Cloning is the production of an exact copy of a cell, any other living part, or a complete organism. Cloning of an animal was successfully performed for the first time by lan Wilmut and his colleagues at the Roslin Institute in Edinburgh, Scotland.

They successfully cloned a sheep named Dolly (see figure-c below) Dolly was born on 5th July 1996 and was the first mammal to be cloned. During the process of cloning Dolly, a cell was collected from the mammary gland of a female Finn Dorset Sheep Simultaneously, an egg was obtained from Scottish blackface ewe. The nucleus was removed from the egg. Then, the nucleus of the mammary gland cell from the Finn Dorset sheep was inserted into the egg of the Scottish black face ewe whose nucleus had been removed. 

The egg thus produced was implanted into the Scottish black face ewe. Development of this egg followed normally and finally Dolly was born. Though Dolly was given birth by the Scottish black face ewe, it was found to be absolutely identical to the Finn Dorset sheep from which the nucleus was taken. Since the nucleus from the egg of the Scottish black face ewe was removed, Dolly did not show any character of the Scottish black face ewe. Dolly was a healthy clone of the Finn Dorset sheep and produced several off springs of her own through normal sexual means.

Unfortunately, Dolly died on 14th February, 2003 due to certain lung disease. After claims of Dolly, several attempts were made to produce cloned mammals However, many died before the birth or die soon after the birth. The cloned animals are many-a-time found to be born with several abnormalities.