The carol originated in Sicily in approximately the seventeenth century, and is traditionally played on the zampogna (a type of large, sweet-toned bagpipe with two drones and two chanters) by shepherds who come to the villages throughout Italy. The shepherds would serenade private homes and statues of the Virgin Mary in the nine days before Christmas.

It is believed that Handel adopted pipe music with his so-called `Pipers Carol' or `Canzone d'l Zampognari' which he used for "He Shall Feed His Flock Like a Shepherd" in "Messiah." He may have heard this melody during a visit to Naples in 1708, 33 years before composition of the oratorio.

From http://www.hymnsandcarolsofchristmas.com/Hymns_and_Carols/NonEnglish/canzone_dl_zampognari.htm