With four contracted second rows unavailable, Academy player James Simpson has been drafted in and could win his second cap for the province.
The 22-year-old made his senior debut 11 months ago in the league derby defeat to Leinster at the RDS. Back rower Robbie Diack will also be considered as an option at lock.
In the backs Ricky Andrew, who made his debut in the win over Edinburgh at the start of the month, will also be hoping to make his second senior appearance for the Ulstermen.
Scrum half Blane McIlroy has been added to the panel with Ruan Pienaar still on duty with the Springboks and Paul Marshall set to play for the Ireland XV against Fiji.
Adam D'Arcy, who covers the back-three, could make his first appearance of the season for Ulster if he is selected in Sunday's matchday squad.
Ulster will have designs on continuing their unbeaten start to the season but will face the difficult task of playing Zebre and Benetton Treviso away over consecutive weekends.
While Zebre are still searching for their first ever competitive victory, they have looked strong at home and have caused problems for numerous teams.
ULSTER Squad (v Zebre) - Backs (11): Michael Heaney, Blane McIlroy, Niall O'Connor, Stuart Olding, Paddy Wallace, Jared Payne, Michael Allen, Chris Cochrane, Ricky Andrew, Peter Nelson, Adam D'Arcy.
Forwards (14): Rob Herring, Niall Annett, Nigel Brady, Callum Black, Ricky Lutton, Adam Macklin, John Afoa, Neil McComb, James Simpson, Robbie Diack, Mike McComish, Ali Birch, Roger Wilson, Nick Williams.