Michael Laverty kisses the Enkalon Trophy

Marshall Neill, Bruce Anstey, Gary Johnson and Michael Pearson completed the top six while Toomebridge's Laverty also won both Irish Superbike rounds.

Ian Lowry was a double Supersport 600cc winner and William Dunlop and Ryan Farquhar both took a 250cc victory.

Nigel Percy won both 125cc races and Alan Glasgow both Minitwins events.

Scobie Killough was a double sidecar winner at the windswept County Down circuit on Saturday.

In the first Irish Superbike race of the day, Laverty was a start-to-finish winner with Neill seeing off Donald in a thrilling battle for second place, then Pearson, Brian McCormack and Alistair Seeley completing the top six.

Laverty again came home ahead of Neill and Donald in Superbike race two, with Pearson, Johnson and Denver Robb following close behind.

British championship hopeful Lowry won the first Supersport race by nine seconds from Donald, Keith Amor was third, Marty Nutt fourth, Dunlop fifth and Derek Shiels sixth.

Race two saw Lowry beat Amor with Anstey completing the podium and Nutt, Donald and Dunlop the next finishers.

Dunlop beat road race rival Farquhar in the first 250cc race but Farquhar took the honours from Paul Robinson in race two.

Percy, Robinson and Mark Lunney was the finishing order in both 125cc races.

The action continues at Kirkistown on Easter Monday, with another full programme of races.