Orr is reported to be interesting Bradford City and Burnley, while Zola-Makongo is a target for Sheffield Wednesday, Bradford City and Swindon Town.
Neither player is likely to feature in the United first team in the near future and Sir Bobby believes that a spell of first team action elsewhere could be good for their development.
"There are clubs interested in those two - several are interested in Zola," he said.
"But we have not yet heard back from the clubs that expressed an interest. I would be happy to let them go out on loan - it would be good experience for them.”
Sir Bobby has already let Gary Caldwell, Brian Kerr and Diego Gavilan leave on loan, while Michael Chopra and Steve Caldwell have benefited from similar moves in the past.