Get your knees muddy!
Infact get right down on the ground!

Most people shoot animals at the zoo and on farms from standing - which though pleasing is a common position that hte human eye views those animals from - now getting down lower and shooting from and angle looking directly at or up at an animal makes for a far more interesting angle as most people don't see from that perspective.
Course you might want to wear a set of waterproof trousers and possibly a top (they wash well and don't stain) and watch out for large roundish blobs of mud - they ain't mud!