattle industry to pay attention to efficiency. Recent studies have shown that ...
Challenging economic times are forcing producers across the cattle industry to pay attention to efficiency. Recent studies have shown that there are few better ways to do that than by taking control of your parasite problem, particularly by recognizing the impact of liver flukes.
The National Beef Quality Audit has rated liver flukes one of the top ten quality issues in the beef industry. The common liver fluke, Fasciola hepatica, is now endemic to 26 states. Traditionally these flukes have been found in the Gulf and PacificCoast states, but as cattle and hay have increasingly been moved across state lines, liver flukes have spread. They are now found from Montana to Nebraska, Oregon to Oklahoma to Nevada.
Dr. James Hawkins, DVM and parasitology consultant for Merial, warns producers in areas where flukes have not traditionally been a problem to watch out for unexplained growth or reproduction problems.
“Producers may not see the affect of flukes right away, or they can have a few quiet seasons when they don’t worry as much until a necropsy is done and liver damage is obvious,” says Dr. Hawkins. “And in those areas where flukes are not traditionally found, they aren’t on the radar screen. Sometimes even veterinarians are guilty of not looking for flukes because they haven’t dealt with them before, or because they aren’t real sure what they are looking for in fecal or liver samples.”
The pain liver flukes cause is often felt in your wallet before the effects are obvious in your herd. Liver damage hurts reproductively, decreases fertility, weight gain, feed efficiency, and the immune system so that animals can’t handle illness or medications and vaccines as well. And a liver that is full of liver flukes is likely to be condemned, impacting your bottom line.
Dr. Hawkins related an experience with a Montana rancher who didn’t know he had a liver fluke problem until he got news from the slaughterhouse that his livers were 100 percent condemned.
“His reproduction rate was still good and his animals still looked good,” Dr. Hawkins says, “but that could have turned around really quickly.”
Fortunately, a well-planned treatment program can mitigate liver fluke damage and prevent future problems. While there is no way to heal liver damage, drugs can prevent additional damage in adult animals and parasite infection in young and future animals.
A 2007 study by researchers at IowaStateUniversity found that conducting a parasite control program is the most economically important practice in beef production. The researchers compared 170 previous studies examining parasite control programs and evaluated the technologies available to beef producers. Cow/calf producers that used parasite control had a 23 percent advantage in weaning rate and four percent in weaning weight compared to those producers who did not.
Stocker and feedyard producers were similarly impacted by parasite control, or lack thereof. For stockers, the average daily gain is nearly 18 percent higher for those who use parasite control, an increase in breakeven price of $20.77 per head. Feedyard control is also critical. Feedyards that do not use parasite control had an increased per head production cost of $22.16.
Producers can efficiently and effectively attack the liver fluke problem on two fronts: through drug treatment and pasture/herd management. Understanding the liver fluke’s life cycle, the needs of your herd and your business, and the capabilities of the drug treatments will all aid liver fluke management.
A closer look at this nasty parasite
The liver fluke’s life cycle is dependent upon two host animals, the ruminant and the freshwater snail. Adult liver flukes live in the host ruminant’s liver bile duct, laying eggs that are then carried out with the animal’s manure and deposited in pastures. When the eggs hatch, the juvenile larva, called miracidium, migrates to find a freshwater snail host. If there is no snail to be found, the larva will die. When a snail is found, the larva will penetrate the snail and begin reproducing asexually, multiplying as many as 600 times.
After a five to seven week development, tadpole-like liver flukes, called cercariae, leave the snail to attach to surrounding vegetation. The cercaria then secretes a protective covering, metacercaria, and begins waiting for a ruminant to come along. Perched on the edge of a blade of grass or attached to a bit of soil in a pond, the fluke will be ingested by a grazing ruminant, and will enter the stomach. It will then migrate to the intestine, where it leaves the protective cyst and burrows into the intestinal wall. The fluke continues its journey to the abdominal cavity, through the liver, and eventually to the bile duct, where as an adult, the fluke lays eggs and the cycle begins again. The entire process can take anywhere from 16 weeks to 24 weeks.
Extreme temperatures will kill liver flukes, but theoretically, any part of the country where freshwater snails can survive, the liver fluke can too. In places like Montana, heavy rain or abnormally temperate weather might create perfect conditions for the fluke, while in others, like Florida, these conditions are the norm. In both instances, producers should be on the lookout for low, moist areas where snails are likely to reside and cattle are likely to become infected, because if you find one animal that is carrying flukes, it is likely that the whole herd is carrying them.
If damaging growth, gain, and reproduction weren’t enough, liver flukes can also cause death. While it is relatively rare for liver flukes alone to cause death, the damage they cause to the liver can cause secondary infections that lead to death. This is often the case when liver flukes and Bacillary Hemoglobinuria, commonly known as Redwater, get together. Redwater is a bacterium commonly found in western states like California. It resides in the liver and, by itself, typically doesn’t cause damage to the animal. However, when liver flukes are present, the bacteria are activated and can cause death in less than 24 hours.
Fortunately, there are three primary options for treatment of liver flukes and prevention of liver fluke damage, IvomecÒPlus, CuratremÒ, and ValbazenÒ. IvomecÒPlus is an injectable combination of ivermectin and clorsulon that treats adult liver flukes, internal parasites like tapeworms and stomach worms, and external parasites like grubs and sucking lice. CuratremÒ is an oral drench containing only clorsulon, treating immature and adult liver flukes. ValbazenÒ is an oral treatment containing albendazole that kills adult liver flukes and internal parasites.
At the Adams Ranch in Fort Pierce, FL, Alto “Bud” Adams and his family have been dealing with liver flukes for the last 50 years with success. The Adams Ranch is the 15th largest cow-calf operation in the country and 1997 recipient of the National Cattlemen’s Beef Association’s Ranch of the Century award. The family runs 10,000 head of Braford cows, producing feeder steers, replacement heifers, and breeding bulls. A combination of management and treatment practices have allowed the Adams family to keep their herd as healthy and profitable as possible.
Mike Adams, son of Bud, advises producers to consider how treatments will best suit their herd and management practice.
“To some degree, producers can adapt a treatment schedule to when they work their cattle or the type of herd they have,” says Adams. “For example one producer might use a pour-on because they have a smaller herd, whereas somebody with a larger herd might use an injectable treatment.”
At the Adams’ ranch, brood cattle are treated annually with CuratremÒ, while heifers are treated at weaning with CuratremÒ and again with IvomecÒPlus before being shipped. They treat animals during the late winter and spring, between January and March, while doing branding.
In general, experts recommend treatment twice a year during the spring and late fall/early winter. Dr. John Maas, DVM at the University of California at Davis and a Cooperative Extension Specialist, advises producers to first work with their veterinarian to determine if flukes are a problem by conducting a fecal analysis, blood enzyme test, and using the veterinarian’s general knowledge. Second, producers should design a strategic deworming program that includes which drugs will be used and how frequently treatments will be administered. Finally, producers should consider how to best manage pastures to avoid contact with flukes or fluke breeding grounds if at all possible. One way to accomplish that is by using wet areas sparingly because of their snail population.
Treating for liver flukes takes time and planning, but protecting your herd will also protect your investment, and your return, which in these trying economic times is always welcome.
