Update ->

Using Biomes O Plenty 3.0.0.1631 - 1.8.9 and Forge 11.15.0.1696 - 1.8.9 | Tested with straight Biomes O Plenty.

This was a server and client test environment.

(Check spawn code maybe? Perhaps LexManos did something to the id table controlling spawns and additional biomes?)

Do you mean BoP entities or something? I've teleported around to quite a few biomes on that version of Forge and BoP and have seen pigs, sheep, chickens, cows, skeletons & spiders (under a tree in the dense forest) in both our biomes and Vanilla.I'm not sure if you're just really having bad luck or something else...

I will look into it further.