Mule and hinny – can you tell them apart?

A mule, at left, and a hinny, at right.

Originally published on horsetalk.co.nz on 28 October 2016

A new technique to identify mules and hinnies through mitochondrial DNA has been developed by researchers in Brazil.

It is difficult to separate mules (male donkey x female horse) and hinnies (male horse x female donkey) by appearance alone. The differences between them are subtle and not sufficient to confidently differentiate one hybrid from the other. For example, the head of a hinny is said to resemble that of a horse more than it does a mule, with shorter ears, and more horse-like manes and tails than mules.

Due to their hybrid vigor, the mule and hinny have been used worldwide for carrying loads and people, and for tilling the land from the ancient civilizations of Egypt, Mesopotamia, China, and the Roman Empire. Mules and hinnies are widely used in the management of cattle in large beef cattle ranches in Brazil, which are important to the regional economy.

As soon as horse and donkey species were domesticated, they were crossbred, producing humanity’s first documented attempt at animal genome manipulation.

The distinction between these two hybrids is pivotal for equid breeders, ranchers, and associations that keep the official pedigree of the animals.

The new technique involves looking for mitochondrial DNA (mtDNA), which is inherited from the mother.

In a report published in Genetics and Molecular Research, Mauricio M Franco and others describe a multiplex-polymerase chain reaction method, which targets the hyper-variable mitochondrial DNA D-loop region.

“Our method only permits us to identify the maternal origin of the hybrids, differentiating mules from hinnies,” they explain.

“However, the phenotypic (visual) differentiation of mules from horses and hinnies from donkeys is not a problem for breeders and ranchers, according to our field experience. Therefore, the pivotal problem is to distinguish mules from hinnies and for this, the method presented in this study is very effective.”

They believe that their technique will allow a fast, cheap, and easy way to accurately differentiate hinnies and mules.

“This method can help breeders, ranchers, horse associations, animal science professionals, and researchers to manage their equid herds and pedigree registers with more confidence and precision.”