OPPCONCERNED SHEEP BREEDERS SOCIETY
OPP ERADICATION PROJECT EXPANDING NATIONWIDE
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A TYPICAL OPP EWE
“Let’s suppose that I have a good ewe lamb that I breed to lamb at two years of age. She gives me a single, a lovely strong lamb. I forgive her for giving me a single since it is her first and she is a twin herself. Next year I get twins from her. Those are also nice but not quite as good as the previous one. That is assumed natural since they are twins. Mother is now three and since she raised twins she is not in as good a condition going into breeding as she was the previous year. In next lambing—she is now four—she twins again and this time the twins are born a good size but fail to thrive. And mother is positively thin after raising these two. At this time many would decide to sell the ewe, either (hopefully) to slaughter or to someone looking for cheap breeding stock. After all, the ewe is only 4-1/2 years old. If she has been sold for breeding, (good buy, she is a twinner and should have a few years left) she will probably be dead two years later. This would be a typical OPP ewe.”
STEFANIA DIGNUM (1945—2007)
RENOWNED ICELANDIC BREEDER
“THE SHEPHERD” MAGAZINE, 1989
Long before the words OVINE PROGRESSIVE PNEUMONIA ever hit the popular press, large numbers of cull ewes were purchased off the Western range as low-cost replacements for Midwestern flocks, the theory being that those ewes could be productive for a few more years under more intensive management. The combination of OPPv-infected animals (it’s now known that nearly half of all sheep on the open range carry the OPP/maedi-visna virus) with the close confinement of winter lambing created a perfect storm . . . 45% of Midwestern flocks are now infected, and the virus is common throughout North America.
By the late 1970s, producers wanting to address OPP were beginning to learn that there was more they could do besides just “cull the lungers.” And then, in 1990, a small group led by Wisconsin science teacher and commercial producer Jim Schultz, along with his veterinarian Dr. Bob Leder, formed the OPP CONCERNED SHEEP BREEDERS SOCIETY. Restocking from within after culling heavily, Jim had difficulty locating OPP-negative rams so a priority of the organization was to establish a network of like-minded producers. Word spread (“The Shepherd” magazine published our annual roster during the early years) and before long OPP Society members from all over the U.S. and Canada were learning from each other and collaborating with researchers.
Today, thanks to groundbreaking USDA research into modes of transmission of the OPP virus, producers in Minnesota have demonstrated that eradication can be accomplished without costly orphan rearing of lambs or premature culling of test-positive ewes that remain productive. The OPP Society continues to serve as an educational conduit for this important work, and as a networking hub for producers and veterinarians concerned about OPP and the related condition in goats (CAE, or caprine arthritis encephalitis). When requested, the Society provides active support for members who are working to eradicate these insidious diseases.
OPP can be as obvious as Stefania Dignum’s Description of a Typical OPP Ewe (sidebar). Or OPP can be more subtle, affecting the udder, joints and nervous system as well as the lungs. The indirect effects of pulmonary compromise alone can be significant on the whole animal, resulting in a negative impact on productivity. On the next page is a GENERAL FACT SHEET courtesy of Dr. Cindy Wolf who recently retired from the University of Minnesota and now leads an ASI-funded eradication project building on the work done in Minnesota, but be sure to check out the entire site. Most of the material here is also available in PDF format. (Click here for free download of Acrobat Reader, which is needed to open the PDFs.)
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