This is some info I have found on German Horse drawn vehicles some WW I and some WW II:
The site the Axis History Forum has a section Ron Klage's panzers and other vehicles section. There is a post on German horse drawn transport mostly WW II but some WW I and between the wars. lets just say the German army used of different horse drawn vehicles. There is also a post on filed kitchens most WW II some WWI.
Airfix magazine Sept 1969 there is an article on German army horse drawn transport 1939-1945 by W.J.K.Davies
In the Oct 1968 issue there is an article "The German Army 1914-1918" David Wash that deals with transport ect.
there is a modeler Dave Cot that is putting some of the old Airfix articles online see:
www.cavecot.net/modlling/reference/airfixmagazine
There is also the book:
The German Infantry carts, Army Filed Wagons, Army Sled 1900-1945 Wilfred Kopenhagen
Note I have read towards the end of WW I the german army was so short of horses that they had to use oxen even cattle to haul their artillery pieces ect around. Also with many WW I armies fresh meat was often herds of cattle and other livestock.
