The letter in-toto:  Letter to the Food Safety Inspection Service of the USDA regarding Mad Cow Disease  (Thu Mar 01 2001)
It's a long and fairly technical letter by CU's Michael K. Hansen, Ph.D to the USDA's Administrator of  FSIS..
The following is my stab at a concise summary- hopefully all extracts from the letter are in quotes.  I've marked stuff that interests me in bold.

"We would like to discuss the steps USDA is taking to prevent mad cow disease and related transmissible spongiform encephalopathies (TSEs) in the United States. We believe that USDA's efforts related to swine and cattle need to be restructured and expanded in significant ways to assure meat safety. The following represents our views on the kind of research and monitoring that is needed."

The following follows the basic outline of the letter

Swine

• Requests that a '79 study of pigs with a CNS illness  at a packing plant be reopened to determine if TSE was the cause.  Said one pig in the study had visible spongiform damage of  brain and cited a scientist as saying it suggested a TSE.  Other pigs were noted as having similar motive symptoms.
• Requests more pre-mortem studies- i.e. look at packing plants for pigs having symptoms of pig in '79 study and have inspectors observe pig at  plants while they are in motion.
• Repeat another previous study and survey of older pigs and those with  neurological symptoms.
• "Finally, USDA should ensure that a proper feeding experiment be done to see if pigs can get BSE through the oral route. Experiments in the United Kingdom have shown that pigs are susceptible to BSE. Pigs inoculated via intracranial, intravenous and intraperitoneal routes with BSE develop a TSE (Dawson et al., 1990). A feeding experiment is currently underway in the UK to see if BSE can be orally transmitted to pigs; as of March, 1997, some 6.5+ years after the start of the experiment, none of the pigs fed BSE brain have come down with a TSE.  Unfortunately, the design of this experiment severely limits what we will learn from it...the pigs were not fed BSE brain continuously."
• "....there are two epidemiological studies that have linked the consumption of pork to a human TSE, Creutzfeldt-Jakob disease (CJD). Both studies are discussed in our comments to FDA on their proposed draft feeding rule (copy included) so we will only summarize them here."   1/3 of the striken had eaten brains   "... there was evidence of dosage dependency with the pork products, i.e.the more you ate the greater the risk of contracting CJD"
• "....a number of studies suggest that CJD may be misdiagnosed as Alzheimer's disease or other senile dementia and that a small percentage of the Alzheimer's cases are actually CJD."    Details:
• A study at the University of Pittsburgh, in which autopsies were done on 54 demented patients diagnosed as having probable or possible Alzheimer's or some other dementia (but not CJD), found 3 cases (or 5.5%) of CJD among the 54 studied (Boller et al., 1989).
• A Yale study found that of 46 patients diagnosed with Alzheimer's , 6 (or 13%) were CJD at autopsy (Manuelidis and Manuelidis, 1989).  Since there are over two million cases of Alzheimer's disease currently in the United States, if even a small percentage of them turned out to be CJD, there could be a hidden CJD epidemic.

• "CU believes that USDA's BSE Surveillance program is flawed in both design and execution. The program is based on the assumption that a native bovine TSE does not exist in the US and that the major threat comes from a British-style BSE. A good deal of indirect evidence, involving studies on transmissible mink encephalopathy as well as on scrapie transmitted to cattle, suggests that a native bovine TSE occurs in the US and may be hiding among the "downer cow" population.
• Discusses Transmissible mink encephalopathy (TME)    Suggests that TME may result from consumption of "downer cows." Cites a '63 simultaneous TME outbreak on 2 farms and states:
"Suspecting a possible feed-based source of contamination, based on the 1961 outbreak, the scientists went through the two farms' feed records. A striking finding was that, from July through October 1962, meat "from beef carcasses unfit for human consumption (so-called 'downer' cows)" that came from Farm A was fed to minks on both Farms A and B. As the scientists noted, "Since mink on both farms developed the disease almost simultaneously, we believe this feed component has to be incriminated" (Hartsough and Burger, 1966a: 389)"
Also cites a study in '85 of another TME outbreak which, "produced a number of lines of evidence that linked "downer" cows to TME".  Also notes an experiment which injected TME infected mink brain material into calves - within they had "...a fatal spongiform encephalopathy. They did not act like "mad cows" in Britain; rather they just got a bit lethargic and fell over, i.e. they exhibited symptoms of "downer cow."
Scrapie-infested cattle studies  Describes a '79  study which inoculated cattle with scrapie to see if cattle were susceptible to it.  10 cows were injected with scrapie-infested brain homogenates and feed it.  After 2-4 years, 3 cows had the appearance of downer cattle and did not have the symptoms of BSE.  Their brains did not appear spongy and c diagonse of scrapie could not be confirmed.  In '90, after a new test for the suspected agent responsible for scrapie, came out, remains of the brains  tested as positive.  The scientist concluded that the evidence suggested that a bovine TSE was present at a low level in US cattle and that "downer cows" should be tested:

• "In sum, the indirect evidence from the TME studies, as well as from the scrapie-inoculated cattle studies, points to the existence of a native bovine TSE in downer cows in the U.S. This native BSE could arise spontaneously in cattle; it seems unlikely that all cases are linked to scrapie"......"By 1990, even NIH (in the person of Dr. Clarence Gibbs) was calling for testing of downer cows for the presence of the mutant prion using an immunohistochemical probe"   .....  "The same year, USDA set up an advisory committee called the Scrapie/BSE consultants committee."  .... "This committee designed and began the BSE monitoring program done by the USDA"
• At first, the monitoring program did not look at the brains of downer cattle athough one committee member requested it do so.  The member requested also USDA funds to examine downer cattle and was turned down.  Downers were first included in the program in '96.  "As of January 23, 1997, some 5,342 cattle brains had been tested. Yet only a couple hundred of the brains came from downer cows".
• Recommends the USDA look for not only BSE, but for a native bovine TSE which is different in physical cattle symptoms and in brain appearance. Specifically, it recommends use of a cited immunohistochemical probe..  Also recommended focusing on The USDA could also focus, " ....on states which make the largest use of rendered ruminant protein in their cattle feed and that have some of the oldest cows. This would mean focusing on the larger dairy states such as Wisconsin, California and New York.