It means that Zebre finish above their Italian rivals Benetton Treviso and qualify for the European Champions Cup.
Zebre quickly put the previous week's 70-10 loss to Glasgow Warriors behind them with Andrea Lovotti and Kayle van Zyl both scoring tries in the first half.
And Carlo Canna added two penalties just before half-time to leave Dragons with a mountain to climb.
Rynard Landman put the Dragons back in contention with a second-half score but Leonardo Sarto, Bruno Postiglioni and Kelly Haimona all ran in scores for the Italians.
Landman and Hallam Amos did grab further scores late on, but it was Bortolami's day as he waved farewell to Zebre with an emphatic win.
"I will have another challenge in the world of rugby as a coach, I feel this new profession is my passion," said the veteran lock.
"I thought a lot of other roads to take; rugby gives me strength and I want to remain by the side of these players and serve them with my experience.
"I am very calm, it was the right time to move on to accept even bigger challenges.
"Being a father has helped me understand what to do in the future: to teach and support.
"I have learned a lot and I have to thank everyone. I have always done everything with the utmost desire to improve and with determination.
"I have to thank Zebre, coach (Gianluca) Guidi and all the coaching staff for giving me the opportunity to captain the team."
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