18 May, 11:09
IRFU Chief Executive Philip Browne has issued a statement following confirmation of Ronan O'Gara's decision to retire from playing professional rugby.
Prop John Afoa is part of Mark Anscombe's 25-man panel following a short stint in New Zealand. Half-backs Michael Heaney and Paddy Jackson have also been added to the squad.
Ulster remain top of the RaboDirect PRO12 table despite the 16-12 home loss to the Ospreys last weekend. They have a seven-point advantage over second-placed Glasgow Warriors head into the round 15 matches.
ULSTER Squad (v Zebre) - Backs (11): Ruan Pienaar, Michael Heaney, Stuart Olding, Paddy Jackson, Paddy Wallace, Luke Marshall, Darren Cave, Michael Allen, Andrew Trimble, Chris Cochrane, Ricky Andrew.
Forwards (14): Rob Herring, Niall Annett, Tom Court, Callum Black, John Afoa, Declan Fitzpatrick, Johann Muller, Neil McComb, Lewis Stevenson, Dan Tuohy, Chris Henry, Iain Henderson, Mike McComish, Robbie Diack.