Horse running through field

Native Dancer at the Vanishing Point

by Roger Lyons

Native Dancer has reached a genetic vanishing point in the sense that his influence is so pervasive that his contribution can no longer be contrasted in any significant way with the mainstream of the population. This is evident from the table accompanying my last post, which shows that in no instance do the strike rates of US stallions with mares in some descent of Native Dancer exceed their overall records. That is, no “contemporary” US stallion has a statistically measurable preference for mares in descent of Native Dancer. Keep in mind, though, that it’s because the broodmare population is so largely defined by Native Dancer. It’s like the air they breathe.

Moreover, only two stallions–Diesis and Dixieland Band–(that the table rather loosely defines as contemporary) fall below their normal strike rates when crossed with mares in some descent of Native Dancer, and they are both deceased. They were bred quite differently from one another with respect to Native Dancer–Diesis, by Sharpen Up, by Atan, by Native Dancer, and Dixieland Band, by Northern Dancer, out of Natalma, by Native Dancer.

Reasons can no doubt be given for why they had trouble with mares in descent of Native Dancer, but the fact that they did so has always had more practical import than the reasons why. More interesting here is that their aversion to mares in descent of Native Dancer and their shared birth year of 1980 renders their stud records especially useful as measures of the proliferation of Native Dancer’s influence.

Consider what it could mean that both of these stallions had significantly higher strike rates with mares born prior to 1985 than with mares born after that year.

Dixieland Band got superior runners from 50 of 435 individual mares born prior to 1985, for 11.5%; but, of the 644 mares born after 1984, 51 produced superior runners by him, for only 7.9%. Furthermore, only 23 of the 396 mares born after 1989 produced superior runners by him, for only 5.8%. As Native Dancer’s influence spread throughout the later population cohorts, Dixieland Band’s strike rate with those mares declined. Of the 219 mares with Northern Dancer in their ancestries, only 10 produced a superior runner, and he was barely in range of his average with mares in descent of Mr. Prospector.

Diesis’ stud record reflects the same broad pattern. While 48 of 343 mares born prior to 1985 produced superior runners by him, or 14%, only 28 of 453 (6.2%) born after 1984 did so. Of the 277 mares born after 1989, only 10 (3.6%) produced superior runners by him. Diesis got a superior runner from only one of 64 mares with Mr. Prospector in their ancestries, and he was barely in range of his average with mares in descent of Northern Dancer.

With each successive broodmare population cohort, in which crosses of Northern Dancer and Mr. Prospector assured a rapid accumulation of Native Dancer influence, the strike rates of Dixieland Band and Diesis declined. It seems warrantable to conclude that Native Dancer’s proliferation in the broodmare population had a more profound effect on their stud records than could possibly be attributed to a decline in viability due to increasing age.

Measuring Ancestor Appeal

by Roger Lyons

Recent posts about Dixieland Band and Graustark preceded their broader context, which arrives as a table, titled “Ancestor Preferences of Major US Sires.” The table covers 164 ancestors and reflects, among other things, how well or poorly individual ancestors of broodmares are playing to the contemporary stallion population. Links to three different versions of the table are provided below.

The table is very simple once you catch on to the concept. To over-simplify, there’s about a 31% chance that a stallion whose name you pick out of a hat is going to react well with Storm Cat in the ancestry of a mare and only about a 9% chance of an unfavorable reaction. That leaves about 60% that do okay with Storm Cat, but not many breeders dream of results that are okay.

If your mare is by Storm Cat, the odds are not bad that you’ll draw a suitable stallion by chance, at least in that respect. However, if her dam happens to be by Halo, with which only 13% of the stallion population react favorably against the 22% that react unfavorably, it’s more complicated. Thus do questions of compatibility arise from the layers of a mare’s ancestry.

Clearly, the breeding of some mares renders them far more flexible as to the selection of a mate than other mares. Ideally, you would want a stallion to have high stike rates with a mare’s entire ancestry. Some mares may have a range of such options, but for other mares there’s no such stallion.

Anyway, for each ancestor, I surveyed 71 proven sires to determine, first, how many of them sired foals out of at least 10 mares in some descent of the subject ancestor. Second, the qualifying sires were divided into two groups: 1) those that, from mares in some descent of the subject ancestor, had strike rates significantly above their overall records and 2) those that had significantly lower strike rates with those mares.

Here’s the legend for the resulting table:

Ancestor–the subject ancestor as represented by broodmares.
Sires–the number of stallions (from among the 71) that sired 10 or more foals with mares representing the ancestor.
Approve–the number from the “Sires” group with significantly higher-than-average strike rates.
Approve%–the percentage of “Sires” with significantly higher-than-average strike rates.
Disapprove–the number from the “Sires” group with significantly lower-than-average strike rates.
Disapprove%–the percentage of “Sires” with significantly lower-than-average strike rates.

There are three versions of the table, one listing 164 ancestors by “Approve%” rank to show them in order of the frequency of high strike rates by the stallion sample; another listing them by “Disapprove%” rank to reflect the downside risk; and then an alphabetical listing so you can have fun looking them up individually.

Bear in mind, the survey includes only US sires. Danzig’s approval rating of only 14% and disapproval rating of 23% would be vastly different based on a survey of European or Australasian sires. Nevertheless, Danzig is a problem for a lot of US stallions.

I’ll comment further on this table in future posts, beginning with the reason why Native Dancer’s approval rating is the lowest in the list.

Dixieland Band Delivers

by Roger Lyons

Dixieland Band ranked fifth among broodmare sires on 2010 earnings. Although that says a lot about the quality of his daughters, there’s a lot more to the story of his influence in the ancestries of producers. I can’t tell the whole story because, as anybody who reads this blog already knows, I’m not a horseman in any professional sense.

Sure, I love horses (who doesn’t?) and I’m around them every day, but that doesn’t qualify me to be an authority on exactly what it is Dixieland Band contributes through the dams of horses like Uncle Mo (Indian Charlie-Playa Maya, by Arch), whose second dam is by Dixieland Band. Yes, it’s mildly embarrassing that I’m just a numbers cruncher, but I can live with that as long as it enables me to report that something is happening, even if I can’t say exactly what it is.

So. It happens that Indian Charlie has sired foals out of only nine mares with Dixieland Band in their ancestries through his 2007 crop, and from those nine he got three superior runners, including Two Trail Sioux (G2), also out of a mare whose dam is by Dixieland Band. Uncle Mo (2008) is his fourth.

The bigger story is that Indian Charlie is not alone in having a very high strike rate with mares that have Dixieland Band in their ancestries. A survey of US sires for which I’ve kept comprehensive strike rates over the years turned up 29 that had sired foals out of at least 10 mares that had Dixieland Band in their ancestries, and 11 of those sires had superior-runner strike rates which, like that of Indian Charlie, significantly exceeded their overall records. Put another way, Dixieland Band has a 38% approval rating among contemporary sires.

But that’s not all. Dixieland Band’s disapproval rating is only 7% (55% having average strike rates). To put that in perspective, consider the record of Roberto, sire of Kris S., broodmare sire of Uncle Mo. Roberto has a 23% approval rating, which is still relatively high, but his disapproval rating is 24%. So, basically, if you pick a stallion at random, there’s a 23% chance that he’s going to manage Roberto’s influence quite favorably and a 24% chance that Roberto’s influence is going to be downright unfavorable. You can see by comparison with Roberto, then, that Dixieland Band’s influence through broodmares plays extremely well in the contemporary stallion population, with a very minimal downside risk.

As far as Indian Charlie is concerned, Roberto’s influence is innocuous from a statistical point of view, with a strike rate of 4/40 (Uncle Mo is the fifth superior runner). Yes, there are effects, no doubt, but they don’t pay off all that frequently for Indian Charlie. The numbers say Dixieland Band is probably the major player in the pedigree context of Uncle Mo’s dam, and they also say that Dixieland Band routinely contributes traits that, although quite possibly waning in the stallion population, remain highly exploitable by it.