Don’t Lose Another Penny to Parasites

Spring parasite treatments have proven returns for cow/calf producers1-4

DULUTH, GA — Jan. 18, 2010 — Cow/calf producers could be losing potential performance and returns if they are not treating cattle for parasites in the spring. But Dr. Frank Hurtig, director, Merial Veterinary Services, says producers can easily stop parasites from feeding on their bottom line.

“By treating cattle for parasites in the spring with a product they can trust such as an IVOMEC® (ivermectin, eprinomectin) Brand Product, cow/calf producers can make the most out of the spring and summer grazing seasons,” he says. “Even if parasite levels are low, or cattle are not showing clinical signs of parasite infections, losses are still possible — even probable.”

Internal parasites cause a decrease in nutritional absorption and digestion.4 Parasites such as the most economically important worm, the brown stomach worm, can suppress the animal’s appetite.5 Therefore, an animal carrying even a subclinical parasite infection is expected to perform more efficiently after parasites are removed.4 Dr. Hurtig says this is especially true for spring-calving cows.

“Cows have the greatest nutritional requirements for the first three to four months postpartum, which unfortunately coincides with the time they are expected to rebreed to stay on a yearly calving schedule,”4 Dr. Hurtig says. “Producers can’t afford to let their cows try and support a calf while the parasite load is taking its toll at the same time they are trying to prepare for breeding season. In this tug-of-war, the parasites will nearly always steal profits.”

In fact, research has shown that parasite control with an IVOMEC Brand Product prior to breeding can increase conception rates up to 5 percent.4

“A 5 percent increase in conception rate is significant when we consider that the cost of an open cow is more than $400 per year6 and a calf conceived on the first day of a 60-day breeding season will be worth $108 more than one conceived on the last day,”7 Dr. Hurtig says.

Studies going back 25 years have shown a statistically significant increase in weaning weights when cows and calves were treated for parasites in the spring with an IVOMEC Brand Product.1-3 Dr. Mike Hildreth, parasitologist and professor, South Dakota State University, conducted research that showed similar results.8,9 He says the weight advantage found was despite the fact that these cattle had very low parasite infection levels.

“The research was conducted in herds in the central part of South Dakota, where we expect to find fairly low worm burdens,” he says. “On average, the parasite-infected calves were losing 10 to 15 pounds per every 100 days on summer pasture.8,9 And, these losses were occurring when egg counts were low, an average of 35 eggs per gram.8,9 If we saw this in areas where parasite levels are low, we would expect to see this same effect, or an even greater one, anywhere else.”

Dr. Hurtig says producers can’t bank on low parasite loads on pastures or harsh winters to help protect their cattle from parasites.

“Even in cold Northern climates, parasites survive winter both in cows and in the pasture,” he explains. “Parasites survive cold winters by working their way into the soil where temperatures remain higher than air temperatures.10 And a protective blanket of snow can actually help preserve larvae through winter.”11

A two-week Oregon study showed that parasite-naïve calves turned out on contaminated pastures during freezing temperatures in winter picked up more than 200,000 worms.12

Dr. Hurtig says that in warmer Southern climates, it is even more important that producers consider a parasite treatment in the spring. The best solution, he says, is that all producers, regardless of geography, talk with their veterinarian about incorporating a spring treatment with an IVOMEC Brand Product into their year-long parasite control program.

“Treating with an IVOMEC Brand Product at spring turnout helps kill parasites in cows and continues to protect against new infections for the length of time the product is effective against each parasite,” Dr. Hurtig says. “This is especially important when we consider that relatively few — only 5 percent to 10 percent — of parasites present are actually inside cattle at any given time. The remaining 90 percent to 95 percent are on pastures.”13

Drench-type or white dewormers are only effective the day of treatment and not against inhibited Ostertagia at the normal dose.14 Conventional endectocides, such as IVOMEC Brand Products, are effective for 14 to 28 days, depending on the parasite and product used,14 which means they control parasites in the animal at the time of treatment and those picked up from spring pasture.

Parasite control in cow herds hads been shown to have the greatest effect on breakeven prices — providing a value of $201 per head.15 This effect was derived using only weaning rates and weaning weights.13 Dr. Hurtig says producers can help get their share of this return, and help stop losses from parasites, by simply starting with a spring parasite control treatment.

“Reproductive efficiency and weaning weights are two key factors to cow/calf producers’ profitability,” he says. “Adding a spring parasite control treatment with an IVOMEC Brand Product can help producers stop parasites from eating away at cattle performance and profits.”

Only Merial offers four proven formulations of IVOMEC Brand Products. All IVOMEC Brand Products are backed by a 100% Product Satisfaction Guarantee. For more information, producers should contact their local Merial sales representative or visit

Merial is a world-leading, innovation-driven animal health company, providing a comprehensive range of products to enhance the health, well-being and performance of a wide range of animals. Merial employs approximately 5,700 people and operates in more than 150 countries worldwide. Its 2009 sales were $2.6 billion. Merial is the Animal Health subsidiary of sanofi-aventis. For more information, please see