it was a barbaric experiment to conduct and it was very cruel. it was also a rather morbid thing to do. the sheep themselves are only doing what they can to process their grief. sheep do not understand what death is, and they do not know what has happened to the lamb
I read about this in a book by a farmer who I greatly respect because of his humane practices and focus on sustainable living. The reason why a farmer will skin a dead lamb and place the skin on another lamb is because he wants to encourage the sheep to adopt the living lamb. The sheep has lost its lamb and the living lamb is orphaned. By using this practice, the farmer ensures that the lamb will be raised safely with minimal trauma and the sheep will be able to nurse safely.
The example of a sheep nursing a lamb dressed in a dead lamb skin may sound extreme but if it helps to keep the lamb alive then it is not morbid. The scent and touch of the dead lamb may trigger a motherly response that we do not understand. The sheep will follow its instincts.
Animals rely mostly on the sense of smell and scent in life. So if a lamb is to be accepted by another sheep as its mother, then she needs to recognize its scent. This is the most natural way to do this. It only seems morbid to those who don't understand the ways of nature.