This Guide is basically the script to my Video. So if you are too lazy to read, consider checking that out.
https://youtu.be/oqsDHRe1gtQ


Overview:
6 types of livestock (sheep, cows, lamas, goats, water buffalos, yaks)
All euro and native civ have sheep, except inca.
Inca porto and spain have access to lamas, porto and spain need a card for that though!
Haudeno and the other euro civs can make Cows (India can make cows too, they are called sacred cows but are essentially the same unit)
Japan cant produce livestock
Chinese use Goats and Water buffallos. Water bufallos are essentially cows. Yaks can only be found by scouting or with techs.

How do the different livestock compare to each other?
Sheeps cost 100 food, take 10 seconds to train, have 50 initial food and 300 maximum food. You can build up to 30 sheeps at once. If someone steals your sheep or you send them to your ally (india, japan) you can retrain up to 30 sheep again (even when the sheeps are still alive).
Goats are like sheeps, except they fatten faster at villages.
You can produce 20 of all the "bonus" livestock, so lamas, cows and water buffallos. All have lower cost, have higher maximum food and higher fatten rates. Cows beeing the fattest, while lamas being the cheapest to produce.
Cows profit the most of livestock pens (of the units you can produce). Water bufallos are essentially cows.

Lamas are the cheapest and fatten faster than sheeps, especially on their own (highest fatten rate without pen). Lamas have a lower fatten rate without livestock pen, but you need a livestock pen to train them. This means the lama card is strictly worse than the cow card (you allways have a livestock pen, when you produce lamas, since you can only produce lamas in a livestock pen)
Yaks do have the highest gathering rate at the livestock pen!


How long does it take for your livestock to become fat without livestock pen and with livestock pen? How do Cards/ Upgrades affect this?
up to 30 mins for cows without a pen. Sheeps take 20 minutes without pen to fatten.
With a pen you can reduce the time to under 7 minutes, yaks only need 5 mins to fatten on a unupgraded livestock pen.
The minimum time you can achieve is with the brits, where your sheep and cows take 4 minutes to fatten.
In a Real game Chinese goats fatten the fastest, they need a little over 3 minutes to fatten (fewer cards, but base livestock gather rate is higher than sheep!). No other civ can train goats easily.
Talking about chinese: Chinese have a debuff until Age 4. Until Age 3 they produce 75 % slower, in Age 3 25 % slower and in Age 4 have the livestock pen rate. So goats produced in age 2 take more than 10 minutes to fatten, in age 3 they take a bit more than 5 mins to fatten.

Once they are fat, your villagers still need to gather the food.
Lets take a look at the rates. Without upgrades they gather at a rate of 2 food/s with fulling mills and refrigeration you can lift the rate, so you are gathering faster from your sheep than from crates (up to 8.4). You also have to consider that livestock are animals and decay at a rate of 0.75 food/s once killed. This also affects the value you get out of livestock. That s why you should allways use some villagers to gather a single livestock (4 is the usual amount in lategame). Obviously with more vills you get less decay, but you also get more bumping on your villagers and they also might start killing more sheep at the same time.

So lets Take a look at how much value you'll get when you gather one livestock.
You spend 100 food, then you wait until it s fat (for around 5 min to 10 minutes). Then you use 4 villagers to gather the food. For sheep, they take 38 seconds to gather 300 food (without upgrades). This means in 38 seconds, there will be 28 food decayed. Remember you spent 100 food to procude the sheep. So the net profit for one sheep is only 172 food (food capacity - decay - food cost = 300-28-100 = 172). That changes with fulling mills and refrigeration, because your livestock are getting collected faster and hence there is less decay and more profit. The net profit for different livestock compared: You will get the most value out of cows with fulling mills. This is because cows cost only 80 food and have a food capacity of 500. Sheep and goats are valuewise the worst livestock. Lamas are in between cows and sheeps, but are just worse than cows.


Now lets calcuate the net food gather rate of livestock.
I use the net food profit i calculated earlier and divide that by the time it takes for the livestock to be gathered. Then i divide by the amount of vills. So 172 food / 38 Seconds / 4 Villagers. I compare the naked rates and the rates with cards! This means you get a Net gather rate of 1,15 food / second for sheeps. With Fulling mills that rate goes to over 5,41 food/ second. For comparison: Hunts with steel traps and hunting dogs have a gather rate of 1,1 food / s. Why are the rates so low? Remember: Your villagers need to gather the 100 food invested into sheeps first...this is not "profit gathering". Also you loose some food on decay.

Is it worth it to build a livestock pen and make sheeps?
If you build Lifestock pen, invest 100 food into a sheep, wait 367 Seconds (6 min) until it is fat…Then you can achieve a gather rate of 1,15 food/s with 4 villagers gathering the sheep (If you use less, there is more decay) (compared to hunts 1,1 f/s with upgrades). Conclusion: dont ever build a livestock pen to train sheeps for supremacy! Cows might be a bit better, but are still to weak in my eyes to spend a card on. Again even for cows you need to wait a little bit more than 6 minutes until you can gather them at a rate of 1,5 food/s (valuewise).
Could look deeper into it, but tbh the result is so dissapointing that it is not worth it.
2 Reasons:
Opportunity Costs: Each ressource you spent and which is not giving you an immediate payback is bad. Payback of 367 Seconds: 6 mins of doing absolutely nothing is bad!
Inflating worth of ressources. 100 food at minute 5 is as valuable as for example 150 food at minute 10 (Depending on what you are assuming). Just like in Real life, 100 Dollars 20 years ago has the same buying power as 150 dollar today! Tool in description: Interesting to play around! https://www.inflationtool.com/us-dollar/2000-to-present-value

How many Livestock do you need until building a livestock is a good idea? I ll ask the simple question: IF you build a livestock pen, how much more food do you have 5 minutes after you built the livestock pen, for each cow, lama, yak you found?
For each sheep you ll get 150 additional food, for each lama 225, for each cow 275 and for each yak 300 additional food.


My advice:
Once you have 7 you can allways build one. Lamas, cows and yaks it s worth it after you found 4 to 5.

Summary:
The fact, that the Age 1 Card 7 sheep + 1 livestock is not a auto include (Worth around 1000 ress) and is often not the optimal choice tells you everything you need to know about the state of livestock in supremacy.
Dont make livestock in Supremacy. The investment is just too big for it to be reasonable.
Build Livestock pen if you found more than 5 yaks/cows/lamas build a pen.

What is the maximum achievable total Food per second?
up to 55 food/s with only 9 vills.
What is the gather rate/vill?
around 6 food per second for all civs which have fulling mills
What civs have the best livestocks?
Chinese Cowboom best. Why? Base gather rate of goats and yaks the highest
Note: You need less vills for brits and haueno because the Herdables take longer to fatten. That s why they use less villagers and get fewer total food/s. This also means that the briton faster livestock fattening card gives you +5 food/s in a treaty game!


And how does that compare to mills (Postimp with age 2 and age 3 cards)?
Mills are faster than all livestock gather rates, except those with the fulling mills.

Summary:
Only use Livestock in Treaty when you have Fulling Mills!

India
India xp gather rate for livestock is mostly similar to the normal fatten rate. Sheeps the slowest in all regards, lamas the fasted without Sacred field and Cows the fastest on sacred field. By the way: The Fattened goat is not a goat with 300 food it is a goat you can with china with a card or with the sufi native ally. One thing that triggers me a bit is that the fattened goat has the fastest rate on sacred fields. Completely unintuitive and doesnt make any sense to me, but now you know. Sufi allies are really good for indians apparently and you should send those fattened goats to the sacred field to get allmost 50% more xp than cows (in lategame scenarios). I m also not 100 % sure if xp gather rate + the xp gather rate on sacred field is additive or exclusive. But it should be additive (so auto gather rate + gather rate at sacred field) otherwise there would be a situation, where if you send the ghorashka card lamas and goats would gather faster when not on sacred field.

So in a real game if you managed to get 11 herdables, those are worth like 1 tp. With the gorashka card, you can allmost double the value. Also if you found 10 yaks, your sacred field has allmost the same value as a tp. The upgrade gives 25 % increased xp gather rate on sacred field. That means when you have allready 20 animals on a sacred field, you would get less than 4 additional ones (Since it doesnt affect auto gather rate). That means only get that when you allready have 20 or in treaty
In a nutshell:
Send fattened goats to sacred field. If you dont have them use your sacred cows, yaks or water buffallos.
If your sacred fields are full and you are in a tg treaty. If possible, let them send lamas to you. The second best would be cows, then goats and the weakest are sheep.


For japanese:
Livestock are better than hunts (50% to 100%!). Sheeps are again the weakest, while cows are the best. Lamas and yaks in between. The fattened goat anomaly is not existent for japanese. Yes you can frame that sentence: The fattened goat anomaly is not existent for japanese ;).

Dont make livestock in Supremacy
If you found more than 5 Livestock in Supremacy, build a Livestock pen
In Treaty: Feed your japanese and indian allies with livestock
Civs with fulling mills(Haudeno, Brit and China): Go for Livestock

Patch: December 2020

Age of Empires III: Definitive Edition© Microsoft Corporation. This Video was created under Microsoft's "Game Content Usage Rules" ( https://www.xbox.com/en-US/developers/rules ) using assets from Age of Empires III: Definitive Edition, and it is not endorsed by or affiliated with Microsoft.