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Virginia Cooperative Extension -
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Sheep Update

Livestock Update, June 2006

Dr. Scott P. Greiner, Extension Animal Scientist, Sheep, VA Tech

Tips for Sheep Internal Parasite Control
Internal parasites are a potential source of economic losses for sheep producers during the spring and summer months.  Parasitic infestation can result in decreased production of ewes and lambs on pasture through reduced milk production and poor weight gains, and even mortality in extreme cases.  The most significant parasite impacting sheep in Virginia is Haemonchus contortus.  These worms thrive under warm and moist conditions of late spring and summer, which emphasizes the importance of an effective parasite control program as sheep go to pasture.  Approved dewormers for use in sheep include Levamisole (Levasole and Tramisol), Ivermectin (Ivomec Sheep Drench), Albenazole (Valbazen), and the recently approved Moxidectin (Cydectin Sheep Drench).  Keep in mind that all other products are currently not labeled for sheep, and must be prescribed and administered under veterinary direction.  Following are a few tips for a successful sheep deworming strategy:

  1. Reduce the number of deworming treatments and practice selective deworming, through strategies such as the FAMACHA system.  Deworm only when necessary to prevent development of drug resistance, and deworm only those sheep which warrant deworming.
  2. Cull highly susceptible sheep from the flock.  Research has shown that a small percentage of the flock hosts the majority of the parasites, and these parasites shed the majority of the eggs.
  3. Use pasture management to enhance the effectiveness of a deworming program.  The practice of "dose and move" can reduce the dependence on anthelmentic drugs to prevent and treat parasites by reducing the number of parasites sheep are exposed to.  Using the dose and move technique, sheep are moved to a clean pasture after treatment.  A clean pasture may be one that has been harvested for hay, previously grazed by cattle, or been without sheep for a year.  A clean pasture does not ensure that infective larvae are not present, but has infectivity low enough that susceptible sheep do not become infected rapidly.  A strategic deworming protocol must still be followed after moving the sheep.
  4. Lower stocking rates will reduce the intensity of the deworming program.  Fewer sheep result in fewer shed worm eggs within a given area, thereby reducing parasite loads.  This in turn may reduce the frequency of deworming, and help minimize developed resistance.
  5. Administer the proper dose.  Be sure to estimate the weight of the sheep accurately.  Dose the sheep for the heaviest in the group, not the average.  Dosages given that are inadequate for the body weight of the sheep are not only less effective on decreasing worm loads, but may also enhance parasite resistance to the drugs.
  6. Rotate dewormers annually.  This means that if you used Ivermectin last year, switch to Levamisole this year.  Rotating anthelmentics on an every other year basis will help prevent parasites from developing resistance to the product.
  7. When introducing new sheep to the flock, deworm with products from two different drug classes (such as Tramisol and Ivermectin).  New sheep should be isolated a minimum of 30 days prior to introduction.  Mixing untreated sheep with sheep on the deworming program may destroy earlier efforts to minimize worm loads in the flock, and potentially introduce resistant worms.

Wool Pool Dates Set for 2006
The Virginia-North Carolina Wool Pool has set up collection points and dates for producers wishing to market their wool to Mid-States Wool Growers Cooperative Association based in Canal Winchester, Ohio.  Producers are encouraged to package, handle and store their wool in an appropriate manner in order to maximize the value of their wool clip.  Wool should be packaged by type/grade (ewe vs. lamb wool, long staple vs. short wools, fine vs. medium wools) in plastic bags, and be clean, dry, and have foreign material (straw, mud, manure) removed prior to packaging.  Following is a list of local pool delivery dates, and locations where wool will be picked up:

June 14, 9 AM             Williamston, NC
June 14, 9 AM             Albemarle, NC
June 15, 8 AM             Sparta, NC
June 27, 8 AM             Orange, VA
June 27                        Farmville, VA
June 28, 6 PM              Asheville, NC
June 29, 8 AM             Wytheville, VA
July 6, 8 AM                Christiansburg, VA
July 10, 8 AM              Highland Co., VA
July 13, 7 AM              Rockbridge Co., VA
July 14, 8 AM              Augusta Co., VA
July 18, 8 AM              Clark Co., VA
July 20, 1 PM               Russell Co., VA
July 25, 8 AM              Tazewell Co., VA

To confirm the above dates, and for more information regarding specific times and locations, contact your local Virginia Cooperative Extension Office.

Virginia Ram Lamb Performance Test 2006
A total of 60 rams from 14 Virginia consignors were delivered May 2 to the Virginia Sheep Evaluation Station located at the Shenandoah Valley Agricultural Research and Extension Center near Steeles Tavern, VA.  Consignment numbers and breeds of rams consigned include: 29 Suffolk, 10 Fall Dorset, 12 Winter Dorset, 7 Katahdin, and 2 Hampshire.  The rams began the 63-day test period on May 16, which will conclude July 18.  At the completion of the test, rams will be evaluated for reproductive and structural soundness.  Qualifying rams will sell at the station on Saturday, August 26.  Complete performance information will be available on all rams, including measures of growth performance, ultrasonic estimates of carcass merit, and scrapie resistance genotypes.  For information please contact Scott Greiner, phone

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