The Problem With Parasites
As you turn your beef cattle out to graze this spring, controlling parasites to head off pasture buildup can mean the difference between being in the red or being in the black.
While producers want to protect their herds' health and performance, experts say spring parasite control is more about reducing the levels of pasture contamination than curing animals.
"Only 5% to 10% of parasites in the total system are actually in cattle at any given time," says Frank Hurtig, director of Merial Veterinary Services. "A single cow can pass millions of parasite eggs during the grazing season, which is why the remaining 90% to 95% of parasites end up on pastures."
According to Hurtig, targeting parasites in the spring hits them at a key stage in their life cycle and helps keep cattle from becoming a factory for parasites. In turn, this reduces the number of parasites on pastures and helps producers be proactive in avoiding losses or reducing productivity.
"Many cattle producers only control parasites at the end of the grazing season. But at that point they've already lost growth and productivity, and contaminated the pasture with even more parasites," says Bert Stromberg, parasitologist and professor, University of Minnesota. "If producers are only going to treat once, it should be at spring turnout."
One mistake northern producers make is skipping a spring treatment because they believe a cold winter has taken care of parasites or that one fall treatment is enough to protect animals all year long.
In fact, parasites can and do survive winter on pastures. So don't mistakenly think that you've solved your parasite problem with one treatment in the fall or you'll miss the parasites that are there as cattle begin the grazing season.
Research in Oregon revealed that parasites were transmitted even during freezing temperatures. If parasites weren't picked up in winter, they were able to survive until spring. Stromberg says snow actually helps them survive because it insulates parasites and protects them until spring.
Hurtig explains that parasites like Ostertagia, also known as brown stomach worm, can survive winter in the lining of a cow's stomach in an inhibited juvenile state. But they also can burrow into the soil where they are protected from severe temperatures.
"When warm weather arrives, infective juveniles migrate onto the grass where they are picked up during grazing," Hurtig says.
While producers may never be able to completely eradicate parasites, Stromberg says they can reduce the numbers. That's why he says it's critical cattle producers reduce pasture contamination.
"With spring treatments, the parasites are removed from the host, so they never have the chance to contaminate the pasture," says Stromberg. "If you can do that, you can go longer with fewer parasites in cattle and fewer losses."
"Spring parasite control should be a part of every cattle producer's management strategy. It helps cut pasture contamination and prevent losses," says Hurtig. "Producers should consult with their veterinarian on how to incorporate spring parasite control into their management plan."