January 12, 2009
Contact: Dr. Michael J. Baker, Cornell University, 607-255-5923; Cornell Cooperative Extension: Clinton County: 518-561-7450; Essex: 518-962-4810; Franklin: 518-483-7403; Jefferson: 315-788-8450; Lewis: 315-376-5270; St. Lawrence: 315-379-9192

NNYADP Research First to Identify Beef Cattle Parasite as Present in Region and Help Producers Develop Management Strategies

The presence of the large liver fluke has been confirmed in Northern New York. Project leaders Cornell University Beef Extension Specialist Dr. Michael J. Baker and veterinarian Dr. Laura B. Raymond positively identified the large liver fluke (Fascioloides magna, also known as the deer fluke) in beef livers at two of five slaughter plants in Northern New York.

In addition to identifying the large liver fluke in the cattle livers at the slaughter plants, Baker and Raymond are working with Northern New York beef producers on management strategies to cope with this parasite.

Baker says, “This project was developed to answer the question is the large liver fluke present in Northern New York. The answer is yes, particularly in wet pasture areas. Now we need to learn more about how the liver large fluke impacts cattle health. Currently, we can work with producers to develop pasture management plans to reduce exposure.”

White-tailed deer shed the eggs of the large liver fluke into warm, moist grasslands and pasture shared by livestock. The fluke’s eggs migrate into freshwater snails that serve as an intermediate host. The snails shed a tadpole-like form of the fluke into pastures where beef cattle and other
grazing animals ingest the parasite and become the dead-end host for the large liver fluke.

Dr. Raymond, a large animal veterinarian with the Watertown Animal Hospital, says, “Clinical signs of cattle infected with large liver flukes are difficult, if not impossible, to see. Diagnosis is currently only possible with post-mortem examination of the liver at the slaughter plants.”

The post-mortem presence of just one of the one-inch-wide, one-to-three-inch-long, reddish-brown, leech-like large liver flukes in a cattle liver is cause for condemnation of the liver, removing it from the food supply per U.S. Department of Agriculture regulations. The rest of the carcass can be processed as meat products.

Although the impact of the large liver fluke on beef cattle production is not yet documented, producers suspect the parasite of damaging reproductive efficiency, causing lower calf weights, and slowing heifer growth.

Northern New York Agricultural Development Program Beef Subcommittee member Ralph Chase says, “Because North Country beef producers are increasing the use of grasslands to improve production and profitability, the farmers of the Northern New York Agricultural Development Program Beef Committee identified this research project as a way to determine our level of risk and to develop practices for reducing beef herd losses to the large liver fluke.”

Dr. Baker says, “The challenges with the large liver fluke are that until now it has not been documented in this area of the U.S.; it can only be diagnosed post-mortem; and no good control measures exist compared to the small liver fluke (Fascioloides hepatica) which can be controlled with currently available anthelmentics (parasite-killing or expelling drugs).”

Raymond notes that a Michigan State University study is adding to the study of the large liver fluke in an area with parallels to Northern New York.

“Veterinarian Dr. Dan Grooms has written that while nearly 100 percent of the livers of the first calves raised from heifers purchased under the Michigan Beef Improvement Program study were condemned due to large liver fluke, more than 90 percent of the calves graded mid-choice or better for carcass quality. The calves were raised in the Upper Peninsula area of Michigan which is agriculturally similar to Northern New York,” Raymond says.

To help continue the monitoring of the presence of the large liver fluke in Northern New York beef herds, Dr. Baker suggests that producers talk with their meat processors about any damage seen in their cattle’s livers and to work with the processors to collect a sample of any flukes found for positive identification by the farm’s veterinarian.

Other species at risk of infection by the large liver fluke are dairy cattle, sheep, goats, elk, moose and camelids.

For assistance in dealing with liver fluke infections, contact your veterinarian or your local Cornell Cooperative Extension office. For more information on beef production in Northern New York, go online to the Northern New York Agricultural Development Program (NNYADP) website at www.nnyagdev.org

Collaborators on the NNYADP-funded large liver fluke research project included Cornell Cooperative Extension educators Brent Buchanan (St. Lawrence County), Anita Deming (Essex County), Ron Kuck (Jefferson County), and Michele Ledoux (Lewis County). #

More Info
Scientific names:
large liver fluke, or deer fluke: Fascioloides magna; common liver fluke:
Fasciola hepatica.

Estimating Losses to Small Liver Flukes – Although the small liver fluke can be controlled with drugs, a University of Florida study (Liver Fluke Control in Beef Cattle by M.B. Irsik, Charles Courtney III, and Ed Richey) reports that the Florida beef industry loses $10 million annually to small liver fluke (Fascioloides hepatica) infection. A 2000 National Beef Quality Audit by Colorado State University, Oklahoma State University and Texas A&M University, identified small liver fluke (Fascioloides hepatica) infestations among top 10 beef quality issues with 24.1% of U.S. cows & bulls infected with liver flukes at slaughter.