With one eye on Thursday's match against Wigan Warriors, Paul Anderson rested many of his stars and paid the price as the Bulls ran riot.
The result sees Francis Cummins's men draw level on points with ninth-placed Widnes Vikings in the Super League standings.
The 23-year-old scored a try in the 34th minute but for the first time in the match he missed the kick, which meant that the home side led 34-0 at half time.
Sammut slid over for the second time in the 42nd minute before completing his hat-trick on the hour mark.
The Australian scored his fourth to make it 46-6 and Elliot Kear increased the advantage in the 74th minute.
Lulia, on his final appearance for the Giants, brought up his hat-trick just before the buzzer, allowing Foster to complete the rout.