So your company has a mentoring program. but you are a line manager and really don't want to lose production time while your employee is off taking a "break." Right?
You will see that in the long run, a company-wide mentoring program will only help to increase production as well as the company's bottom line. In the short term, it may seem like an inconvenience to be short-staffed, but your employees' professional development and devotion/loyalty to the company will increase as a result of a corporate wide mentoring program.