There are two different melodies frequently paired with the ‘Away in a Manger’ poetry. The version here is the most widely known in the U.S.A., and is attributed to American James R. Murray (though often given the tune name ‘MUELLER’). This version is set in the pipe-friendly key of D-Major, with three-part harmony, chord symbols, and first verse lyrics.
This is one of over 100 carols printed in the collection, On This Day Earth Shall Ring.
An audio sample, featuring Scottish smallpipes (A-chanter). The harmony parts can be heard on the repeat, approximately halfway through the track: