Shift in Parasite Population May be Costing You

There’s a new public enemy No. 1 when it comes to internal parasites in cattle and it may be costing you. A new study shows that Cooperia reduces intake and rate of gain.
Cooperia has become the most prevalent internal parasite in U.S. cattle operations according to research data from USDA’s National Animal Health Monitoring Service (NAHMS) Beef 2007-2008 cow-calf survey. The economic impact of Cooperia on cattle productivity, however, has not been studied. Findings from a newly published research study – completed by leading U.S. parasitologists and sponsored by Merck Animal Health – bring to light the negative impact Cooperia can have on productivity if your deworming program is leaving these worms behind.
“For decades, the brown stomach worm, Ostertagia, was believed to be the most pathogenic and economically costly of internal cattle parasites,” says Bert Stromberg, Ph.D., professor of parasitology at the University of Minnesota who assisted with the NAHMS research. “And to their credit, avermectin dewormers, including the popular pour-on products, have done a good job of controlling performance-robbing parasites.”
But over time, the constant removal of brown stomach worms from the animal created an environment more favorable for avermectin-resistant parasites such as Cooperia punctata, explained Stromberg. And because the focus was on the brown stomach worm, the effect of small intestinal worms (Cooperia punctata) on cattle productivity was largely unknown.
In research sponsored by Merck Animal Health, calves infected with Cooperia were compared to parasite-free calves in a controlled 60-day feeder trial.
The study was initiated in the fall of 2009, when two hundred calves with an average weight of 460 pounds were acquired from the Northwestern Arkansas and Northeastern Oklahoma region. The animals were vaccinated, dewormed and acclimated for approximately five weeks on a standard growing ration before the initiation of data collection using GrowSafe® system feed bunks to measure individual intake and gain.
On day 0 and day 14 of the data collection phase, two pens of 40 calves were orally drenched with Cooperia punctata infective larvae. The two control pens of 40 calves each received a drench of tap water. Data collected included biweekly fecal egg counts, daily individual feed consumption and weight gain over the 60 day test period.
The calves free of Cooperia gained weight 7.4 percent more rapidly than infected calves—gaining 3.24 pounds per day versus 3.0 pounds per day. The infected animals consumed 1.5 pounds per day less on a dry matter basis compared to those free of all parasites.
“The results are significant. To put them into perspective, compare this impact to other attributes of production,” said Harold Newcomb, technical service veterinarian for Merck Animal Health who observed the research throughout. “Consider that growth-promoting implants increase rate of gain between 8 and 15 percent. Most cattlemen wouldn’t give up the performance advantages implants provide. But, using dewormer that leaves Cooperia behind could reduce average daily gain by more than 7 percent and diminish, if not nullify, the benefit of your implant program during the first 60 days.”
Given the prevalence of Cooperia identified by the NAHMS cow/calf survey, it is increasingly important that producers work with their veterinarian to test their animals and ensure their deworming program is effective against all of the most prevalent internal parasites including Cooperia.  

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