I think the aunt and mom thought the calf is beyond recovery. So they started moving away to feed themselves. Except for humans, others view death in an impassive manner. Since they don't have the concept of life after death, I am sure, they don't dread death. Ofcourse, they do have a strong sense of self-preservation. They know when an offspring or another member is beyond recovery. Among humans, I have seen many cases, where the relatives of a long suffering person become impassive after a certain time and await the inevitable.

It would be interesting to know, if the Forest department will and can try to reintroduce the calf with its herd after it recovers.

Cheers,
Sabyasachi