There is a folk song from the 19th century, about someone who curses the town's butcher because he chopped down the legs of a calf. The song is very sad, the singer expresses his sorrow for the poor little calf, because without legs it can no longer walk, so he must carry it on his back.
However, in reality, the singer is sad because of something else. What is it?
Note: the song itself really exists, but is not well known, and it's not in a world language, so probably very few reading this riddle had the occasion of ever hearing it. However, it's perfectly possible to answer this question without having heard it.
What might make him force to carry something on his back most of the time, and what does it have to do with a calf or a cow? Remember, it's the 19th century.