A jenny is the term used to describe a female ass or donkey. Occasionally, a female mule is referred to as a jenny, but more often, the term "molly," "mare" or "mule mare" is used. In western Canada, the term "jennet" is sometimes used instead of "jenny," though the term Jennet usually refers to a type of horse popular in the Middle Ages. One archaic term for a jenny was "she-ass." An intact male donkey is called a "Jack."
Jennies have a 12 month gestation period, longer than the 11 month gestation period of the horse mare. Their actual gestation can range from 11 to 14 months.They also have a lower conception rate; the conception rate for mares is approximately 60 to 65 per cent, the conception rate for Jennies is lower. Twins are rare, but occur more frequent among donkeys than horses. They have a seasonal estrus (heat) cycle, which, in the northern hemisphere, begins in March, and occurs every 21 to 28 days.
A jenny will come back into heat nine to ten days after foaling. However, unlike mares, jennies are usually not bred back on this "foal heat" because their rate of conception is low, probably because the reproductive tract has not returned to normal. Jennies are usually very protective of their foals, and some will not even come into estrus while they have a foal at side. The time lapse involved in rebreeding, combined with the length of a jennet's gestation, means that a jenny will produce less than one foal per year. Breeders plan for three foals in a four year period.
- ↑ 1.0 1.1 1.2 1.3 http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex598 "The Donkey", Alberta Agricultural and Rural Development. Web page accessed March 4, 2009
- ↑ Sewell, Sybil E. "Foaling out the Donkey Jennet" Alberta Donkey and Mule.com. Web page accessed March 4, 2008
- ↑ Rachau, Jeanine A. "Gestation and Foaling of Donkeys"