The weight of this part of a sheep's anatomy (for example, the sheep of the Hissar breed) may be up to 60 kg (130 lb).
Wikipedia also adds:
When being rendered, kurdyuk emits a strong odour, described as "acidy-poisonous". However, it has a rich flavor when ready to eat.
Update: This fantastic post on fat tailed sheep:
https://bogleech.tumblr.com/post/767264269961166848/arsanatomica-arsanatomica-dreamingdeeper