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Important New Reasons for Strategic Deworming By Jill J. Dunkel and Leah Schomburg New evidence from USDA indicates that a significant worm burden not only reduces your herd's performance -- it may also reduce the efficacy of your vaccines. Researcher Lou Gasbarre, Ph.D., of Beltsville, Maryland, says the two studies are so recently concluded that the data has yet to be compiled into report form. "We have established proof of concept," Gasbarre says, "that as parasite numbers go up, you see a greater and greater effect on an the ability of an animal's immune system to recognize and respond to something else as a foreign object. In both studies, we've seen an enhancement of the antibody response against our immunizing agent after deworming -- we actually had more circulating antibody. "From what we have seen, the presence of the worms causes the immune system to be out of balance, making it go in one direction. If you remove the worms, the immune system can go back to its natural state," he says. "If you put in a good parasite control program, you have brought the overall herd worm burden down to a level where you'll see an increased vaccine effectiveness." Nutrition, stress and other factors can also play a role in vaccine effectiveness. Gasbarre says dewormers should be offered two to four weeks ahead of the planned vaccination program to ensure the animal's immune system is receptive to a new challenge. Non-handling forms of fenbendazole - like Intervet's Safe-Guard(R) mineral, blocks and feed additives - can be used effectively in such a program. By offering dewormer in a form that is attractive to the animal, producers need not gather cattle twice. "In our minds, it would be to your advantage to initiate the strategic deworming program prior to vaccination," he advises. Dr. Don Bliss of Mid America Ag Research in Verona, Wisconsin, agrees, adding that "effect on immunity appears to be starting in early life." With this in mind, Bliss recommends initiating a deworming program as young as possible. "Cattle face a daily challenge in the pasture. The sooner you get internal parasites under control, the better." Bliss says one area that can capitalize on controlling internal parasites is ranchers that retain ownership. "If you can treat early on in the calf's life, you will see better health in the future." It is also very important at the stocker phase, says Bliss. "Stockers grazing for 50 to 150 days can become highly exposed. They are generating a lot of parasites." Bliss recommends if cattle are grazing 100 to 110 days or less, to deworm at turnout, and again at three to four weeks after turnout. Cattle turned out longer, should be dewormed again another four weeks later. "It's a 0/4/8 program (deworm at turnout, four weeks and eight weeks later)," says Bliss. "Research shows you reduce the parasite challenge by 80 to 90 percent by doing this." In order to eliminate unnecessary handling of cattle, Bliss recommends deworming pasture cattle through mineral, blocks or cake. "Not every calf will eat mineral that first day of treatment, so spread the dewormer out over three or four days to deworm the entire herd." Bliss believes it also pays to deworm high performance cattle in the feedyard. "As standards for cattle go up, deworming becomes more important," he says. "It doesn't take a heavy parasite load to hurt a calf that has the potential to gain 3 1/2 to 4 pounds a day." More and more feedyards are following the hog industry in deworming in the arrival ration instead of at processing. "If the cattle are bunk broke, deworming in the ration once is sufficient. However, if the cattle are not accustomed to eating from bunks, spread the dewormer top-dressing over a few days time. With his first bite, he starts to deworm." Portions of this article were reprinted with permission from Your Performance Partner magazine. |
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