Hi All,
I had a question some what like the one asked. I wrote to Vicki/Ladywife, owner of DonkeyMuleInfo group. She has a site here,
http://www.donkeymuleinfo.com . The following is what she sent me. She is very knowledgeable, and has been in donks over 30 years.
I did see first hand, my jennet, Honey, who was just over three months old then, with her butt backed as far as she could up to the fence, showing for my mini horse stallion, Macho. She was hurtin!
It was so funny to watch!
Hope this helps!
Jim Guerin
Yelm, WA
JENNET ESTRUS CYCLING
A jennet is in estrus influenced by FSH (follicle stimulating hormone) and
OEST (estrogen) for an average of 5 to 7 days, some jennets longer, some
jennets a shorter time. It depends on their age, health, diet, and
reproductive history. During estrus she will stand for a jack. Indications
are tail up, winking of the vulva, and she will have a relaxed cervix and
moist vagina. During the final 18-24 hours of her heat she will ovulate but
there is a narrow window of opportunity averaging 12-18 hours for sperm
introduced to fertilize the egg. You may see a sticky, mucus discharge on
the lips of the vulva when she ovulates. If you miss ovulation by as little
as a few hours no conception will occur because the egg has already been
ejected. It only stays viable for a short time. The instant the egg is
released from the ovary it triggers the production of LH (lutenizing
hormone) from the pituary, and PROG (progesterone) from the ovary and
usually within 24 hours after ovulation dioestrus begins and there is a
dramatic change in the jennet's behavior and she will lay her ears back and
kick at a jack. Her cervix is closed and her vaginal tract is dry.
Dioestrus can last 16 to 30 days depending on the jennet and then a new
estrus cycle begins and the pituary begins producing FSH and the ovaries
produce PROST (prostaglandin). From ovulation to ovulation the average is
21 days but I have seen it as short as 18 days and as long as 39 days.
Jennets under the age of 6 years old can have erratic heat cycles especially
those under the age of 3. Jennets begin cycling at only a few months old.
The youngest I've seen personally was 4 months old and so its important not
to allow young jennets exposure to a jack, even jack foals. Those baby boys
are born with viable sperm but lousy aim. While they are practicing they
can accidently hit the target and impregnant a jennet foal. Jennets usually
cycle year round but during the heat of summer and cold of winter their
cycles may be silent and they won't display. Vicki/ladywife, DonkeyMuleInfo Group owner