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Question 1: What evidence do you have that OmniGen-AF really works?
Comment: We have accumulated a lot of evidence from several studies which indicate that OmniGen is a useful feed additive. In addition, over 1 million cows in the US are presently being fed this product and results from a wide range of dairy types have been highly favorable. The product is rapidly gaining acceptance internationally. If you have interest in our research please check the two research links below:
Question 2: The manufacturer presents the hypothesis that HBS is caused by a mold
called Aspergillus fumigatus. They have one piece of research that I could find. I could not find anything published. Is there anyone out there that knows if this is plausible? Or is it just hypothesis? I thought clostridium made more sense biologically as the cause of HBS, but maybe some new information has come out that I may have missed.
Comment: At present there are three published papers concerning the possibility that A. fumigatus is associated with HBS. The citations are:
Sockett, D.C., A.I. Brower, K.L. Woods, R.E. Porter, P.N. Bochsler, S.M. Godden, N.E. Forsberg, S.B. Puntenney, and Y. Wang. Hemorrhagic bowel syndrome in dairy cattle: Preliminary results from a case control study. Am. Assoc. Vet. Lab. Diag. October, 2004.
Puntenney, S., Y. Wang, N.E. Forsberg. Mycotic infections in livestock: Recent insights and studies on etiology, diagnostics and prevention of Hemorrhagic Bowel Syndrome. Proc. S.W. Anim. Nutr. Manag. Conf. 49-62, 2003.
Forsberg, N.E. Proc. Prince-Agri Feed Ingredient Conference. 2003.
Forsberg, N.E. Mycotic infections in livestock: development of PCR-based assays and feed additives for hemorrhagic bowel syndrome in dairy cattle. Proc. Wisc. Vet. Med. Association. 2003. pp. 91-100.
Each of these (and other) papers can be accessed at the Newsletters & Publications link. Please note that these are "Proceedings Papers" (i.e., invited papers) and there is some repetition of data in these. There are also six abstracts presented at the Am. Dairy Science Assoc. in 2003 and 2005. Publication in peer-reviewed journals is forthcoming.
At this time, we believe the evidence for a role of A. fumigatus in HBS is very strong. The Forsberg lab at Oregon State University have been conducting a "blind" study with the Wisconsin Veterinary Diagnostic Laboratory since June, 2003. So far, 13 of 16 HBS cows they have sent to us have been A. fumigatus- positive. All case controls (cows dying from other GI disease, n=9) are negative. Of interest, C. perfringens was detected in both HBS and case-control cows. Please note that this study is on-going. So far, results are promising. But, it remains a small pilot study and we are not yet drawing inferences from our results.
Question 3: The researchers claim that there is a PCR test available through Oregon
State. The test is supposed to diagnose HBS due to the detection of aspergillus. Has anyone used this PCR test? Has it been effective (or accurate)? Isn't aspergillus ubiquitous on most dairy farms? In that case, will a positive detection of aspergillus in a cow mean anything?
Comment. We have developed a quantitative PCR test for A. fumigatus in my lab at Oregon State University . We test concentrations of A. fumigatus in feeds and biological tissues/fluids at a cost of $24 for blood and $40 for feeds and tissues. Please note, the assay detects Aspergillus fumigatus DNA and is very specific for this mold. This test is the only commercially-available quantitative test for this mold. Oregon State University is funding a patent application for the method (currently pending). We make no claims about using this test as a diagnosis for HBS. Our lab reports always state that the result needs to be considered by a qualified veterinarian in context with other data. We have seen and reported a significant association between HBS and high levels of A. fumigatus in blood; however, it is critical we all recognize that an association does not necessarily imply causality. The assay is very accurate and sensitive. And yes, A. fumigatus IS ubiquitous but remember, this is a quantitative test.and so the detection of high levels, particularly in places where it should not be (i.e., blood and tissues) is meaningful.
Question 4: The Oregon State people did PCR testing on tissues from seven cases of HBS. They found the presence of A. fumigatus in all seven and C. perfringens in only five of the seven tissues. They make a statement that A. fumigatus has been found to cause disease in immunocompromised humans and a separate statement that the organism can infect the ruminant GI tract and cause hemorrhage.
I have talked to one of the pathologist at our state diagnostic lab about
this subject. His statement was that the diagnostic community was less than enthusiastic about the involvement of A. fumigatus and HBS.
Comment. A. fumigatus is now the leading mycoses in humans. It superceded C. albicans in importance as a nosocomial infective agent recently. Roughly 10% of all nosocomial infections in humans are now fungal and the primary predisposing factor is "immunosuppression". It is not certain whether stress and immunosuppression play a role in ruminant mycoses. The last sentence in the statement (above) implies a lack of confidence in the possibility that A. fumigatus could play a role in HBS. We are open-minded about this issue but we also have to say that there are compelling reasons to consider both A. fumigatus and C. perfringens with this disease. Our recent studies (see OmniGen Research Update Volume 2 #6 or our Publications page) document significant association of A. fumigatus with HBS but non-significant association with C. perfringens Type A.
Hemorrhagic bowel syndrome in Dairy Cattle: Preliminary Results from a Case Control Study
Conflict of interest disclosure: Neil Forsberg is a Professor at Oregon State University who has taken a financial interest in OmniGen Research LLC.
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