Money-Making Reasons to Control Parasites This Spring

Treating cows for parasites at spring turnout yields higher weaning weights and more

DULUTH, Ga. — Jan. 26, 2009 — Spring parasite treatments can help add weight to both calves and bank accounts. New university data has concluded that of all the pharmaceutical technologies examined, parasite control in cow herds had the greatest effect on breakeven prices — providing a value of $201 per head.1 This effect was derived using only weaning rates and weaning weights.1,2 Producers can get their share of this return by incorporating a spring parasite control treatment into their operation.

Dr. Frank Hurtig, director, Merial Veterinary Services, says cow/calf producers, who use parasite treatments in the spring on their spring-calving herds, can expect benefits such as:

Increased weaning weights3-5

Boosted reproductive performance 6

Reduced pasture parasite loads5,7

Reduced parasite infections in calves as a result of reduced pasture contamination by cows7

“Spring parasite control is more of a production efficiency issue than an animal health issue,” says Dr. Michael Hildreth, parasitologist and professor, South Dakota State University. “Parasites affect the production parameters that producers care about most, such as weight gain, feed efficiency, carcass quality, conception rates, milk production and immune response.7 Spring treatments can help gain efficiencies in these areas.”

Studies spanning the last 25 years have shown a statistically significant increase in weaning weights when cows and calves were treated in the spring for parasites with IVOMEC® (ivermectin) Brand Products.3,4

Past research also has shown cows treated for parasites at turnout have shown more than a 12 percent reproductive advantage when compared with untreated cows.6

Dr. Hurtig says though cattle producers in cold-weather climates may think the winter will kill parasites, they should not neglect spring parasite control.

“Parasites overwinter in cattle and in the soil, even in Northern climates,”7 Dr. Hurtig says. “Soil temperatures are warmer than air temperatures, allowing parasites to survive.7 Plus, cold weather slows parasites’ metabolism, actually helping them to remain viable longer.”7,8

Not only can parasites survive the winter, but research has shown that cattle can become re-infected even when the air temperature is below freezing.9

“This means that cows can start getting re-infected with worms earlier than people may think,” Dr. Hurtig says. “In the spring, cows are at a higher risk than other times of year for not only getting infected but also to contaminate the pasture and increase the worm burden of their own calves.”7

By treating cows at spring turnout, producers can kill the parasites already in the cow and those the cows pick up for the duration of time, based on its label, the endectocide is effective against each parasite. Spring treatments can help reduce parasite pressure for calves, too. In fact, Dr. Hildreth says parasite infection levels can be significantly lower in calves if cows were treated with an endectocide in the spring.7

“Parasites overwintering on pasture have to get into cattle early in the spring to maintain their life cyle.7 If they can’t get into cattle, parasites on pasture starve to death,”7 he says. “That means that spring treatments not only protect the cow, they attack the parasite population at its weakest link, which means fewer overall parasites in cattle and on pastures.”7

But not all parasite control products will accomplish these results. Based on their labels, drench-type or white wormers have no residual activity.10 Endectocides, such as IVOMEC Brand Products, are effective for 14 to 28 days depending on the parasite and product used.10 IVOMEC offers four proven formulations to meet every producer’s parasite control needs, and all IVOMEC Brand Products are backed by Merial’s 100% Product Satisfaction Guarantee.

High input costs and an unstable economy may have producers looking to skip a season or even a year of parasite control, but Dr. Hildreth advises against that plan.

“For example, with vaccines you can choose to skip vaccination and maybe luck out if your calves don’t encounter that pathogen. But, with parasites, they are there every year and if you don’t control them they will cost you money,” Dr. Hildreth says.

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 5,400 people and operates in more than 150 countries worldwide. Its 2008 sales were more than $2.6 billion. Merial Limited is a joint venture between Merck & Co., Inc and sanofi-aventis. For more information, please see


IVOMEC Plus (ivermectin/clorsulon): Do not treat cattle within 49 days of slaughter. Do not use in dairy cattle of breeding age or in veal calves. IVOMEC (ivermectin) Pour-On: Do not treat cattle within 48 days of slaughter. Do not use in dairy cattle of breeding age or in veal calves. IVOMEC 1% Injection for Cattle and Swine: Do not treat cattle within 35 days of slaughter. Do not use in dairy cattle of breeding age or in veal calves. Do not treat swine within 18 days of slaughter. IVOMEC EPRINEX® (eprinomectin) Pour-On for Beef and Dairy: No meat or milk withdrawal is required when used according to label. All IVOMEC Brand Products: Do not use in other animal species not on the label as severe adverse reactions, including fatalities in dogs, may result.

1Lawrence JD, Ibarburu MA. Economic analysis of pharmaceutical technologies in modern beef production in a bioeconomy era. 2009 Iowa State University.

2Lawrence JD, Ibarburu MA. Economic analysis of pharmaceutical technologies in modern beef production. 2007 Iowa State University.

3Wohlgemuth K, et al. Relationship between weaning weights of North Dakota beef calves and treatment of their dams with ivermectin. Agri-Practice 1988:23-26.

4Ciordia H, et al. Effect of ivermectin on performance on beef cattle on Georgia pastures. Am J Vet Res 1984; 45:2455-2457.

5Myers, GH. Strategies to control internal parasites in cattle and swine. Journal of Animal Science 1988;66:1555-1564.

6Stromberg BE. Production responses following strategic parasite control in a beef cow/calf herd. Veterinary Parasitology 1997;68:315-322.

7Hildreth M. Economics and control of cattle-worms in beef cattle: a northern perspective. Academy of Veterinary Consultants Meeting. December 2008.

8Stromberg BE. Environmental factors influencing transmission. Veterinary Parasitology.

9Rickard LG, Zimmerman GL. The epizootiology of gastrointestinal nematodes of cattle in selected areas of Oregon. Vet Parasitology 1992;43:271-291.

10Based on data provided in FDA freedom of information summaries.

®IVOMEC and EPRINEX are registered trademarks of Merial.

©2009 Merial Limited. Duluth, GA. All rights reserved. RUMIEGN922 (01/09)


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