Combining Classes Of Cattle Dewormers Can Help Reduce Parasite Pressure In Your Herd

The annual springtime battle of reducing internal parasites in your beef cattle herd is underway- and Dr. Harold Newcomb, Technical Services Manager of Merck Animal Health says that best piece of advice that he can give any cattle producer at this time of year is "that whatever dewormer program you are using- you need to check and make sure it is working." Farm Director Ron Hays talked with Dr. Newcomb about what a cattle producer needs to consider when it comes to a proactive cattle deworming strategy

Dr. Newcomb says that several studies by the livestock industry has provided some direction in cattle dewormer resistance. All cattle populations have a few parasites that carry genes of resistance to one or more of the three classes of anthelmintics- or dewormers. Dr. Newcomb told Hays "Basically, what we've found is by using two or more different classes of dewormers- say you use Safeguard and Ivomec (Those would be two classes)- by using those classes of dewormers together we are actually able to cut down the amount of resistant parasites in a population."

He adds that work in Australia with sheep and parasites has shown that by using two or all three classes of dewormers allow you to cut down on the population of resistant worms.

He says that the one group of cattle got a single long acting dewormer while the second group got two classes of dewormer represented by a generic ivermectin pour-on and by Safeguard. The cattle receiving the coordinated two class treatment outperformed the first group with 23 pounds of additional weight gain- and the worm pressure in the pasture was significantly lower in the pasture they were grazing.

One conclusion of the study was that "the weight gain on the trial using two dewormers was coming at the front when the grass was at its best- in other words- the grass was more tender- more nutritious."