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Working Ranch April/May 2016

REFUGIA REALITY You and your veterinarian need to have a long chat about this emerging parasite control strategy It’s a mild, windy day this spring. Cows are grazing alongside their calves in pastures that are fresh with new season growth. A rancher wishes for a little more rain to ensure the grass continues to grow, but otherwise he is pretty content to gaze out the pickup window or smile in the saddle at the beauty of his cow herd. Little does he know there are predators scoping out his prized bovines. New calves are unaware of the dangers that lurk in the warm spring soil. Older cows might survive the threat but whose job is it to protect cattle from nature’s natural parasite? Spring is the time to manage a sound parasite control program. When new calves are grazing they are susceptible to worms and parasites that are looking for a perfect host. Deworming is a common routine for ranchers and the spring season is the time to get rid of larvae invading those lush eye-appealing pastures. Mike Hildreth is a Professor in Veterinary Parasitology at South Dakota State University. He says dewormers protect cows and calves that are grazing and if a rancher can control parasites they can gain up to 15 pounds on average gain per head, even in the northern Plains. Deworming is not only important to the animal’s health but also to a rancher’s pocketbook. “In the northern Plains, the fi rst thing worth knowing is if cattle parasite control is worth messing with,” he says. “I’ve spent a fair amount of time fi guring out ways to measure losses in commercial herds in South Dakota. If you take a 100-day grazing season, pencil it out and develop a plan, I was fi nding that most producers were underestimating the value of a parasite control program.” During producer meetings, Hildreth has learned ranchers are concerned about drug resistance of internal parasites to worming products. Controlling worms, if done at the right time and with the right amount of product, is cost effective, he says. The climate of the northern Plains lends itself to good worm control and increases natural effectiveness. Hildreth says there is also an increase in selectivity toward resistance in this region. The answer is to use a refugia program; otherwise, he says it’s a matter of time before a rancher will notice resistant worms becoming a problem in their herd. “The selective pressure for resistance is different here,” he says. “It’s not rocket science but we have a fairly short grazing season compared to cattle in the southern region of the U.S. They can graze much longer in Louisiana, for example, which also gives worms BY RHONDA MCCURRY Green grass… the perfect hiding place for those pesky bovine parasites. SONYA SHAW 44 I WORKING RANCH I APRIL / MAY 2016


Working Ranch April/May 2016
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