Donkey than hinnies, making them more desirable for breeders to produce. The offspring of a zebra-donkey cross is called a zonkey, zebroid, zebrass, or zedonk; "zebra mule" is an older term, but still used in some regions today. The foregoing terms generally refer to hybrids produced by breeding a male zebra to a female donkey. "Zebra hinny, zebret" and "zebrinny" all refer to the cross of a female zebra with a male donkey. Zebrinnies are rarer than zedonkies because female zebras in captivity are most valuable when used to produce full-blooded zebras. There are not enough female zebras breeding in captivity
Domestication of the horse less than expected based on the overall genetic variation in the remaining genetic material. This indicates that a relatively few stallions were domesticated and that it is unlikely that many male offspring originating from unions between wild stallions and domestic mares were included in early domesticated breeding stock. Genes located in the mitochondrial DNA are passed on along the maternal line from the mother to her offspring. Multiple analyses of the mitochondrial DNA obtained from modern horses as well as from horse bones and teeth from archaeological and palaeological finds consistently shows an increased genetic diversity in the mitochondrial DNA