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Combination Deworming Programs Can Pay Large Dividends

Feedlot cattle prove performance benefits of reduced parasite loads

By Gary Sides, Ph.D., Cattle Nutritionist, Veterinary Operations, Pfizer Animal Health

Feedlot operators are turning to veterinarians and nutritionists to help prepare cattle for the best defense against fall parasites.

Controlling parasites in the feedlot is not something that we do just for the immune system1 as there are direct performance benefits as well. In fact, research has shown that parasites could cost the industry up to $3 billion annually in lost weight gains, poor feed conversion and increased disease.2 High feed prices greatly magnify these factors. Using a solid deworming program can help operators take advantage of all possible performance benefits.

Poor decisions surrounding appropriate parasite control product selection can end up costing much more in the long run. As a feedlot operator, think of it this way: It only takes approximately one extra pound of gain to make up for the cost of a complete deworming program.

Depending on your geographic location, feedlot cattle will generally experience the best response when dewormed with a broad-spectrum avermectin product. When evaluating what dewormer will be the most effective on a specific group of cattle, consider the following:

• Make sure the product is labeled to kill inhibited Ostertagia ostertagi, one of the most damaging internal parasites — often a weakness of using an oral suspension (drench).3

• Injection site lesions ─ look for a product that leaves little to no trail at the injection site.

• There are no products that are completely effective against all internal and external cattle parasites. There may be cases where an avermectin in combination with an oral suspension may be cost-effective.

To recognize optimal dividends, consider combining a drench and an injectable or pour-on treatment protocol. Your consultants can help you to evaluate if a combination treatment would help improve your cattle’s treatment response.

There are times when there is not any one single parasiticide treatment that will control all parasites perfectly. Avermectins do an excellent job of controlling external parasites and inhibited Ostertagia ostertagi, also known as the brown stomach worm, but may not be as effective against specific intestinal parasites. The oral suspension will do a better job on intestinal parasites and liver flukes, but does a poor job at defending animals against inhibited Ostertagia and has no effect on external parasites. If biting lice have historically been an issue or concern for your operation, you should consider using an avermectin pour-on product. These cattle would probably also respond to an added treatment of an albendazole or benzimidazole drench.

If you are unsure which parasites may be endangering your herd the most, consult your local veterinarian before implementing any new treatment procedures.

Trying to save a dollar on parasite control at processing could easily cost you 20 pounds or more at sale time. Cattle values and the inflated cost of feedstuffs are too high not to realize the added performance benefits possible when using a broad-spectrum deworming program. Evaluate your options with your consultants and choose your deworming products carefully to ensure you are getting the full benefit of each dollar spent.

Gary Sides, Ph.D., cattle nutritionist, technical services, has been with Pfizer Animal Health since 2003.

Before putting his nutritional expertise to work for beef producers, the New Mexico native spent two years as a livestock Extension specialist with Texas A&M University, located in College Station, Texas. Additionally, he was a research scientist with Utah State University. Sides earned his doctorate in ruminant physiology and nutrition from the University of Wyoming and both his Bachelor of Science and Master of Science degrees from New Mexico State University-Las Cruces.

For more information, contact:

Becky Lambert

Pfizer Animal Health


[email protected]

Kori Conley

Bader Rutter


[email protected]

1 Gasbarre LC, Rew RS. Immune response in nematode infected cattle following Dectomax® treatment. June 2002.

2 Bagley C, Healey MC, Hansen D. Beef Cattle Handbook: Internal parasites in cattle. Iowa Beef Center. 1999.

3 Miller, JE. Variable efficacy of benzimidazole anthelmintics against inhibited larvae of Ostertagia ostertagi in Proceedings. Am. Assoc. Bovine Pract. Jan 1994. 26:150-153.