I have used a temporary file to do this in the past, like this below.
DIR /B *.DAT | FIND.EXE /C /V "" > COUNT.TXT
FOR /F "tokens=1" %%f IN (COUNT.TXT) DO (
IF NOT %%f==6 SET _MSG=File count is %%f, and 6 were expected. & DEL COUNT.TXT & ECHO #### ERROR - FILE COUNT WAS %%f AND 6 WERE EXPECTED. #### >> %_LOGFILE% & GOTO SENDMAIL
)