When referring to animal traction and the use of this source of energy, mules assumed an exceptional role worldwide, providing power and transport at low cost, representing in the last thousands of years a cornerstone in the development and support of populations worldwide.

Mules (from a jack and a mare) and hinnies (from a stallion and a jenny) are the most successful hybrids in the family of equids. It has been claimed that mules combine the virtues of donkeys and horses, in what is known as the hybrid vigor: improved or increased function of any biological quality in a hybrid offspring.

Reputed for their hard work and strength, mules and hinnies were of paramount importance for centuries as robust working animals, usually performing heavier functions. These animals can effectively work in harder terrains, with its use being often favoured in more mountainous and humid type climates.

Thousands of years later, mules/hinnies are still kept for draft purposes and relied upon as a major source of traction all over the world, because of their desirable traits. Mules are able to work and tolerate extreme weather conditions, have enhanced disease resistance, and can survive on minimal feed inputs. These animals are essential to the agricultural and industrial activities, but also play a key role in the social and economic support in many of these countries, particularly in rural areas of limited income, where they present unique characteristics for sustainable animal production.

In the developing world, working equids are the most important source of agricultural energy and transport for resource-poor communities, in both urban and rural areas, and it’s even been suggested that animal energy supply approximately 50% of global agricultural power needs.

However, a collective ecological (but also economical) consciousness and an increase in awareness of public opinion about the need of reducing the excessive industrialization and mechanization of agriculture and forestry, along with an increased and renewed interest in energy and environmental issues has led some sectors of society to consider the use of animal traction as a valid modern source of energy. The need of maintaining biodiversity, reducing carbon emissions, encouraging self-reliance and reducing consumption of resources also contributes to this trend.

The emerging importance of animal traction as an alternative / complementary option to mechanical traction is highlighted by the increased use of such technology in small and medium sized farms (horticulture, vineyards, etc), where it has proved to be economically perfectly viable, but also in urban surroundings, in the collection of garbage in countries such as France or Austria. Even though horses are most widely used in modern animal traction, there is still a privileged space for the use of working mules in the same conditions, especially large European breeds, whose preservation depends directly on the need to reinvent functionality that adds value to these animals.


Rodrigues, J. B, McLean, A, Garrett, C. (2015) Animal traction and work. Volume 2: Functionalities of the donkeys. Current Donkey Production and Functionality. In Press.

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