There are three possibilities:.
1. Although, some people thought it was the love song about girl named Donna, the song is obviously about the calf about to be slaughtered.
2. Of course, there could be some hidden meanings... maybe it’s a metaphor. Calf could be a virgin about to be "slaughtered" in bed by a big bad male wolf. But I don’t think so.
3. In the third strophe: "Calves are easily bound and slaughtered. Never knowing the reason why." since he mentions calves, it could be a reference to young soldiers. Once again I don’t think so. I think this is just an anti-meat-eating song.