Mule Cloning

Eleanor Roberts-Caudle


Biology MT 5 Level four





Mule Cloning

Cloning is a quickly developing field in science. It has opened many doors which had been previously thought to never open. Horses, Rats, dogs, camels, ferrets, and other normally reproducing animals have been cloned. However no hybrids or unfertile breeds had ever been cloned until the mule. Mules are hybrids, and are a cross between a horse and donkey, which are unfortunately unfertile. Unlike a horse or donkey, they cannot give birth to their own due to the amount of chromosomes. Horses have 46 and donkeys have 62, resulting in the offspring of their breeding (mule) having a total of 63 chromosomes, 32 come from the stallion/ mare, and 31 come from the donkey/ jack. This odd number of chromosomes prevents them from producing offspring.

Mules have been becoming a steadily more popular animal to breed, and mule racing is one of the recent sports that have started in California. Regrettably the fact that they are infertile inhibits the ability to single out a well-bred mule and try to develop a better bloodline, as has been done with other animals. Cloning represents a unique opportunity to mule enthusiasts; it would enable mule breeders to expand their attempts to create a bloodline of good mules. The first cloned mule, Idaho Gem and the other identical mule clones have been a success. They were created using the cells from the mule fetus of the sire and dam that produced the champion mule racer Taz.

This is done by taking the cell of the given animal, in this case the cell from a mule fetus that was created in 1998 with the sire and dam of Taz. They then transplanted the cell into the egg of a horse that’s nucleus had been removed. The egg was then fused with the mule cell using electricity, and then stimulated with calcium which activated the egg causing it to divide as an egg would if fertilized as in reproduction. Scientists had had difficulties cloning equines and the scientists doing the mule cloning had deducted that if they increased the levels of calcium it would increase the cells growth; this was shown to be correct. The egg was then cultured until an early stage embryo formed. The mule egg would have then been transferred into a mare.

Only 21 pregnancies in the mares were successful, and three of them were carried to term, Idaho Gem, Utah Pioneer, and Idaho Star. Some have shown concern that the mules may age more rapidly than normal, as they believe Dolly the sheep might have. However the fetuses did not show any abnormalities, and so far the cloned mules have displayed only a healthy vigor in the racing world.