I was hoping someone else would answer.
From what I've heard (so no personal experience yet), from about the 5-6 yr mark they decrease in eggs laid per clutch, but they don't stop.
From that, I'd imagine then that there's no age barrier, as they or the partner either wouldn't be interested, or the eggs wouldn't be fertile.
How old is the one you're thinking of breeding, if that's the Q.?
Hope someone else can help a bit more - Kathy