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From: TSS ()
Beef News The animal, a heifer, was sent to a Nebraska feedlot, and then was slaughtered at a Nebraska facility. APHIS indicated the animal presented a negligible risk since scientific data indicate that two BSE-positive animals rarely originate from the same herd. "Even at the height of the BSE epidemic in Britain, it was extremely rare to find a cohort at risk for the disease," APHIS spokeswoman Andrea McNally told Meatingplace.com. APHIS spokeswoman Karen Eggerg added that the data on cohorts is based on "years of observation" rather than clinical studies, and indicated that one theory why two animals from the same herd are rarely BSE-positive is that prions, the misfolded proteins associated with BSE, generally are clumped together as a result of their sticky nature, and therefore aren't evenly distributed in feed. After discovering the infected bull, a 79-month-old animal from Alberta, the Canadian Food Inspection Agency focused on cattle born in the same herd within 12 months. The bull became emaciated last winter and subsequently was earmarked for Canada's National BSE Surveillance Program. http://www.meatingplace.com/MembersOnly/webNews/details.aspx?item=17765 funny, i must be slipping, i did not see this on any of the usda/aphis updates. ITEM 6 – BARB CASE CLUSTERS 39. Professor John Wilesmith (Defra) updated the committee on the BSE cases born after the 1996 reinforced mammalian meat and bone meal ban in the UK (BARB cases). Around 116 BARB cases had been identified in Great Britain up to 22 November 2005, mostly through active surveillance. BARB cases had decreased in successive birth cohorts, from 44 in the 1996/1997 cohort to none to date in the 2000/2001 cohort. However, 3 BARB cases had been identified in the 2001/2002 cohort. Backcalculation of the prevalence of BARB cases indicated a drop from 130 infected animals per million (95% confidence interval 90-190) in the 1996/1997 cohort to 30 infected animals per million (95% confidence interval 10-60) in the 1999/2000 cohort. A shift in the geographical distribution of BSE cases, from the concentration of pre-1996 BSE cases in Eastern England to a more uniform 14 © SEAC 2005 distribution of BARB cases, had occurred. However, it appeared that certain post-1996 cohorts had a higher exposure to BSE in certain areas for limited periods. Several clusters of BARB cases within herds had been identified (5 pairs, 2 triplets and 1 quadruplet). 40. A triplet of BARB cases in South West Wales had been investigated in detail. The triplet comprised 2 cases born in September and October 2001 and a third in May 2002. The animals born in 2001 were reared outdoors from the spring of 2002 but the animal born in 2002 had been reared indoors. Further investigation of feeding practices revealed that a new feed bin for the adult dairy herd had been installed in September 1998. In July 2002 the feed bin was emptied, but not cleaned, and relocated. All 3 BARB cases received feed from the relocated bin. This finding suggested the hypothesis that the feed bin installed in September 1998 was filled initially with contaminated feed, that remnants of this feed fell to the bottom of the bin during its relocation, and thus young animals in the 2001/2002 birth cohort were exposed to feedstuffs produced in 1998. No adult cattle had been infected because of the reduced susceptibility to BSE with increasing age. 41. Further investigation of multiple case herds had found no association of BARB clusters with the closure of feed mills. 42. Professor Wilesmith concluded that there is evidence of a decline in risk of infection for successive birth cohorts of cattle. The BARB epidemic is unlikely to be sustained by animals born after 31 July 2000. Feed bins could represent a continued source of occasional infection and advice to farmers is being formulated to reduce this risk. There is no evidence for an indigenous source of infection for the BARB cases. 43. Members considered it encouraging that no other factor, apart from feed contamination, had been identified as a possible cause of BARB cases to date. Members commented that this study suggests that only a small amount of contaminated feed may be required for infection and that BSE infectivity can survive in the environment for several years. Professor Wilesmith agreed and noted that infection caused by small doses of infectious material was consistent with other studies, and it would appear there is little dilution of infectivity, if present, in the rendering system. Additionally it appeared that the infectious agent had survived for 4 years in the feed bin. 44. The Chair thanked Professor Wilesmith for his presentation. 23.2 BSE-infected mad cows in the standing Canadian adult cattle population. very disturbing... tss Environmental Assessment, October 27, 2006 https://web01.aphis.usda.gov/BSEcom.nsf/0/b78ba677e2b0c12185256dd300649f9d?OpenDocument&AutoFramed TSS
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