Cattle producers need to look no further than their favorite cattle magazine or website to realize that there are a multitude of products available that claim to add value to their cattle. Of all these available products, one might be surprised to find that dewormers are the category that adds the most value to cow/calf and stocker operations. According to an analysis of beef cattle production technologies, using a dewormer in the cow/calf herd can add $201/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/head. This is due primarily to added weight gain.

The impact of worm infection in cattle begins on grass. Cattle consume grass infested with worms as soon as they turn out to green grass. Worms on grass are resilient; they can survive cold winter temperatures and hot, dry conditions in the summer. Once consumed by cattle, worms damage the gut lining and cause alterations in nutrient digestion. The primary effect of this is a decrease in feed intake. In addition, nutrient absorption can also be negatively affected by parasitic infections. Therefore, not only is nutrient intake decreased, but the absorption of nutrients is also decreased. This can lead to reduced 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, the immune resources that are usually available to fight viruses and bacteria are redirected toward fighting parasitic infections. Because of this, it is a good idea to ensure that cattle are worm-free before vaccinations to allow vaccines to immunize cattle against viruses  and bacteria properly.

In a study to assess the health and performance benefits of deworming cattle on grass and at feedlot entry, stockers that were strategically dewormed with Safe-Guard dewormer before grass turnout and again at 28- and 56 days post-turnout were 53 pounds 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 and upon feedlot entry were 130 pounds 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. Cattle that were dewormed on pasture and before feedlot entry had 2% morbidity and 0% 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 ingested from grass 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 be dewormed before grass turnout, and then again 4-6 weeks later. Sometimes, a third deworming treatment another 4-6 weeks after the second treatment may be necessary.

One way to ensure dewormer efficacy is through a Fecal Egg Count Reduction Test (FECRT). A FECRT analyzes egg counts in feces as a measure of worm load in that animal. A FECRT can help producers determine 1) if their cattle need to be dewormed, and 2) if their deworming program is effective. Fecal kits are available through your local Sioux Nation or Merck Animal Health representative.

It is important to remember that not all dewormers have equal efficacy. Through FECRT testing, it has been found that fecal egg counts are reduced by over 98% after the use of benzimidazoles, or “white wormers” such as Safe-Guard. Pour-on and injectable avermectin dewormers, however, only reduce fecal egg counts by about 60%. This means that many worms are still causing damage in the gut and are shedding eggs on pasture, leading to greater worm infection across the herd. An effective deworming is defined as a reduction in fecal egg counts of 90% or more. Therefore, pour-on and injectable dewormers are not effective in deworming cattle, while white wormers are still highly effective.

Deworming is not only important; it 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 and in the feedlot as well.

REFERENCES

Lawrence, John D. and Maro Ibarburu. 2007.
Economic analysis pharmaceutical technologies in modern beef production in a bioeconomy era. http://www2.econ.iastate.
edu/faculty/lawrence/documents/Pharma2007.pdf

Smith, Robert A., Karen C. Rogers, Scott Huse, et al. 2000. Pasture deworming and (or) subsequent feedlot deworming
with fenbendazole. I. Effects on grazing performance, feedlot performance, and carcass traits of yearling steers. The Bovine
Practitioner 34(2):104-114.

Fecal Egg Count Reduction Database. Data on file.