Deworming cows and calves in the spring is a smart business move for producers looking to earn more profits. A representative study documented an advantage of at least 20 pounds in weaning weight of calves from cows treated for parasites over controls.

“Spring treatment tops my list for smart parasite control strategies,” says Dr. Bert Stromberg, parasitologist and professor, University of Minnesota College of Veterinary Medicine.

“Producers get more production advantages by controlling parasites in the spring than only at weaning. With spring treatment, cattle can grow without a parasite load holding them back.”

He says the best strategy is to treat cows at turnout and then process calves at about 8 weeks of age, when they start grazing for themselves and picking up parasites.

“Treating the cow is extremely important to the welfare of the calf,” Dr. Stromberg says. “We find that the health of the cow significantly impacts the calf’s success during the first half of the grazing season. A cow that is parasite-free produces more milk, which means better gains for the calf.”

Spring parasite control also is a strategic way to reduce overall long-term parasite problems.

“Controlling parasites in cows prior to turnout reduces pasture contamination. This is especially effective in Northern climates where cold winter temperatures can reduce parasite populations on pastures,” says Dr. James Hawkins, Consultant for Merial Veterinary Professional Services.

Cows and calves are not just vectors for parasites — they are multipliers that can pass millions of eggs during the grazing season. Parasite control reduces pasture contamination and prevents episodes of illness or reduced productivity.

“Parasites affect cattle in numerous ways. Heavy parasite loads may reduce an animal’s ability to produce a strong humoral and cell-mediated immune response, making vaccines less effective,” Dr. Hawkins explains. “That’s a one-two punch because calves that face health challenges are more likely to weigh light at weaning.”

Products used in spring should control key parasites, such as Ostertagia ostertagi (brown stomach worm), liver flukes and any other parasites of local concern.

“But cattle move parasites throughout the country, especially when drought forces producers to liquidate herds,” Dr. Hawkins says. “And with parasites such as liver flukes, a producer can’t always tell just by looking which animals are infected.”

Cattle infected with liver flukes can cost producers in reduced pregnancy rates, weaning weights and rate of gain. Not all parasite control products control liver flukes, so producers need to make sure they use a product labeled for liver fluke control, such as IVOMEC® Plus (ivermectin/clorsulon).

Producers using IVOMEC Plus this spring also can take advantage of the IVOMEC Challenge. The challenge allows producers to prove to themselves — risk-free — that spring parasite control in cows and calves yields enough extra pounds at weaning to cover the cost of treatment and more.

“Producers should definitely control parasites in cows and calves in the spring,” Dr. Stromberg advises. “The return on investment can be significant, more than paying for the cost of treatment. Producers can see an increase in weaning weights and that is ultimately how we get paid in this business.”

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