The chart I’m looking at 53.1, 37.9, 33.0, 24kg for, respectively, TinT, PinT, TinP, and PinP.
Pony foal in TB mare was 38kg (83lb) , vs TB foal in Pony mare at 33kg (72lb) vs Pony foal in Pony mare at 53lb.
I find no reference to the height and weight of the pony mares - did I miss it?
It’s not nearly as interesting a study if the ponies were all in the 14h range and the TBs all in the 16h range.
The maternal weight is in table 2.
There didn’t seem to be much range in weight in the mare groups, so why do you think there was much variation in size within groups?
Ok, so, 1313lb and 1278 for the TinT and PinT (about a 3% difference small to larger, not too much), and 781 and 660 (18% difference small to large, that’s pretty significant I’d think) for the TinP and PinP mares.
Is that their pre-pregnancy weight? Late gestation weight? I saw some reference to pre-maternal weight (weight .75) but am not sure.
Short wide ponies or tall narrow ponies?
It also makes no mention of the sires of these foals. The best test would be sires very similar in build (height, weight) as the dams, and known to produce similarly sized offspring.
As stated in the paper looks to be post partum weight.
There are a couple of real outliers in the pony group (2 that carried TB foals), otherwise they look pretty tightly clustered. TB mare weights look to be over a 350 lb range, which sounds like a lot, but I’ve seen a 150 lb difference in the same horse, with neither being an outrageous extreme. lol
Who knows about the phenotype of the pony mares, or how that affects the size of the uterus or placenta. Such data would be useful but could be hard to quantify. Wouldnt it be difficult to determine internal pelvic width? – you’d need to do that before determining how reliable of a characteristic external pelvic width is, unless someone else has already done a study on that relationship.
As far as sires go, I would imagine that they used ponies that throw ponies, and horses that throw horses. Perhaps they threw common sense to the winds and did something different, but that would confound the experiment, so…
As stated in the paper looks to be post partum weight.
From figure 4: there are a couple of real outliers in the pony group (2 that carried TB foals), otherwise they look pretty tightly clustered. TB mare weights look to be spread over a 300-350 lb range, which sounds like a lot, but I’ve seen a 100 plus lb difference in the same horse, with neither being a completely outrageous extreme, believe it or not. Muscle mass can make a big difference in weight.
Who knows about the phenotype of the pony mares, or how that affects the size of the uterus or placenta. Such data would be useful but could be hard to quantify. Wouldn’t it be difficult to determine internal pelvic width? – you’d need to do that before determining how reliable of a characteristic external pelvic width is, unless someone else has already done a study on that relationship.
As far as sires go, I would imagine that they used ponies that throw ponies, and horses that throw horses. Perhaps they threw common sense to the winds and did something different, but that would confound the experiment, so…
Given the number of skeletons out there that are studied, the number of horses used for university studies over some period of time, I would think that someone has figured out a fairly reliable relationship between external pelvic conformation and the internal birthing width. But maybe I’m just an optimist lol
I think it was poor writing to leave out the info on the stallions and their history of production, and worse research to not take that into account, whichever is the case.
Yes, well, perhaps you can find that study on internal and external pelvic widths then. That would be interesting information.
You can claim that’s bad research not to include the sires and their history of production, but considering that they are going to throw a range of sizes and are not cloning themselves, that’s a rather weak claim. This paper is looking at the relationship between mare size and foal size and does a much better job of it than the early papers. Basically a genetically large fetus is undernourished in the uterus of a small mare.
[QUOTE=grayarabpony;6978841]
You can claim that’s bad research not to include the sires and their history of production, but considering that they are going to throw a range of sizes and are not cloning themselves, that’s a rather weak claim. This paper is looking at the relationship between mare size and foal size and does a much better job of it than the early papers. Basically a genetically large fetus is undernourished in the uterus of a small mare.[/QUOTE]
That is an assumption without knowing the mechanism by which the fetus size is controlled. I would doubt that is true or you would see greater health issues in those foals. Developmental biology is where we get stem cells from…this is not simple ideas. Elephants are pregnant for 2 years and at some point overall growth is arrested and only certain areas are developing.
I’m just saying - there ARE stallions who consistently produce bigger or smaller than the dam, either in size, or bone, or both. They only say that 1 TB stallion was used for all the TB embryos, and 1 pony stallion used for all the pony embryos, but that’s all I can find in that regard.
Additionally, this study, and the one on the Shire/Shetlands, were done using full TBs or full drafts and doing ET into pony mares. That’s not the same as a cross between the 2, where the genetics do mean the height and weight of the foal will be somewhere in between the 2, closer to one than the other, though a 17h stallion on a 12h pony mare, of pony breeding, is highly, highly unlikely to produce a 16.3h horse, as well as unlikely to produce something that’s only 12.3.
I am not discrediting this study or saying it doesn’t matter in the context of this thread. It’s got some really good information about the issues of the embryo that is genetically larger than the mare. In the end, this is a big key:
“However, whether these changes in growth and physiological function induced inutero persist into adult life remains to be determined”
As well, a better, more real-life study, would be to study what the OP is doing, with such a large height (and mass) difference between the stallion and the mare, and how those embryos develop in the small mare vs the large mare.
It also brings up a good point about nutrition - pony mares tend to be on the easier keeping side, and regardless of whether you’ve done ET of a large horse embryo, or doing a cross where the height difference is 5h (as is the case here), it’s going to be difficult to feed the pony mare enough food to provide the nutrition for the genetically larger foal (probably a good deal larger in this case).
Well, to be fair, they did find in this study that while the TinP placentas were larger than the PinP control group, they were smaller than the TinT placentas, so I think it’s pretty clear that the uterus is the final say in how big the foal gets (with exception, we’ll just exclude those because horses are full of exceptions :)). The genetics of the TB foal wanted a bigger placenta, but the pony mare’s uterus would not allow it to become as big as it was genetically predisposed to becoming, due to the physical restrictions of the size of her uterus.
I would doubt that is true or you would see greater health issues in those foals.
The article ends by stating it is not known how these issues follow the foal into adulthood, if they do at all. That’s something we really need and this group of horses would be perfect to follow. Anyone who understands enough about nutrition, and specifically people who have witnessed firsthand the issues of poor nutrition of a young horse, later in their life, see what happens when there is inadequate nutrition during critical developmental phases. It would have been ideal if these foals had had muscle biopsies and blood work done to take a look at any and all of the nutritional values that could be gleaned from those tests.
Developmental biology is where we get stem cells from…this is not simple ideas. Elephants are pregnant for 2 years and at some point overall growth is arrested and only certain areas are developing.
Same with horses, and I think that was why they pointed out in the end that the earlier birth day of the TinP foals was a problem - there’s only so much room for so long before it’s got to get out. We don’t know if the TinP foals were born they way they were - pre/dysmature in many ways - because genetically they needed to cook longer, or there were nutritional issues which were, as they suggested, causing the release of birthing hormones (closed the link, don’t remember the exact wording/term now). That gives pause for thought to the saying “the foal determines the day, the mare determines the hour”. Maybe the foal is not the final determining factor
There are PLENTY of big on little animals out there. One COTH poster had a big on little a few years back. she bred her welsh mare to her WB stallion.
She has re-bred the mare to other large horses too.
There are loads more of those out there. So it isn’t that experimental!
THIS!!!
[QUOTE=mbm;6979112]
There are PLENTY of big on little animals out there. One COTH poster had a big on little a few years back. she bred her welsh mare to her WB stallion.
She has re-bred the mare to other large horses too.
There are loads more of those out there. So it isn’t that experimental![/QUOTE]
Here is another example of a very successful large horse of 16.3 hands on a small pony of 12.3 hands - this breeding was done by a crazy European, not a crazy American:
http://foxcreekfarm.com/horse/Jimmerdor-de-Florys
It doesn’t look to me like there is anything wrong with that pony! 
Nobody is saying these breedings haven’t occurred before, even very successfully.
It’s just that there is more to it than finding 5h differences that DID work. How may did not because the foal - due to size things the stallion puts on them - was “too big” despite being size-restricted in the smaller uterine environment?
Studies are fine for those who like to use books vs experience, but when it gets right down to it, why gamble with your pony mare? I love mine entirely too much to play Russian Roulette with them. After all, there are enough things that can go wrong with breeding as it is. Using a pony mare to breed to a (much larger) horse stallion just is entirely too risky.
Just sayin.
[QUOTE=VirginiaBred;6979297]
Studies are fine for those who like to use books vs experience, but when it gets right down to it, why gamble with your pony mare? I love mine entirely too much to play Russian Roulette with them. After all, there are enough things that can go wrong with breeding as it is. Using a pony mare to breed to a (much larger) horse stallion just is entirely too risky.
Just sayin.[/QUOTE]
Every time you breed, you are gambling with your mare’s lives. And the practice side has been addressed. It is the emotional part (fear based on assumption) that is hard to address.
My fear is not based on assumption. In fact it’s based on reality. One of our very famous former pony mares was bred to a horse stallion and died foaling due to the foal being too large.
Every time you breed, you are gambling with your mare’s lives.
Yes, exactly…
fear is not based on assumption. In fact it’s based on reality. One of our very famous former pony mares was bred to a horse stallion and died foaling due to the foal being too large.
And likewise, one of my normal horse sized mares bred to a normal horse sized stallion also died due to the foal being too large. Should I now be afraid to never breed again?
I think for every situation one can always find examples to support whatever their point of view happens to be. For every foaling that didn’t work, an example can be found of one that did work. In the end that leaves us with a choice - live in fear, or continue forward. When my mare died some of my breeder friends asked me how I could go on breeding after witnessing that horrible birth - they asked me - aren’t you afraid of something like that happening again? Well, yes I don’t want to experience that again - but I also don’t want to be paralyzed into not doing what I want to do because I’m afraid it will happen again. Those are personal choices and no one is right or wrong in their choice - it’s just a personal choice.
[QUOTE=VirginiaBred;6979337]
My fear is not based on assumption. In fact it’s based on reality. One of our very famous former pony mares was bred to a horse stallion and died foaling due to the foal being too large.[/QUOTE]
That’s why studies aka books, are very beneficial. They are other people’s experience and it is only when you look at the bigger picture that you get an accurate one. Sorry about your loss.
[QUOTE=JB;6979051]
I’m just saying - there ARE stallions who consistently produce bigger or smaller than the dam, either in size, or bone, or both. .[/QUOTE]
There is a small Quarter Horse stallion near me–he is so small (14.1HH) they call him “Tony the Pony”. Tony has produced multiple ‘shoulder-locks’ to the point they are no longer breeding him. Its only smart to recognize that these scenarios DO EXIST.
Someone once showed me images of the results of some of these Draft x Pony crosses from one of the early studies. Mismatched does not begin to describe the horror of some of those crosses. I wish I could find the link—I cannot.
At least with respect to missmatched parts—I dont think you can even know at birth what you will truly end up with. I think only time will tell.
Keep in mind the draft x pony cross study that (at least) most of us are taking about are not crosses - they are full drafts ET’d into pony mares, and full ponies ET’d into draft mares. A draft x pony genetic cross is not something I’d EVER suggest doing, as the phenotypes and genotypes are just much too different.
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