Beasts of burden (4)

'beasts of burden' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for yaks that I've seen before include "Wild oxen of Tibet" , "Rabbits" , "animals" , "Tibetan oxen" .)
'beasts of burden' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for oxen that I've seen before include "(E.g. draught) cattle" , "Bovine animals, in yoke" , "Beasts of burden or domestic cattle" , "Horned farm animals" , "Domesticated cattle" .)
'beasts of burden' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for llamas that I've seen before include "Sal and Mal for the animals" , "Camel-like animals" , "domesticated guanacos" , "South American pack animals" , "S American animals related to the camel" .)
'beasts of burden' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for asses that I've seen before include "Hardy and sure-footed animals" , "Small, sure-footed animals" , "Jennets" , "Animals of horse family" , "Braying animals" .)
'beasts of burden' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for donkeys that I've seen before include "Braying creatures" , "stupid people" , "Beasts of burden" , "Asses" , "Long-eared creatures" .)