"L'aze d'alegre" is not clear what it means, but the "d '" is thought to be euphonic so the meaning would be "l'aze alegre" (the cheerful donkey).
The song was collected in Sambuco (Piedmont), but the song seems likely to come from Occitania.
We still remember the testaments of the donkey, as of other domestic animals, which date back to medieval times. They had a ritual meaning: the partition of the body, which continues to exist thanks to the donation of vital organs to those who can still use it.