Keith, et. al., This just came in on one of the lists that I monitor for infectious diseases. It pertains to the question on bovine semen and the possibility of transmitting BSE/mad-cow. It is so timely that I wonder if someone on the biofuels list could have sent the query -- I did not.
Derek ----- Original Message ----- From: "ProMED-mail" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Monday, January 22, 2001 3:14 AM Subject: PRO/AH> BSE: safety of cattle semen > > BSE: SAFETY OF CATTLE SEMEN > ************************ > A ProMED-mail post > <http://www.promedmail.org> > ProMED-mail is a program of the > International Society for Infectious Diseases > <http://www.isid.org> > > [see also: > 1996 > ------ > BSE: maternal transmission tests neg. 19960516.0921] > > > [ProMED-mail received a query on the possibility that artificial > insemination (AI) might play a part in the epidemiology of BSE. Ray Bradley > & Ralph Blanchfield kindly responded as follows. - MHJ] > > Date: Sat 13 Jan 2001 > From: Ray Bradley <[EMAIL PROTECTED]> , <[EMAIL PROTECTED]> > > > All world authorities are satisfied that bovine semen is safe. Even UK semen > can be exported to Australia and New Zealand. The OIE has semen on its list > of commodities that can be freely traded even from countries with BSE as > stated in the OIE International Animal Health Code chapter on BSE: > "Regardless of the BSE status of the exporting country, Veterinary > Administrations should authorise without restriction the import or transit > through their territory of the following commodities: a) milk and milk > products, b) semen." (There follows a list of other safe commodities). > > There is a considerable literature on the subject (see ref. below). The main > evidences come from the absence of transmission studies of BSE via semen or > any male reproductive tissue inoculated i/c into mice and epidemiological > studies in the field (that endorses the safety of commercial semen for AI). > > I know of no link between the introduction of AI and the occurrence of BSE. > (Any concern would not be) from the semen itself but rather from > constituents of the diluent, if they were of animal origin and not sourced > appropriately, or became contaminated with BSE agents in any way. The same > goes for instruments if they got contaminated and were re-used. For the most > part disposable instruments are used for other reasons than BSE control. > > AI does not involve the use of bovine pituitary derived hormones. There have > been no reports to my knowledge or evidence of iatrogenic transmission of > BSE into any species by the use of medicinal or biological products. > Pituitrin is now synthetic anyway. Pituitary gonadotrophins if prepared from > bovine pituitaries are prepared from safe sources otherwise they would not > be licensed. > > I am not aware that studies have been published on the presence or absence > of PrP C in male reproductive tissues. The question is irrelevant however > since PrP C is expressed in a wide range of animal tissues (including muscle > and heart for example) in which no detectable infectivity is found in > diseased individuals. Every cell in the body has the genetic capability to > produce PrP C so that is why I think the question is irrelevant. > > I am not aware of any publication that indicates that freezing/thawing > converts PrP C into an infectious form. If it did I do not think I would > like to go out on cold days or get things from the fridge! BSE is not a > familial disease. In fact, there is no animal TSE that is the direct > equivalent of familial CJD in man. The epidemio-logical studies referred to > above indicate clearly that even bulls that develop BSE have a similar > incidence of BSE in their adult female offspring as do healthy bulls without > BSE. BSE is a largely or entirely a feed-transmitted disease. > > I cannot believe that in this era anyone can propose that semen transmits > BSE, even though there are no controls on it (other than that semen from > bulls that get BSE is destroyed along with the bull) yet there are controls > on feed, and where these are properly enforced (UK and Switzerland) the BSE > epidemic is in continuous decline; yet where they are not, or have not been > until recently, (Germany, Spain, France, Ireland, Portugal) the epidemics > are increasing. I really do believe that at this time countries should put > in the greatest of efforts to secure the safe feeding of ruminant and other > species rather than worry too much about semen. Ours from the UK has gone > all over the world! > > It also may be of interest that bulls kept for commercial AI do not return > to stud until around 6 years old after the results of progeny testing are > complete. Since the mean incubation period of BSE is 5 years it is > improbable that a bull will develop develop clinical signs of BSE whilst at > stud and collections are being made. > > (The hypothesis could be tested) by introducing high titre infected BSE > brain material into the uterus of a BSE free heifer and waiting for 7 years > to see if BSE develops and if the incubation period is longer or shorter > than if the same dose is given by the oral route. However, this is a purely > academic exercise of no practical value. > > --- > Ray Bradley > Ministry of Agriculture, Fisheries & Food > London, UK > <[EMAIL PROTECTED]> > <[EMAIL PROTECTED]> > > Reference: > ------------ > Bradley R and Wilesmith JW (1993). B Med Bull 49, 932-959 Opinions of the > EC Scientific Steering Committee (visit their website) Wrathall A E (2000). > Livestock Production Science 62, 287 - 316 (10 columns of references in > this). > > -- > ProMED-mail > <[EMAIL PROTECTED]> > > [Apropos, I received among other comments similar to Ray«s but in less > detail. The following was received from Ralph Blanchfield: > > Wilesmith et al, Bovine spongiform encephalopathy: Epidemiological Studies, > Vet Record, 1988, 123, 638-644. > > On checking that paper, I found my recollection was correct that AI played > no part in BSE: > > "The analysis of the records of purchases of animals and the investigation > of the pedigrees of the sires used, particularly in closed herds, provided > conclusive evidence that BSE was not introduced into Great Britain by > imported cattle or disseminated via semen". - MHJ] > ................................mhj/es/jw > > *##########################################################* > ProMED-mail makes every effort to verify the reports that > are posted, but the accuracy and completeness of the > information, and of any statements or opinions based > thereon, are not guaranteed. The reader assumes all risks in > using information posted or archived by ProMED-mail. 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