First of all make sure that you pass material number with leading '0' in your select statement.i.e.
git_output-matnr should contain material number with leading '0's.
SELECT datuv
atinn
FROM ausp
INTO TABLE it_ausp FOR ALL ENTRIES IN git_output
WHERE objek = git_output-matnr.
Also, when you loop through it_ausp instead of using APPEND use MODIFY statement to modify it_ausp or append another internal table say it_ausp1 instead of it_ausp. Regards