Remember to deworm

Apr 17, 2023

Beef producers need to look no further than their favorite cattle magazine or website to realize there is a multitude of products available that claim to add value to their animals. Of all these products, one might be surprised to find that the category adding the most value to the cow/calf and stocker operations is dewormers.

According to an Iowa State University analysis of beef cattle production technologies, using a dewormer in the cow/calf herd can add $201 per head to the profitability of the cow. This added value is due to improved weaning weight on the calf and improved pregnancy rate on the cow. For stockers, the added value is $24 per head. This is due primarily to added weight gain.

The impact of worm infection in cattle begins with the grass they graze. Cattle consume forages that are infested with worms as soon as they are turned out to green grass. Worms on grass are resilient, and they can survive cold winter temperatures as well as hot, dry conditions in the summer. Once consumed by cattle, worms damage the gut lining and cause alterations in nutrient digestion. The primary effect is a decrease in feed intake. Nutrient absorption can also be negatively affected by parasitic infections. Therefore, not only is food intake affected, but the absorption of nutrients is decreased as well. This can lead to deficiencies in weight gain, milk production, and reproduction.

Worms also affect cattle health. The immune system recognizes worms as parasitic invaders and will work to protect the animal from this attack. When this happens, immune resources usually available to fight viruses and bacteria are redirected toward fighting the parasitic infection. It is a good idea to ensure that cattle are worm-free before vaccinations to allow vaccines to properly immunize cattle against viruses and bacteria.

In a study published in “The Bovine Practitioner” to assess the health and performance benefits of deworming cattle on grass and at feedlot entry, stockers that were strategically dewormed with Safe-Guard before grass turnout and again at 28 and 56 days post-turnout were, on average, 53 lbs. heavier after 118 days than steers that were not dewormed. Upon feedlot entry, steers were either dewormed again with Safe-Guard or were not dewormed. Cattle that were dewormed on pasture as well as upon feedlot entry were, on average, 130 lbs. heavier at the end of the feedlot phase (an additional 121 days) than cattle that were never dewormed. Cattle that were dewormed were healthier as well. Those that were dewormed on pasture and prior to feedlot entry had 2% morbidity and no death loss, while cattle that were not dewormed had 18% morbidity and 2% death loss.

For these reasons, deworming should be considered the foundation of any health and nutrition program. It is best to strategically utilize dewormers to stay ahead of the worm’s life cycle. In mature cows, it takes 6–8 weeks for worms that are ingested from grass to begin to shed eggs back onto the pasture. If cows were dewormed after a killing frost in the fall or winter, they should be worm-free until they are exposed to green grass again. Therefore, the best time to deworm is 6–8 weeks after green-up. For stockers, the life cycle from worm ingestion to egg shedding is 4–6 weeks. Therefore, stockers should first be dewormed prior to grass turnout, and then again 4–6 weeks later. In some cases, a third deworming treatment 4–6 weeks after the second treatment may be necessary.
Safe-Guard 0.5% pellets (Item #6419) are a safe and highly effective option to deworm without having to gather cattle for processing through a chute. Safe-Guard pellets can be mixed with feed and fed at a rate of 1 lb. per 1,000 lbs. of body weight. One 25-lb. bag of Safe-Guard pellets will treat 25,000 lbs. of cattle.

One way to ensure dewormer efficacy is through a Fecal Egg Count Reduction Test (FECRT). These FECRTs analyze egg counts in feces as a measure of worm load in that animal. A FECRT can help producers determine if their cattle need to be dewormed and if their deworming program is effective. To order FECRT kits, contact your local Co-op livestock specialist or Merck Animal Health representatives Justin Hull at (541) 419-3021 or justin. or Kevin Johnson at (903) 681-5893 or

Deworming is the most important thing we can do to enhance profitability in cow/calf and stocker operations. To best utilize these tools, be sure to use a quality dewormer and work with the worm life cycle to keep cattle productive through the entire grazing season.

For more content like this, check out the latest issue of The Cooperator.

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