I would like to know if it would be possible to obtain a recent version in text format (word, OpenOffice, ...) of the thesaurus in French only.
I'm sorry but we don't have a recent version in text format. Here is a link to SQL scripts with the terms in all languages. The only table you really need is "agrovocterm". From there you could generate a text version in french quite easily by filtering on the languagecode. http://agrovoc-cs-workbench.googlecode.com/files/agrovoc_20120710_115715.zip