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Sides: Parasite control should be a top priority for livestock producers

by Wyoming Livestock Roundup

One of the most important technologies for producers to utilize is for controlling parasites, according to Zoetis Nutritionist Gary Sides.

“Controlling parasites is more important than implants, beta agonists, ionophores, vaccines and probiotics,” he says. “It is the number one technology we use from birth to slaughter.”

When comparing the impact of external bugs like horn flies and the body louse to internal parasites, Sides notes that internal parasites can have a major impact on production.

“If I take a fecal sample and dilute it, I might find parasite eggs,” he says. “It might not look too bad, but there could be 50,000 adult parasites in the gut of our animals.”


When looking at the potential effect of parasite on livestock, Sides adds, “Parasites affect everything from the immune system and feed intake to digestion.”

Cattle infected with parasites may not respond to vaccines or antibiotics. They may nutritionally suffer and feed intake will likely increase.

“It’s a triple threat, which is why parasites are a producer’s number one risk for loss,” he says.

In analyzing data from across a variety of companies, Sides says that correctly deworming cattle can result in increased yearling gains from 10 to 90 pounds.

“That’s a $45 response from correctly deworming cattle,” he says. “It I do it strictly on grass, the guy who buys my cattle will benefit because there will be fewer pulls, less death, better gain, better efficiency and higher quality grade.”

Managing parasites

Sides notes that parasites can be managed with either an internal or an external vaccine.

“Internal parasites cause more damage than externals, so I’m going to focus my program on killing the internal bugs,” Sides recommends. “Injectable drugs work better than a pour-on. Pour-on is better for the externals.”

Six studies across a variety of companies compared branded products to their generic counterparts, and Sides said the result was staggers.

Cost analysis

“Only one of the six generic drugs performed as well as the pioneer, branded product. The other five were one-fourth or one-fifth as efficacious,” he says.

Looking at the cost of buying branded products versus generic drugs, Sides looks at the cost of treating a 200-pound calf.

“For a generic product, I need 10 cubic centimeters (CCs) of the drug,” he says. “I need two CCs of Dectomax injectable. The cost of the generic is one cent per CC. Dectomax is 25 cents per CC. My cost for the generic is 10 cents per head, and it is 50 cents with the branded product. It’s five times more expensive to use the Dectomax.”

At a minimum, Sides notes that the differential of 40 cents per head can be regained by adding only one-quarter of a pound of gain to the animal.

“I have to make up one-quarter pound of gain in six months for the branded drug to be worth it,” he says. “I can do that. It’s worth it for the cost versus value.”

Long range

Sides also notes that while long-range products are available, promising longer protection for animals, they may be detrimental.

“We don’t see overdoses with these drugs because it’s too expensive to overdose, but what we may see is under-dose or sub-therapeutic concentrations,” he says. “If we see that, we encourage the development of resistant parasites.”

Sides further noted that long-range products have been show to leave sub-therapeutic levels of the drug in the animal from day 25 to day 75. The first 25 days after the dose results in control of many parasites, but the remaining bugs are more likely to develop resistance.

“I’m exposing those parasites to sub-therapeutic doses,” he says. “I see resistance problems when we look at timing versus convenience. If I can give a product two months in advance and it still lasts, that’s convenient. But is it worth the resistance?”

Sides comments, “Three parasitologists who have worked for USDA all say, if we want to develop resistant parasites, use long-range drugs, generics or pour-ons.”

Sides spoke during a late-April 2016 presentation sponsored by Superior Livestock and Zoetis.

Saige Albert is managing editor of the Wyoming Livestock Roundup and can be reached at

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