Differences between Trade Animals and normal Animals

What are the differences between say Trade Sheep and Regular Sheep? I'm trading with merchants and I get the option for either Trade "x" or just a Regular "x" with X being an animal type.

I assumed the trade sheep were purely for trade, but it seemed like I couldn't put them back into my trader to trade off and they started reproducing. Do they just act like normal sheep but a different name?


When your pasture is full, instead of the animals being slaughtered they will be turned into a trade item that you can trade with. They produce no other resources.