mule reproduction? - The Horse Forum
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post #1 of 17 Old 02-13-2010, 06:33 PM Thread Starter
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mule reproduction?

Ok, so this may be a stupid question, but it just popped into my head today and I wondered if anyone knows the answer.

So mules are almost always sterile, but the do come in heat and all that normal stuff. My question is can they carry a foal? Like as an embryo transfer recipient mare?
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post #2 of 17 Old 02-13-2010, 06:40 PM
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There have been occassions where Mules get pregnant and give birth - but most of the time, the majority are infirtile.

They are a man made species, they lack cromosome's. Horses have so many and Donkey's have so many needed to reproduce, where Mules lack.

They have uterus's and yes, they go through heat cycles - I had a Mule name Molly who would squirt, and I've seen her breed with the Mammoth Jack Donkey that lived on the same farm *he was turned out with all the mules* but she would never get pregnant.

Can they carry a foal? I don't know - that is something you'd want to discuss with a Vet who specializes in this field.

I grew up in the same neighborhood a lage Mule Farm was. I got the priveledge of getting to know Mules and working with them on a daily basis. I learnt alot about Mules :)

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post #3 of 17 Old 02-13-2010, 07:23 PM
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great question. i spent years doing embryo transfers, and i do NOT know the answer. i will find out though. we did experiment with some spayed mares, but never tried mules.
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post #4 of 17 Old 02-13-2010, 07:25 PM
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apparently they can carry an embryo, if they are cycling mules. some cycle some don't. according to an article from Argentina
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post #5 of 17 Old 02-13-2010, 07:27 PM
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I worked for several years on a guided ride farm where half our string were mules. I have a real love for them, and plan to get a mule someday.

Mollies definitely come in heat, and the boys still need gelded because although sterile, they will develop all the normal studdish behaviors. I don't see why the mollies couldn't surrogate, all the parts are still there. I guess I never really thought about it. Interesting question, I hope someone on here will know the answer!
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post #6 of 17 Old 02-13-2010, 07:41 PM
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Happened upon this by coincidence:

"A mule has given birth to a male foal in a hamlet deep in rural Morocco. The 14-year-old mother mule gave birth on 28 August, 2002 in a small hamlet of three poor farms in the region of Oulmes, 80 kilometers south of the ancient city of Fez. The farm is nestled at the foot of the Atlas mountains, where the mother mule has become a cult. She and her foal have been visited by streams of people, many of whom traveled for hours to pay tribute to the miracle birth and bring gifts to the owner and the animal. The mule has become a local attraction The mule's aged owner, a farming woman whose face is covered in traditional local tattoos, did not realize the mule was pregnant and rode her 20 kilometers to market the day before the birth."

"No big deal, you may think, but in fact the birth was a minor scientific miracle. A mule is the hybrid of a horse and a donkey and should be sterile - except in this instance. There have only been two substantiated cases of a mule giving birth in the past quarter century: one in China in 1988 and the other also in Morocco in 1984. A horse has 64 chromosomes and a donkey has 62, so a mule is left with 63, an uneven number which cannot divide into chromosome pairs. This normally makes a mule unable to reproduce. However there have been, since 1527, (when records began on the issue) a total of 60 reported cases of mules giving birth. "The occurrence is so historically rare that the Romans had a saying Cum mula peperit, meaning 'when a mule foals', the equivalent of our 'once in a very blue moon'," explained Dr Gigi Kay, a horse vet with the charity, the Society for the Protection of Animals Abroad ."

Original article from the BBC, I found it here (at the very bottom)
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post #7 of 17 Old 02-13-2010, 07:50 PM
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what breed would you call the baby of a mule? A jack, a foal, or a cross?

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post #8 of 17 Old 02-13-2010, 07:57 PM
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I'm sure there has been a mule give birth in the U.S. as well, I'll have to look for it. I remember reading about it in Equus magazine sometime in the 80's *l* The molly had two foals, two years apart, both out of a donkey jack. I remember it because she named the first foal "Blue Moon" and the second foal "White Lightening" and I have a stupid memory for stuff like that. Maybe it was later proved to be a hoax or something like that.
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post #9 of 17 Old 02-13-2010, 07:59 PM
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tempest, I think it would still be a foal. A Jack is a male donkey. A Jenny is a female donkey, and a molly is a female mule, but I can't remember what a male mule is called, or if it is still a jack. I know mules themselves are still called foals when they are born, I don't think that particular terminology is different.
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post #10 of 17 Old 02-13-2010, 08:02 PM
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For the sake of discussion, yes, mules are always sterile. But, as there are exceptions most all rules, fertile molly mules have been reported.

In most cases, the mule's baby is born either a full donkey or a full horse, depending on who the father was. (Mule + donkey = donkey foal, and vice versa.) In rarer cases, however, an actual baby mule (a mixing of donkey and horse genes) is born. We can not explain this. It's a wonder of nature. One of these cases was Dragon Foal, a mule born from a mule mother in Asia, and Blue Moon and White Lighting, two mules born in the US to the same molly mare a year apart. (I believe the father, a donkey jack, was the same to both babies.)

And yes, mules can be used for embryo transplant. Their reproductive systems work perfectly well, so they can carry a baby, produce milk, ect. The only problem is that unfortunate chromosome count. Also, molly mules are famous for stealing babies from others! Some of them really, really want to be mothers.


A jack is an ungelded male mule, a molly (or sometimes called a jenny or jennet) is a female mule, and a john is a gelded male mule.

Last edited by Brighteyes; 02-13-2010 at 08:05 PM.
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