The influential flanker has been ruled out of the rest of the tournament with a shoulder injury.
Leavy is replaced in the side by Buccaneers clubman Rory Moloney and Sean O'Brien takes over the captaincy role.
There are two changes on the bench with Stephen Gardiner replacing Joe Joyce and Frankie Taggart moving to the bench in place of Michael Triggs.
Jack O'Donoghue has completed his return to play protocols and is declared fit to reclaim the number 8 jersey.
Ahead of Ireland's third home game of the campaign, Ruddock commented: "The end result against England did not reflect the effort and endeavour shown by this Irish side at Franklin's Garden.
"We must take our chances when they come along and although we did well to draw with Italy last year we would be confident that at Dubarry Park we can get the desired result."
Match tickets can be purchased in advance at Buccaneers RFC and/or the Bounty and can also be bought at the turnstiles on match nights.
Stand seats generally sell out in advance of each match. Ticket prices are as follows: Stand €20, Terrace €15, Students/OAP €10 and Family (two adults and two children to ground) €30.
Group discounts are available to clubs/schools, etc. Contact Buccaneers administrator Geraldine 0861732711 (during office hours) or email firstname.lastname@example.org.
IRELAND UNDER-20 Team & Replacements (v Italy Under-20s, 2014 RBS Under-20 6 Nations Championship, Dubarry Park, Friday, March 7, kick-off 7.05pm):
15. David Busby (Queen's University/Ulster)
14. Cian Kelleher (Lansdowne/Leinster)
13. Dan Goggin (Young Munster/Munster)
12. Peter Robb (Old Belvedere/Leinster)
11. Adam Byrne (UCD/Leinster)
10. Ross Byrne (UCD/Leinster)
9. Nick McCarthy (UCD/Leinster)
1. Peter Dooley (Lansdowne/Leinster)
2. Max Abbott (Cork Constitution/Munster)
3. Rory Burke (Cork Constitution/Munster)
4. Sean O'Brien (Galwegians/Connacht) (capt)
5. Ross Molony (UCD/Leinster)
6. Peadar Timmins (UCD/Leinster)
7. Rory Moloney (Buccaneers/Connacht)
8. Jack O'Donoghue (UL Bohemians/Munster)
16. Sean McNulty (UCD/Munster)
17. Denis Coulson (Lansdowne/Leinster)
18. Oisin Heffernan (Lansdowne/Leinster)
19. Stephen Gardiner (Lansdowne/Leinster)
20. Frankie Taggart (Belfast Harlequins/Ulster)
21. Jack Cullen (Bruff/Munster)
22. Conor McKeon (Lansdowne/Leinster)
23. Harrison Brewer (Terenure College/Leinster)
IRELAND'S RBS UNDER-20 6 NATIONS FIXTURES/RESULTS:
IRELAND Under-20s 34 Scotland Under-20s 7
Friday, January 31
IRELAND Under-20s 16 Wales Under-20s 0
Friday, February 7
England Under-20s 33 IRELAND Under-20s 9
Franklin's Gardens, Northampton
Saturday, February 22
IRELAND Under-20s v Italy Under-20s
Dubarry Park, 7.05pm
Friday, March 7
France Under-20s v IRELAND Under-20s
Stade Maurice Trélut, Tarbes, 8.55pm local time/7.55pm Irish time
Friday, March 14