HerdSim is a simple and easy to use animal roaming simulator.
Simply drag the prefab to the stage and it will move within the roaming area. Instead of RigidBodies this system uses rays to avoid and push away from obstacles. This method is a lot friendlier to CPU usage and allows for a lot more instances.

Drag & Drop roaming animal system
No rigidbodies used – very CPU friendly
Gizmos that shows roaming areas and herds
Simple UV map, easy to change texture
Easily use custom models (legacy animations)
Works very well on mobile
Includes mobile prefabs and materials

Includes 5 Models

1216 and 598 tris cow model
2048x2048px texture/bump resolution
568 and 294 tris animated rat model
1024x1024px texture/bump resolution
606 tris animated chicken model
1024x1024px texture/bump resolution
320 tris animated piggy model
2048x2048px texture/bump resolution
640 tris animated sheepmodel
2048x2048px texture/bump resolution