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Beef Management Tips: Deworm Strategically

Livestock Update, May 1999

John Hall, Animal and Poultry Sciences, Virginia Tech

Old habits are hard to break! At some time, most of us got into the habit of deworming cows and calves at the pre-breeding or turnout working. However, research from Virginia Tech and other universities have demonstrated this is the wrong time to deworm. Internal parasite populations are low in the spring and continue to increase into early summer. For maximum bang for the buck, you need to hold off deworming until late June or early July. Then you should deworm calves at the proper interval. Depending on the product used it can be every three to 10 weeks or no additional dewormings. In addition, cows are the wrong animals to deworm. You should buy dewormer, but you should spend your deworming dollars on calves and 2 and 3 year-old cows. Mature cows build immunity to worms, so populations of worms are low in cows. These low levels of parasites usually don't make an economic impact on the cows productivity. Cows will still shed some eggs, and these eggs will infest calves. However, deworming the cows to prevent the shedding of these eggs is not an economical solution. If calves are dewormed strategically according to the product directions, the few eggs that cows shed will not have an impact on the calves.

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