Is it permissible to offer as a sacrifice a ram with a docked tail, of the type of rams imported from Australia that have short tails?

Australian sheep do not have docked tails; rather, they are created with small tails, and their sacrifice is valid if they meet the conditions and are free from defects.

As for sheep that are naturally without a tail or a rump, their sacrifice is valid. However, if a sheep's tail is amputated, its sacrifice is not valid, whether a little or a lot was cut off. This is the preferred view among jurists and the doctrine of the Shafi'is.