Leo Cullen was happy to see his younger players contribute in their Guinness Pro14 inter-pro derby victory against Ulster at the RDS.

But the Leinster coach admitted some frustration at the way things finished on the southside of Dublin city on Friday evening.

The hosts burst out of the blocks, and had their four-try bonus point secured inside thirty minutes.

They would score another four by the hour mark, but then switched off, and Ulster took full advantage to earn a try-scoring bonus point of their own.

"There were lots of good bits, particularly in the first-half," Cullen told Eir Sport afterwards.

"Credit to the players, I thought they applied themselves really well. The second-half was very disjointed.

"There were a lot of tries for both sides. We gave away a lot of penalties, which meant we gave away a lot of good field position, as well.

"Delighted to get a win and a bonus point, (but) frustrated to concede as many points, especially here at home."

The opening 50 minutes for Leinster was very impressive stuff, particularly a try for Rónan Kelleher after some quick thinking by Fergus McFadden from a penalty.

Tommy O'Brien and Roman Salanoa made their senior debuts for the province on the night, and Cullen pointed to the lack of experience of some his players as part of the reason for the disappointing ending.

"There's a lot of young guys coming in there, and a good few guys making their Leinster debuts as well," the Leinster coach explained.

"We'll have a look back. There were some lapses in concentration, perhaps, when we pushed-on on the scoreboard.

"We would like to set a better standard than that.

"Ulster managed to get a bonus point out of the game, and we had them dead and buried, it looked like, at one stage.

"Credit to them for coming back into the game, they stayed in the fight, but was it off the back of our errors a few times?"

McFarland's inexperienced side were overawed for 50 minutes

Ulster had made 14 changes from the side which beat Harlequins last weekend in the Champions Cup.

Four players - Jack Regan, Azur Allison, Stewart Moore and Ethan McIlroy - made their senior debuts for the province, and head coach Dan McFarland was eager to point out the positives afterwards, despite the defeat.

"Leinster rather tortured us in the first-half when they had the ball - they were exceptional, " he said.

"I was proud with our lads. I thought they worked really hard. When you're playing against a team who can play with that tempo, it's really difficult.

"They made us pay in the first-half. We came back and scored six tries.

"There are not many teams who come here, and do that."