Oxen.
Another unusual means of draught military transport - very usual, in fact, in places like India and South Africa, but not on the Russian Front, as here, where oxen are used to give a bit of impetus to a mud-swamped German vehicle. Best regards, JR.
This is a companion discussion topic for the original entry at https://ww2incolor.com/gallery/german-forces/46934/oxen.