Rasmussen Factor, Degree of Inbreeding

Today we will examine the Rasmussen Factor using these sales foals of 2003-2007 with regard to degree of inbreeding. Are closer duplication better than more distant duplications or vice versa??????

First of all, you need to define and name your groups. I choose to call group six all nags with duplications of 3×3, 4×2 or converses, or closer. Some 2×3 and converses did show up but nothing closer than that.

Group seven is comprised of 3×4 and converses. Some 2×5 and converses also showed up.

Group eight is comprised of 4×4 and 3×5 and converses. Group nine is comprised of 4×5 and converses. Group Ten is comprised of 5×5.

The foregoing suffices for nags with only two duplications. Some nags have more than two duplications of the same female ancestor though. And some nags have more than one female ancestor duplicated within five generations.

An example of the former is the stakes winner Jeremy (5x5x5 to Natalma). An example of the latter is the stakes winner Malibu Mint (5×5 to both Somethingroyal and Raise You). I call this group multiples and will deal with them later.

Table 1

Prices by Degree of Inbreeding

Degree of Inbreeding      Foals      Average          Maverage          Price Index

Seven or Closer                508        $59,883            161.85                    0.99

Eight                                  679          55,836             158.36                    0.97

Nine                                   1,338       57,303             166.78                   1.02

Ten                                    2,118        64,177              182.67                   1.12

Multiples                           467          72,474              179.63                   1.10

Totals                                5,110       61,600             172.93                   1.06

I chose to list multiples after the ten group because multiple duplications tend to be farther back in pedigrees than other duplications. I chose to combine seven and six or closer because the latter is so small (only 180 foals, 328 foals for the former).

The overall trend of these price data is pretty clear. The numbers generally (though not always) rise from seven or closer to multiples. Seven or closer ($59,883) is higher than eight ($55,836), but nine ($57,303) is higher than eight, ten ($64,177) is higher than nine, and multiples ($72,474) are higher than ten.

Maverages follow the same overall pattern. Seven or closer (161.85) is higher than eight (158.36), but nine (166.78) is higher than eight (and seven or closer). Ten (182.67) is higher than nine, but multiples (179.63) are lower than ten. Price Indexes mirror the maverages.

Do the racing results follow the same pattern???? The answer is in Table 2.

Table 2

PPIs (Results) by Degree of Inbreeding

Degree of Inbreeding     Foals      SWs       %      PPPSW      PPI (Result)

Seven or closer                 508        14        2.76     439                 0.60

Eight                                  679         19        2.80     517                 0.72

Nine                                 1,338        41        3.06     648                0.98

Ten                                   2,118       80        3.78      531                0.99

Multiples                             467      16         3.43       612               1.04

Totals                               5,110     170        3.33       558               0.92

SWS stands for stakes winners. PPPSW stands for Performance Points per stakes winner. The percentage of stakes winners from foals rises from 2.75 for seven or closer to 2.80 for eight to 3.06 for nine to 3.78 for ten, then falls off to 3.43 for multiples. The overall percentage is 3.33, compared to 3.36 for all 2,373 stakes winners from 70,714 foals. Percentage of stakes winners from foals measures the QUANTITY of the stakes winners.

Performance Points per stakes winner measures the QUALITY of the stakes winners. It rises from 439 for seven or closer to 517 for eight and peaks at 648 for nine. Ten is lower at 531, but multiples are higher at 612. The overall average for the 170 RF stakes winners is 558, compared to the overall average for all 2,373 stakes winners of 603.

(Round Pond was by far the best of these 170 RF stakes winners, with 3,399 Performance Points. She falls into the nine group and helps its results a lot. Without Round Pond, the average Performance Points per stakes winner for that group falls from 648 to 580.)

PPI (results) takes both quantity and quality into account and combines them into one number. It rises from 0.60 for seven or closer to 0.72 for eight to 0.98 for nine (0.86 without Round Pond) to 0.99 for ten to 1.04 for multiples.

It is rare to see statistics line up so neatly. Seven and closer and eight are well below the overall results for all 5,110 RF foals (0.92). Eight, nine, and multiples are above 0.92. Only multiples are above 1.00 (the overall average for all 70,714 foals).

Most people think that inbreeding is a good thing and that the closer you duplicate, the better the results. Table 2 shows exactly the opposite. Not too surprising, if you consider that RF inbreeding was NOT a good thing overall (results of 0.92, compared to  the average of 1.00).

If a particular scheme is generally NOT a good thing, then it stands to reason that the less closely you have it, the better the results will be, and the more closely you have it, the worse the results will be.

So perhaps people need to rethink the theory that inbreeding is a good thing, and the closer it is, the better it is. In this particular case at least, inbreeding is NOT a good thing, and the less closely you have it, the better the results are.

Better, though still not particularly good (above 1.00), except for multiples. And even multiples, with a PPI (result) of 1.04, did not exceed their Price Index (1.10). That is NOT particularly good value for the money.

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