check freesound out http://www.freesound.org/
theres looooooads of stuff on there, all free to use, and theres definitely animal samples, i got loads of bird call samples off of there, you can literally find anything
I actually went to Dudley Zoo in saturday, and I'm tempted to sort some granular samples out using sea lion sounds etc. hah
Also, have you tried checking out nature sounds for film makers? I accidentally ended up with a CD full of cow sounds once - could be worth a look.