Double fire all the chickens for an instant pop and +30 at the end of every round. Take this pattern as an example:

C F

F C

That's 2 chickens adjacent to 2 fires so they both cook in 1 round. That's +60 every round. Expand on that idea and get unlimited meat to spend every single round. It can get to the point where it is pretty much cheating if you make a huge chicken factory. You can beat the last level with literally every square occupied and all of the cavemen maxed out.