From the National Museum Wales’ website:

“For centuries some kind of musical calls have been used to urge oxen at work. Many examples have been preserved of the stanzas (together with call appended) formerly sung to oxen ploughing teams in the southern half of Wales – it was there, and in Glamorgan specifically, that oxen were last retained for ploughing Welsh soil (until around 1880). The texts of most of the oxen songs chronicled in Glamorgan are in the free metre known as triban. A large number of these are love or triad stanzas, and the finest among them display rare terseness and wit. The majority are self–contained units but ox–drivers at work would naturally sing several together in a series.”

https://museum.wales/collections/folksongs/?id=1