It appears to be from a gov website. http://www.usda.gov/ That would make it authentic IMO.
We need to figure out if this is real or just a threat.
I saw this October 1, 2013 memo from Audrey Rowe
http://www.usda.gov/wps/portal/usda/usdahome?contentidonly=true&contentid=shutdown_procedures.html
but not the OP’s October 11, 2013 memo on the USDA website.