Donkeys are able to carry 1 sk of cargo. A yoke requires 2. Does this mean a donkey can’t be harnessed to a cart?
p 69
A yoke is for teams of oxen — they are massive pieces of wood and iron.
A donkey would need the harness/traces to pull the cart — which would be equivalent to a pulk, and since the inventory cost for a pulk is 2 belt slots, that leaves the donkey with the equivalent of four pack slots (1sk = 6 slots).
Good to see you on the forums, @porter!
Just a heads up, this is the area for Burning Wheel; Torchbearer is a little lower.
There’s also an official Discord here: Burning Wheel HQ
Thank you for letting me know. Sorry for posting in the wrong area! It has been ages since I’ve played BW, wish I could find a local group!
Thank you for the quick reply and answering my question!
There’s an LFG forum on the Discord. 
Donkeys have a capacity of 2 sk (See Beasts of Burden, Lore Master’s Manual, page 148). A rider counts as 1 sk. It looks like the reference to 1 sk on page 75 is an error. Consider it errata. Aurochs, donkeys, draft horses, mules, oxen and ponies are all draft animals that may be attached to a yoke.