A Note about Sugarbush Draft Horses
I see it over and over again, and no matter how many times it's said, it's still wrong. "Sugarbush Drafts are just an Appaloosa Draft Cross". Uh.... no. The Sugarbush Draft Horse was a breed created many years ago in Ohio. While the initial cross was made using Percherons to Appaloosas, in the many generations following, the breed has been solidified into a consistent type. Saying these horses are "just" a draft cross makes as much sense as saying that AQHA horses are "just" a Thoroughbred cross, American Cream Drafts are "just" a dilute Belgian, or that Morgans are "just" a grade.
Tuesday, September 21, 2010
Appaloosa colors and outcrossing
Now, pardon me while I completely enjoy dorking out on how it works....
As we talked about before, Appaloosa color has 3 main components: LP, pattern genes, and enhancer/supressor genes. If you don't mix all of those right, you don't get flashy color.
A horse with LP only, no dominant pattern genes (because they still have the gene, just the alleles there are all recessive patn) and enhancer/supressors that have no pattern to work on, those horses are pretty boring color wise. Here's an example:
Now THIS boy (Quagga's last foal, and the last horse bred by Siggrid Ricco, my mentor) is much more fun to look at:
And it's mainly because of those pesky pattern genes. Sadly, pattern won't show up on its own. And these lovely polka dots require both a dominant and a recessive copy of LP to show up. I also have to point out here, that this guy is a half brother to the mare in the first image of this blog (Chestnut mare being lunged). She's rather poorly colored, and Siri here.... WOW!
Here's a horse with a similar pattern, but that is homozygous for LP:
Again, pretty boring to look at, eh? So you can see how the prettiest patterns need a bit of everything to make them so bold and exciting.
Well, when you breed to appaloosa colored horses, you can see their pattern (little a meaning those that show the appy patterns, regardless of breed). That makes things a lot easier. Sadly, if you keep breeding color to color, you increase your chances of getting the last type of horse, the homozygous dominant LP horse (fewspots or snowcaps). So, the best way to get lovely loud colors is to breed fewspots to solids, then you're guarenteed of at least the ideal alleles at one locus: LP/lp.
But, because we can't see pattern genes on solid horses, it's so hard to know what you're getting from the solid mares. We really have 2 options, get lucky, or research the hell out of it. I like option #2, if you couldn't tell.
Now, statistically speaking, horses from appaloosa ancestry, especially Appaloosas and Knabstruppers, tend to carry the pattern genes. It's very very rare to see a Knabstrupper that is just a roan (like the chestnut filly I showed). This is because Knabstruppers were bred for leopards for quite a while, and it tends to be a very common pattern gene for them. Appaloosas on the other hand, have a much wider range of pattern genes, and many tend to have a lot more dominant pattern genes (blankets, leopards, and everything in between).
And while normally I don't get into ApHC politics, that doesn't mean I don't keep up with them. I just feel that because I'm not currently an ApHC member, I really don't have the right to talk. My main focus is on another LP color breed, the Sugarbush Draft Horse. But, the ApHC allows horses to be bred to Arabians, Thoroughbreds, and Quarter Horses, and the resulting foal is a purebred Appaloosa.
This is scientifically acceptable as a "purebred" which is hard for a lot of people to understand. But the scientific definition is really pretty boring. It's a select group of individuals that when bred within the definitions produces a predictable result. That's it. If you can cross Clydesdales to Thoroughbreds, and get the same thing everytime, or within the same range, then you have a scientific purebred animal. Whether you like that type of breeding or not, does not refute that it's a "breed".
Now, when talking about color though, you have to consider the ramifications of breeding to that outside group of genes. I'll use my breed, so as not to ofend any one, because the idea is the same.
With Sugarbush Drafts, we have so few horses left, and most of them are from the same bloodlines. In order to breed IN color, we have to breed way back on the percentage of draft blood. A single generation of crossing back to a light horse results in many generations of breeding to get back to the ideal size/weight. But, if we breed only to draft horses for genetic influence, we will likely lose the color the breed was known for.
Percherons tend to be one of the favourite crosses for the Sugarbush Draft horse (I think it's the black). Now, until there's a genetic test this is only a theory, but it appears that Percherons only have recessive pattern genes. Foals from a Percheron parent tend to have a 50% production of offspring with pattern. Since they can only be at most LP/lp from a Percheron parent (since Percherons are always lplp) this means 1 in every 4 foals will have the ideal color. That's a 75% "not what I want" rate. Remember, I'm only speaking about color here, not advocating for breeding purely for color.
Now, Belgians seems to have some minor pattern genes. Lacy blankets, maybe even small blankets. Of course, Belgians also tend to have some face and leg white, which we talked about before can do double duty as a pattern.
Clydesdales though, they are weird. All that white on their faces and legs... but the pattern results are much lower then expected. Clydesdales HAVE pattern genes, but they also have a LOT of suppressor genes. This means that a foal with a minor pattern could have it suppressed down to nothing.
Here's an example:
I have yet to do studies on Shires, or the other drafts, so I won't go into them.
Now, if a Sugarbush person wants pattern genes, they can easily go back to breeds that are known to carry them. Andalusians/PRE are one of the best. Shocked? You shouldn't be, because they are the line that started the whole thing. The appaloosa color is directly descended from the Spanish Horse, which over time because the Pura Raza Espanola, known in the USA as the Andalusian. Other breeds with good pattern genes are Lusitano, many of the Pasos, Halflingers and Norikers. Sadly, Norikers are rarely seen outside Austria.
If I could only get my hands on a few Norikers.......*daydreams*
But, anyways...My point is, that breeding to these pattern rich breeds, you can likely increase the color by outcrossing. On the other hand, if you breed to a breed of horse that is not known for pattern genes, you will simply be guarenteeing yourself a recessive allele that can and will be passed on to future generations.
Now, keep in mind that when we breed horses we are selecting for genes that we can see. Want a lovely head, then you select for those genes by breeding the good heads, and gelding the ugly heads. Want more size, then select for it. But since pattern genes can't be seen without LP, they are rarely bred for in most solid breeds. Warmbloods, Thoroughbreds, Arabians, drafts... think of all the breeds of horses that do NOT have appaloosa color, and all of those breeds could, or could not, have pattern genes. No one breed for them because you can't see them.
Interestingly, Quarter Horses are notorious for not having pattern genes. Great examples of this are the "surprise" appaloosa offspring that result from 2 Quarter Horse parents. These horses are proof that LP has been passed down through the generations, with so little pattern or such limited roaning, that it was overlooked.
I often hear the logic that because appaloosa colored Quarter Horses do show up, that they must have a lot of color production ability. Sadly, that's not how it works. Because the color lays "hidden" for so long, and LP is a dominant gene that can't hide on its own, it actually proves just how unlikely it is to get a pattern gene from that breed. If pattern genes were everywhere, then those "surprise" appaloosa marked Quarter Horses would be popping up in the vast majority of the LP carrier's foals. Instead the LP is passed along for generation after generation with no one the wiser.
In other words, a stallion with LP hiding in something like roan, would have a HUGE amount of appaloosa marked foals. A mare with LP hiding out would be known for dropping appaloosa marked foals. So it would be a known line of "crop out breeders" for many generations back.
Check out this mare:
But, she's a perfect example of a horse with no pattern. Until she was bred to a stallion with some serious pattern genes to pass on, her foals would never get pattern. It doesn't just appear from nowhere.
On the flip side, here's a mare with a leopard pattern gene:
How many of you can see any signs of leopard? (yes it's a trick question, this mare is lplp so a true solid). But, this mare is of leopard to leopard breeding. The chances that she did NOT get a leopard pattern gene is only 25%. If you get crazy with the math, and look at the chances of inheritance of her parents, it's very likely that she's PATN1PATN1, or homozygous for leopard pattern.
Let me explain that. Statistically speaking, a horse will pass a gene 50% of the time. This is because when the gametes are formed, the DNA is divided in half, equally. So, if a horse is LPlp, then half get LP and the other half gets lp. If a horse is LPLP, then half get the first LP, and half get the second LP. Clear as mud?
So, if you start to look at the big picture, her sire should have had 50% of his foals get his leopard pattern. Her mother should have had 50% of her foals get her leopard pattern. That's a 75% chance for a single foal to get a leopard pattern from this cross. The numbers didn't work out that way when we looked at the foals. So, we know that the chances of him passing the leopard pattern didn't change, but likely, the horses who couldn't SHOW that leopard pattern got the genes - the solids. When you add in the numbers of the dam, well.... this mare is a winning lottery ticket.
So, like I said, outcrossing could very well reduce the amount of pattern, or visible color in the ApHC's gene pool. We already know it is decreasing the pattern genetics in the Sugarbush gene pool, and are working hard to bring it back in. Because the Sugarbush gene pool is wide open right now, we have the options of going back to breeds that will increase our chances of color, but the ApHC doesn't give their members that option. They can only use 3 breeds, Arabians, Thoroughbreds, and Quarter Horses. One of those breeds is proven to have limited pattern genes.
So, when asked if outcrossing will reduce color in the breed(s), the simple answer is, "Maybe". It really depends upon what breeds you're crossing your appaloosa colored horses with.