He was also ordered to pay £500 prosecution costs.
At an earlier hearing, the court heard how Byrne had been involved in what was described as a "long running and at times very ugly domestic dispute" with his former girlfriend.
He admitted assaulting her on several occasions between August and December 2002. The judge said he gave Byrne credit for his guilty plea but told him that because he was a trained and skilled boxer, he was capable of "dangerous behaviour".
He said this was especially relevant "when lacking discipline through drug abuse".
The judge added that part of his community rehabilitation programme would involve attending courses in anger management and drug avoidance. Byrne, who was undefeated as a pro, was once convicted of breaking his best-man's jaw.
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