The vessel unloaded its milestone sheep in Doha, Qatar, last night, and is now returning to Perth to load another consignment for the Middle East.

The sheep milestone comes only two months after the vessel's 500,000th cattle milestone was achieved.

The MV Becrux entered the Siba Ships livestock fleet in 2002 and has completed 77 voyages since its launch.

Its speed and animal welfare advances have cemented its position as the flagship of the world’s livestock fleet.

"With its superior feed, water and ventilation systems, the MV Becrux has been a resounding success for Siba Ships and Australian sheep and cattle producers," Siba Ships chairman Mauro Balzarini said.

"It was that success which prompted Siba and Wellard to place our recently announced $US250 million order for two new sister vessels to the Becrux."

The bulk of the cattle and sheep on the MV Becrux's voyages have been supplied by Australia's largest livestock exporter, Wellard Rural Exports, which enjoys priority access to the MV Becrux.

"The Becrux doesn't just exceed the industry standard in terms of voyage success rates, the sheep and cattle on-board the Becrux arrive at their destination in better condition than aboard any other vessel," Wellard Rural Exports managing director Steve Meerwald said.

"That ability enables Australian producers to retain their competitive advantage in the global live export trade."