Lack of selection because of the difficulty of controlling donkey breeding is, therefore likely wherever a premium is placed on “wild” characteristics of the donkey, such as strength, rather than on docility and productivity for food. The relatively high proportion of males in herds (one male: two females) is another factor that makes control over breeding logistically difficult.
The greatest factor contributing to the adaptation of the Ass may be related to its functional anatomy, biology and behavior. Donkeys are miniature creatures with slender bodies and anatomical built that permit them to support load over 60% of its live weight. They have shown remarkable stamina and resilience to move long hours without food and water.
The hooves are the narrowest and smallest of any equid to effect long distant journeys. In equids, the pectinate ligament is more prominent than in ruminants and characterized by sturdy interconnected strands and relatively small intertrabecular spaces. Each aspect of donkey is interesting in breeding programme (even behavior or body weight=power).
