Maximize Performance with Strategic Deworming

Using the wrong dewormer on your cow herd could cost you money through production and reproductive losses.

STERLING, Colo. (Oct. 2, 2008) – Pat Owens couldn’t figure out what was wrong with his calves. He used a pour-on deworming product at receiving, but the calves weren’t performing. Rough hair coats, droopy ears and little weight gain were all symptoms that something wasn’t right.

Owens, a cow/calf producer and stocker operator in Sylvania, Ga., pulled fecal samples and sent them to his veterinarian. The results showed the calves were carrying a high parasite load.

“In our area there has been ongoing discussion about which products are better, and which method is more effective,” says Ray Hicks, Screven County extension coordinator with University of Georgia. “I was called in to help and conducted a small comparison at Owens Farms with 25 head.”

Consistent with other studies, Hicks found that using Dectomax® resulted in better weight gains compared to a generic ivermectin product. However, no matter which product you use, including deworming in your animal health practices is an important step.

Importance of deworming

Parasites are found in almost all forage situations, and your cattle are ingesting parasites if they are grazing pastures. Parasites cause numerous problems, including depressed immune systems in cattle, making cattle more susceptible to disease challenges.

According to Gary Sides, PhD, cattle nutritionist for Pfizer Animal Health, Sterling, Colo., parasites require cattle to complete their lifecycle. “The purpose of strategic deworming is to treat cattle in a timely manner to reduce the total parasite load on pasture,” he says. “This reduces total exposure of parasites to all cattle on that pasture.”

John Lawrence, director of the Iowa Beef Center, conducted an economic analysis of pharmaceutical technologies, and found that parasite control in the cow herd has a significant impact on calf production and cost to the beef system. In fact, parasite infestation in a cow herd can cost more than $200 per cow/calf pair through production and reproductive losses.1

“Those internal parasites also suppress appetites, which limits nutrient intake and absorption,” Sides adds. “Reduced nutrition impacts animal performance including gain, feed efficiency, immune response, and reproduction.”

These losses can be minimized by using a dewormer before pasture turnout in the spring, and again in the fall. Rodger Schroeder, manager of Schroeder Operations in Chugwater, Wyo., says deworming in the spring helps clean up external parasites. “In the fall, when we preg-test our cows, we deworm them again. We’ve found that they just do better through the winter when we use Dectomax in the fall.”

But, the decision on what dewormer to use can be as important as deciding to implement a deworming program.

Choosing the right dewormer

According to Sides, a recent trial comparing Durvet, which is a generic ivermectin pour-on, to Dectomax Pour-On was conducted on steers purchased from a single pasture in California. Cattle were fed for 162 days and harvested at a local packing facility.

The study found that at days 14 and 30, fecal egg counts were significantly lower in the cattle treated with Dectomax vs. Durvet. The parasite data also showed Durvet wasn’t as effective at eliminating Osteragia adults (brown stomach worm), killing only 63 percent, while Dectomax killed 94 percent of the adult worms.2

At the end of the study, researchers also found an average of a 22 pound per head increase in live weight in steers treated with Dectomax Pour-On, which in today’s market is worth about $20 per head.3 “The results show that Durvet just wasn’t as effective as Dectomax,” Sides concludes.

Dectomax can produce positive impacts in any type of operation, not just feedyards. “We’ve seen anywhere between a 20- and 50-pound increase in the weaning weights of our calves when we use Dectomax,” notes Schroeder.

“Dectomax may be more expensive than other dewormers. But, at the end of the day if the ivermectin product doesn’t perform, you could be losing $20 per head at the feedyard level,” Sides stresses. “In this instance, price shouldn’t be the deciding factor. It is the performance that matters.” And if parasites are not controlled on pasture cattle, reproductive and weaning weight losses may be even greater.

Pfizer Inc. (NYSE: PFE), the world’s largest research-based pharmaceutical company, is a world leader in discovering and developing innovative animal vaccines and prescription medicines. Pfizer Animal Health is dedicated to improving the safety, quality and productivity of the world’s food supply by enhancing the health of livestock and poultry; and in helping companion animals live longer and healthier lives. For additional information on Pfizer’s portfolio of animal products, visit


1 Lawrence JD, et al, Economic Analysis of Pharmaceutical Technologies in Modern Beef Production. Iowa State University. 2006.

2,3 Pfizer Animal Health. Dectomax Versus Generic Ivermectin Pour-On (Durvet). Tech Notes, New York, NY: Pfizer Animal Health, 2007.

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