**If you intend to train a few sheep to eek out a bit of extra boom, the answer is f**king don't bother.**

As you can see, after 6 minutes, your 100f investment

**nets a STAGGERING 4.5 food profit**(in real terms).

HOWEVER, if you research Selective Breeding for 300 resources, you get that 4.5 food back a WHOLE 54 SECONDS MORE QUICKLY. So after a mere 67 sheep trained, this upgrade pays for itself in no time!

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However, let's be real. No one builds the pen to train livestock. The more interesting question is, how many animals do I need to bring back to my base before it's worth making a pen? I'm not sure what the answer is but I have done some maths to help find out!

**Here's how 'profitable' a livestock pen will be with varying numbers of animals found:**

These numbers take into account the fact that livestock slowly fatten without a pen. (This is another 'opportunity cost')

**So if a livestock pen costs 200w (400vs), to break even, you need to find:**

-5 sheep/goats

-4 llams

-3 cows/yak

But breaking even isn't good enough because this is a 200w investment over approx 6 minutes. The question is then, how much profit makes this worthwhile? 200w could be a trading post which generates aprox 1.2xp/s http://www.rts-sanctuary.com/Age-Of-Empires-3/showtopic=109488. So you can sort of compare it too 432 xp. More if you get stagecoach I suppose. 200w (400vs) + 432 xp. Does that mean you need about ~850f to profit from the livestock? It's hard to know because food & xp aren't all that comparable.

**But it does seem like you'd need:**

-10 sheep/goats

-8 llama

6 cows/yaks

That doesn't sound right though? People have been building pens on fewer animals than that?

I suppose there is also the fact to consider that making a pen is a way to generate a food source in a game where the first player to run out of natural resources usually loses. So perhaps there is some intangible benefit there to consider. Eitherway, I think some more opinions on this would be good.