As I noticed on my DokuWiki-installation, DokuWiki removes everything after a </code> up to the end of the line from the page-content in the feed. I am not quite sure if it is correct that I have the <code></code> with additional content before, in and after the tags together in one line, but at least in the normal view it works.
Example:
http://www.content-space.de/dokuwiki/projekte/dokufs /
http://www.content-space.de/dokuwiki/feed/content (at the moment second item from top).