Stallion reproducing himself- When does a mare improve the stallion OR can taht breeding do so? - ONLY breeders please

Someone on another post noted that " Birdstone (the Brelomomnt winner) reproduced " himself… plain, small,…". Essentially I got from these comments that his “outcome,” is not what the commercial or competitive desired. . When if ever can the mare “improve,” what the stallion brings to the table? Recognizing that genetics, chance, possibility, probability, and LUCK all play a role in what one may get in the end at the end of those 11 months!. Clueless here but would liketo hear the thoughts from that DO know something on this topic!

The mare and the stallion each contribute 50 per cent of the DNA. Stallions can sire thousands of foals in a lifetime while a mare can at most produce say ten. So there are more offspring to view for prolific stallions and more attention paid because the breeding is a business.

Some stallions are prepotent meaning their offspring tend to resemble them in key aspects. That could be because they are genetically more homozygous. In color, like a perlino will always sire dilutes and a homozygous pinto will always produce some amount of color.

I think people tend to always want to breed to a stallion that will “improve” the mare. So by definition wanting a stallion better than the mare for whatever purpose or goal. Obviously if the reverse happens then the mare improves the stallion. Your gorgeous Arabian mare is pasture bred by an ungelded fugly grade yearling. Foal will look prettier than the father for sure.


See, I do not completely agree with you here.

I really have found over a very long time at breeding (since 1979) that that mitochondrial dna is a trump card, most of the time. I bred some TBs, some ASBs, and some crosses. I saw it happen over and over again, and I learned to select my own mares accordingly.

I absolutely believe that there are some stallions who throw particular traits consistently. However, I will go with the mare’s strengths, and add what I would like to add with a stud.

Two examples- I had a gorgeous dappled grey TB mare from a family known for their floaty movement. She ALWAYS produced it. So, it was just a question of dialing in some other nice things from a stud.

I had an amazing ASB mare who also always produced her movement- AND her slightly volatile personality. I tried to be sure not to double up anything in her breeding that brought the temper to the table, and went for elegance. She produced the stallion who still holds the record for an ASB sport horse score. He was still brilliant, but a bit less challenging, even as a stud.

And conformation wise, I never try to correct a mare with a stud- I want to start with a correct mare.

Just my .02



OP, most TB race stallions have to bring a certain amount of pedigree, looks and race record to the table. The breeder looks at the conformation of his first foals, and then at how they look and move as yearlings. After the first crop gets to the track the owner can begin to see which mares are producing his stallion’s best runners and try to build on his success by breeding him to mares from similar lines. (See “True Nicks”.)

This process continues with each crop until the breeder has a good idea which mares work best with him, or concludes, along with mare owners, that he not getting the sort of racehorses they want and he fails at stud.

In TB race breeding, the mare’s tail female line is as important as it is in the breeding of other performance horses. The difference in my experience is that some racing breeders will breed an unraced mare or one that wasn’t successful on the track if she comes from an exceptional female family. There are some good racehorses that have unraced dams or dams that didn’t take to the track.

That was not the case with the breeders of sport horses that I worked for, who insisted that their mares be very capable of doing the job as well as having the pedigree before they were used for breeding. They were “old school” TB and Arab breeders respectively.

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Many thanks… that is what I meant. I’ll often hear on the gossip line (not sure if it is true or not} that “Justify has an offset knee… I had to make sure my mare had gorgeous legs…” I recall from animal genetics taken at KSU 10 years ago that you can’t correct a structural flaw, but you are looking to improve production or performance. Is that right???

Family in Germany does dressage and show jumping… that is their mentality y with thier mares. They want performance , looks and motherhood with their mares! Ever notice that the Germans often have a lot of super talented mares on the jumping teams or just competing ion the shows?


Many thanks, most appreciated. With that mentality one would only be breeding an animal of quality. I don’t mean a “world beater,” or super show horse ," but a well conformed, mentally sane" horse that one would be proud to own or be around… and really enjoy.

Living in KS I saw alot of accidental or backyard breedingsbecause many did not geld between yearling and two years old. Generally it was not the best outcome.

Because mares can only have one foal per year maximum stallions are held to a much higher standard than mares tend to be, therefore you are hoping the mare will produce a foal that equates or exceeds the higher standard that the stallion possess. Ideally that higher standard comes not only from their performance but also from their physical traits. When a stallion out performs what he appears to be able to do ala Birdstone they give him a shot to see if he is capable of siring foals who will also be able to out perform what they appear to be able to do physically by giving them some very nice mares to see they can improve him physically.


Breeding should never be done to correct anything - you can’t take a club-footed horse, breed to a perfect-footed horse, and reliably get anything but closer to one or the other, and that may well be that clubbier foot.

Most people want to improve the mare, because they’re the ones going out looking for the breeding. BUT, some stallion owners do become very selective about mares they accept if they know their stallion has a few shortcomings and needs a VERY correct mare to not make the stallion look bad.

There are some stallions who outproduce themselves on a very regular basis. But they are already stallion quality in and of themselves, they just get improved on. That’s making some assumptions, sure, as the dud down the road who doesn’t deserve fuzzies, could be bred to a whole lot of nice mares and produce a reasonable amount of foals nicer than himself (but rarely as nice as the nice mare).

Other stallions reproduce themselves, nearly to a T, with few exceptions.

And likewise, some mares reproduce themselves, with few exceptions.

The mtDNA is very important, and many breeding circles ignore it. It is why many who clone mares want the donor to be of the same family line as the original - it matters, sometimes a lot. Good TB breeders, good WB breeders (especially in certain registries like Holsteiner), a few QH breeders I’ve seen, and probably some other breeds, pay critical attention to female lines. Others place allllll the emphasis on the stallion.

A lot of this depends on what you mean by “improve”. Some people value a shorter back vs longer, for a given discipline, but unless you start with TOO short, or TOO long, it’s all subjective. I would never breed the too short/long horse because you could easily end up with a foal who is too short/long, even if may be less “too”. That’s trying to correct a major enough fault. Don’t do that.

But if the mare has a shorter-than-desired back, and the stallion has a longer-than-desired back, but still within the realm of correct, the foal can have a more subjectively improved back. But who did what? Did the mare shorten the stallion’s back, or did the stallion lengthen the mare’s?

Some things we know are very heritable - movement and jumping form to name 2. It seems that jumping form is easier to “ruin” with breeding, as there really is truth to some horses being “jump killers”. But an ok but not A+ jumping form stallion could be improved by an A+ jumping form mare from a line of A+ jumping form horses. That said, I’d never breed “down” in that area if I was looking to produce an A+ Hunter

It depends on how far off the mark the flaw is. Minor flaws can be corrected, or improved, but you might also get the same minor flaw. It depends on whose genetics win. But if, say, the offset knee is on a scale of 1-5, and you start with 5, you’re not going to get a 1, it will be somewhere in the middle, likely closer to one parent or the other.

I would argue that most top WB breeders are all about the dam line, whether that be Dutch lines, German lines, etc. A proven dam line produces and produces.

Knowing what the dam produces is key. The traits the mare doesn’t pass to her offspring have the potential of being passed and possibly improved upon by the sire. But truly, if you aren’t happy with a carbon copy of the mare, especially temperamentally as she is raising the foal, then the mare should not be bred.

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For me, the mare must be adequately conformed, and must have done something to “earn the right”. Her pedigree must have some redeeming factors, that I, personally like. Somebody else may have different ideas than I do, and that’s OK. But I have to be “a believer”, for some reason. She has to have a disposition that tells me that she’s going to enjoy being a mother, and do a good job… because there’s nothing worse than a mare who is not a good mother, no matter what her other strengths may be. She is probably not going to ever produce enough offspring to PROVE exactly how often her strengths come through, but sometimes I can have my opinions and see some similarities.

The stallion’s get… you have to know a lot of horses personally, to really know much about them. With local stallions, if you work at the track, you will get an opinion of what the similarities may be between offspring. Their suitability for the job, how they take to the training, how successful their offspring are, and what the similarities are between offspring of a single stallion.
So, for me, it is only me that knows the mare, and can see her influence in her offspring. It may or may not come through. No horse is perfect, and not every horse is successful in it’s stated goals.
And it’s always a crap shoot with breeding horses, nothing is ever certain. We develop our theories, and act on them, make our selections, raise and train the result. Sometimes we win, sometimes we do not win. If it was easy or straightforward, anyone could have success, and there would be less guesswork in the pursuit. And just when some people think they’ve got it all figured out, a horse comes outta nowhere, and turns the whole system on it’s head. That’s what keeps it all interesting, and keeps the “little guys” in the game.


I would want a lot better than adequate :slight_smile:


By the 3rd foal, you have a very good idea what the mare produces.

Breeders are a tight knit group. Everything is shared - from semen analysis and number of successful pregnancies by each stallion, to what each stallion is stamping in progeny, to competition and performance results, to what foals are selling for by particular bloodlines, etc., etc.

You’re right, breeding can be a total crap shoot, but there are ways to make the process a bit more methodical to keep all involved a bit more strategic and a tiny bit (tiny, tiny bit) more sane.


Not necessarily. Temperamentally, the mare is always going to contribute more than the stallion because the mare is raising the foal.

There are also sires who are heavy stampers that will reliably stamp a certain hind end, neck attachment, loin connection, size, etc. etc. There are some stallions that stamp very little and leave most to the mare. Limbs can be quite hard to modify and the heredity of limb conformation is over all questionable (and maddening).

And then sometimes, you get the influence of grandparents in the mix which makes things very interesting. I’ve found this to be true with type, movement, color genetics, etc.

There are certain stallions in my breed that do stamp their babies. I’m always amazed at how phenotypically prepotent the ASB’s are. For those of us who spend time trying to re-unite horses with their identities, it is useful to know which lines produce what. You can narrow things down pretty quickly. I will say that there was one mare who absolutely stunned me when they finally got DNA on her. It happens.

Still in all- the mares prevail. You might get color from a certain line- blonde manes, lots of white. But body type? I’ve found the mares to be the driving force in that.


Statistically each parent contributes on average 50 per cent of the straight DNA genetic material.

But absolutely the mare contributes all the environmental and epigenetic effects. An interesting example is the huge difference between mules and hinnies. It would be interesting to see how foals from surrogate mares compare to foals born to the egg donor mare.

My understanding is that the more homozygous the parent, the more they are likely to produce foals that are phenotypic ally similar to themselves. Friesians are very homozygous and half Freisian foals are very typey. And usually black IME.

A more crossbred or F1 cross horse could be carrying a more heterogeneous mix of DNA that is not fully expressed in his or her phenotype. So you are less likely to get a carbon copy of a dam or sire that is say a TB/Percheron cross.

Responsible or ambitious breeders and stud services tend to have stallions that have solid coherent lineages and may be more homozygous than the average mare or gelding. These stallions may stand a higher chance of producing a foal that resembles them phenotypically rather than an unexpected throwback to wierd great grandpa. Because the stallion already looks like his great grandpa…

But mares can also be homozygous. In that case she might well produce foals that resemble her.



IME, when using purpose bred lines with often a higher inbreeding coefficient and smaller genetic pool, homozygous traits are more prevalent in progeny. I do not envy breeders that are producing offspring from very diverse types.


Parents’ genotypes are the defining and limiting factor when it comes to color. You can tell genotype by phenotype in some cases, but not all.

What gets tricky are the recessive color genetics which are “carried”, but not visible, in the parents. You can have 2 bays, from a long, long line of bays, and produce a chestnut, for example.

But no matter how many grays there are behind the parents, if neither parent is gray, you’ll never get a gray foal

It’s a straight 50/50, until you get to the offspring being a filly, and then the mare contributed her MtDNA

What isn’t so “straight” is who contributed the dominant gene of the pair. If you’ve got 2 horses each with a recessive and dominant “setting” for a given gene, it’s a 50/50 each breeding who passes which, but every time, each contributed 50%

it only seems like one or the other parent contributes more, if s/he has 2 copies of the dominant setting, therefore always passing it on, and always showing up in the offspring

That’s how horses get to be known as prepotent for X, including body type.

Yes, exactly, which is why a lot of line breeding is done, to concentrate the desired genes, while weeding out the undesired genes. It doesn’t always happen, sometimes undesirable recessive traits get homogenized and we end up with problems.

Yes, F1 Friesian crosses are often black, but just as often, and probably more often, they are bay. There are lots and lots of bay (so Aa or AA) horses, and chestnuts carrying Aa or AA. Black is the least common color because of what it takes, and Agouti is pretty commonly “on” in a large % of horses, because bay dun was the original horse color. Everything else is a mutation

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Very much agree. I wrote my comment with a 2021 colt that I bred in mind. The colt is a 5th or 6th generation black colt (I believe all with 4 white socks) from the sire line yet the sire is not homozygous black. He is from German WB lines with a touch of Dutch in the pedigree, but has a unique facial marking, 4 white socks and was born with blue eyes. Some blue remained in the eyes. I wish to test him for the W20 gene because he is suspicious for it. His dam is from a homozygous (black) sire but is not homozygous herself; the colt’s sire is neither homozygous but consistently produces black babies with W20 characteristics. De Niro is a grand parent and said colt shares the same unusual facial marking and coloring. It’s interesting. I believe we are starting to see W20 in WB lines but I haven’t proved it yet. :slightly_smiling_face:

I wonder about the affect the recipient mare has on the embryo transplanted foal as well. It would be a fascinating study. I hope someone is looking at it.