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Parasite control research offers management options for beef producers

Researchers have uncovered management techniques that could have potential to control and reduce and Cryptosporidium spp. populations, decreasing the potential for environmental contamination and human infection.

Both Giardia and Cryptosporidium affect a variety of mammals - including horses, dogs, cattle and even humans. However, recent research funded in part by the Canada Alberta Beef Industry Development Fund (CABIDF) was specifically focused on finding ways to deal with infection in beef cattle.

"This research led us to a number of conclusions about how Giardia and Cryptosporidium parasites spread in cattle and what producers can do to keep their cattle - and the environment - healthy," says project leader Dr. Tim McAllister, researcher at Agriculture and Agri-Food Canada's Lethbridge Research Centre. "We believe reducing infection rates in cattle will help reduce outbreaks in humans."

Previous research has shown that Giardia and Cryptosporidium are significant parasites of cattle. McAllister and team members Dr. Merle Olson from the University of Calgary and Brenda Ralston with Alberta Agriculture, Food and Rural Development were interested in finding out more about infection levels and impact, and what producers can do to lower the infection rates.

"While research on these two parasites is far from complete, we now have some options that will help producers reduce infection rates in their herds and that's good news for the cattle industry and society as a whole," says McAllister.

Giardia and Cryptosporidium spp. are two of the most common protozoan parasites that infect mammals worldwide. Giardia can infect cattle and humans when cysts are shed by cattle and are ingested through the fecal-oral route or through the consumption of contaminated water. In some cases, infection in cattle can cause diarrhea, decreased weight gain and impaired feed efficiency.

Cryptosporidium spp. also infect hosts through the fecal-oral route or through the consumption of oocysts, shed by cattle, in contaminated water. In otherwise healthy cattle, it is often self-limiting but, it can be chronic in immuno-suppressed animals. Occasionally, Cryptosporidium has been associated with severe outbreaks in calves with mortalities as high as 30 percent.

These parasites have been associated with human health and environmental concerns, and many of those concerns stem from how the parasites might be transferred from cattle to humans.

Objectives of the research were to determine if Giardia and Cryptosporidium cause significant costs to the cattle industry, and to find management methods that could mitigate the occurrence of both parasites and the transfer between cattle. Researchers also investigated the use of antibiotics in cattle fed on pasture and the survivability of both parasites in composted manure.

"We found that a confined environment increases the transfer of both parasites, so giving cattle more room to roam will help reduce transfer rates and infection levels," McAllister adds. "We also found that fenbendazole (Safeguard) can be used on pasture to control Giardia infection."

Regarding manure management, composting can be used to kill both parasites. This is significant, says Olson, because removing the parasite from manure through composting will lead to a reduced likelihood that the parasite will contaminate ground or surface water sources.

"Further to our composting suggestion, cow/calf producers must be diligent regarding hygiene practices when calving," says Ralston. "We suggest calving be done on open pasture, and as much as possible, restrict calf access to open water. With Cryptosporidium, infection is self-limiting and animals stop shedding oocysts after 40 days, which makes those first 40 days critical in limiting transfer of the parasite. Giardia is a little trickier, because full-grown cows can continue to shed cysts."

The CABIDF-funded research approached the parasites more as environmental or human health concerns, so it did little to indicate how much of a performance problem these parasites are for producers. However, McAllister says that's one of the many areas that needs continued research.

CABIDF is a joint $16.4 million fund of Alberta Agriculture, Food and Rural Development and Agriculture and Agri-Food Canada. The Fund is administered by Alberta Beef Producers and has supported more than 50 projects in six major categories identified to benefit the Alberta beef industry.

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