Fetching Site users Details to use it under Defect module

Hi All,

       I need to know how to get value from Domain Authentication field and use it to populate user defined value in Defect Module.

This value is found under Site Admin -> Site Users as show in image below.

From the below image i need the "OU=" value and store it in a user defined field.

Is this value coming from any System field or do we need to get this is from Database?

Thanks in Advance