I've made a minor tweak now that should take effect next restart. Basically increasing the likelihood of the food animals spawning to 150% current value and reducing the likelihood of a few of the other creatures by about 50%. I have also tweaked creeper spawns down very slightly - by about 20%.
So in this version of the server, if someone kills all the food animals around spawn like on the last server. The food animals can respawn by themself, without admin intervention?