Ood Operations (AKA the "Double O") was a human run corporation during the Second Great and Bountiful Human Empire that sold Ood servants. It bred and processed Ood centrally at a large facility on the Ood Sphere and shipped them to Ood distribution centres throughout the three galaxies, from which they were sold into slavery. At some point it was said every human had an Ood servant. They filled all kinds of functions, from household to pilot, from personal trainer to military models.
The company had made the Ood subservient by removing their secondary external brains and by placing a circle of energy pylons around the Ood Hive mind, This acted as a telepathic inhibitor. Halpen's personal Ood, Sigma, had been dosing Halpen with a solution mixed with hair tonic that transformed him into an Ood.
The Tenth Doctor and Donna shut down the telepathic inhibitor and restored the Ood's ability to "sing" telepathically again. The Ood song called out for all Ood off-planet to return home. With the Ood free and most of the company's staff dead or fleeing from the Galactic Police, Ood Operations was shut down and the base was abandoned, allowing the Ood to be free and live naturally again. (TV: Planet of the Ood)