If any one person has had a positive influence on racing since we began the new century it is Jess Jackson.  I would go so far as to say that he is the number one racing fan in the United States. I say this because Mr. Jackson wants to see which horse is the true champion and he puts his money where his mouth is. Not many horseman would have run Rachel Alexandra in the Preakness Stakes and it is only through the efforts of Jess Jackson that we were able to witness this historic event. This comes on the heels of his courageous move of keeping Curlin in training as a four-year-old to prove he is a great champion. Curlin went on to become the leading money winning thoroughbred and greatly added to his stature, and helped the sport immeasureably. All sports need their hero's and Jess Jackson creates them by giving his horses a chance to prove their greatness.
With that being said, let me throw in a bit of controversy. Prior to the running of the Preakness Mr. Jackson said he would like to breed Rachel Alexandra to Curlin in the hope of getting a super horse, a horse better then either parent. Unfortunately, that would be the equivalent of trying to breed a tomato as big as a house. Horses like Curlin and Rachel Alexandra are the genetic limits of the breed. The fact is there aren't any better horses than they are. When bred to each other they will almost certainly breed down from their own racing indexes.
My research shows that only 3% of the champion horses in North America were produced by mares who were themselves champions. Of the 287 champions in this time period only 10 were produced by mares who were champions on the racecourse.
Figure 1
 Champion Dam          Racing Index                                                       Champion Offspring        Racing Index
 
  Two Lea                           1045                                                                             Tim Tam                                 1458
  Affectionately               676                                                                              Personality                             753
  Princess Turia              592                                                                              Forward Pass                         936
  Nellie Flag                        484                                                                              Mar-Kell                                    241
  Jacola                                  483                                                                              Phalanx                                     449
  Flower Bowl                    402                                                                             Bowl of flowers                   1514
  Big Hurry                          379                                                                              Bridal Flower                         357
  Myrtlewood                    378                                                                              Durazna                                    416
  Misty Morn                     331                                                                               Bold Lad                                   1133
  Now What                         310                                                                              Next Move                                724
 
Mares with indexes 400 or higher bred only 3% of the champions during the 42 year time period. It is around the index of 400 that the "law of diminishing returns" sets in. From that point on, as the racing index of the mare increases, her ability to produce horses of championship caliber decreases (except on grass). Remember, I said horses of championship caliber, not stakes winners. Mares with racing indexes of 400 or higher often breed stakes winners, but these stakes winners almost always have racing indexes markedly below that of their dams. When you approach this question of "class in the dam" without a racing index you may be misled by the fact that stakes winning mares produce a larger number of stakes winners than their own percentage of the breed. This can lead you to believe that the more racing class the better
 
Another trend that can be monitored by indexing is what happens when very high indexed mares breed up.  Nine of the ten mares in Figure 1 bred runners with indexes equal to or greater than their own. One, Nellie Flag produced Mar-Kell whose racing index was 1/2 of her own. Remember, Nellie Flag was the last filly to win the Preakness Stakes before Rachel Alexandra. The nine runners with racing indexes equal to or greater than their own were all disappointing stallions or producers except one, Next Move.
 
Tim Tam bred only one good horse, Tosmah. Forward Pass and Personality were dismal failures. Phalanx sired two good horses, Career Boy and Fisherman. Bold lad's best runner was Sirlad who ran a strong 2nd to Affirmed in the Hollywood Gold Cup but otherwise didn't sire much dispite great opportunity. Bridal Flower's best runner Beylerbey earned a 28 racing index. Durazna's best was Querida with an 82 index. Only Next Move bred really good horse when to the cover of Native Dancer she got Good Move index 627. The great Bowl of Flowers with an extremely high index of 1514 had a best runner named Spruce Bouquet with an index of 129 which is only 11% of her own index.
 
On the other hand Mar-Kell who had a racing index 50% of her dam's produced Mark-Ye-Well with a racing index of 742.......Three times her own.
 
Another interesting point is that Bowl of Flowers, although she bred down from her own very high racing index of 1514, produced two sons, who although poor racehorses, were very good stallions. The are Whisky Road and Big Burn. The former, a son of Nijinsky II stood in Australia where he sired Strawberry Road the winner of their most prestigious race, the Melbourne Cup. 
 
It appears that when high indexed mares breed up from their own indexes the resulting champions will be poor risks at stud. conversely, when champion mares breed down some of their foals make excellent breeding prospects.
 
No less an authority then Federico Tesio believed that hard racing drained a certain vitality that required a generation of rest to be restored. Tesio who harbored some very esoteric ideas, nevertheless bred two undefeated and unextrended colts in Nearco and Ribot with profound and lasting influence on the breed.
 
If you have any doubts about what type of racemares produce the highest quality racehorses here is a list of all of the Triple Crown winners except Sir Barton (unable to find his dams index) along with the other great racehorses of recent times.
 
Champion                                   racing index                                                        dam                                      racing index
 
- Man O" War                    1100                                                             Mahubah                                    15 
- Omaha                               700                                                             Flambino                                   99 
- War Admiral                 1190                                                              Brushup                                     15 
- Gallant Fox                    1650                                                             Marguerite                                 0 
- Assault                              875                                                              Igual                                            unr 
- Whirlaway                       886                                                               Dustwhirl                                  unr 
- Count Fleet            1096                                             Quickly                            58 
- Citation                   1655                                             Hydroplane II                unr 
- Secretariat             1909                                             Somethingroyal               0 
- Seattle Slew           1877                                              My Charmer                   45 
- Affirmed                 2416                                             Won't Tell You                56 
- Native Dancer        1608                                             Geisha                             24 
- Nashua                    1956                                             Segula                              59 
- Spectacular Bid      1844                                             Spectacular                     66 
- John Henry            1581                                              Once Double                     8 
- Dr. Fager                1785                                              Aspidistra                        24 
- Forego                     1135                                             Lady Golconda                99 
- Round Table           1292                                             Knights Daughter           79 
- Swaps                       1566                                            Iron Reward                      3 
- Buckpasser              1869                                            Busanda                         247 
- Tom fool                   953                                              Gaga                                 51 
- Kelso                         1822                                             Maid of flight                  81 
- Seabiscuit                  499                                             Swing On                       unr    
None of the dams of these superlative racehorses was a champion. A rule of thumb would be that champion racehorses, with a few exceptions, have racing indexes of 400 or higher. Only one of these dams of champions had a racing index over 100 that being Busanda the dam of Buckpasser. Busanda achieved her high index by winning the 1951 renewal of the Suburban Handicap while carring only 102 pounds.
 
The Dilemma facing Jess Jackson is how to breed Rachel Alexandra to achieve the best results. In all likelihood it will be her daughters and granddaughters that will be the great producers not Rachel Alexandra herself. The answer may be found in the production record of Myrtlewood. She was a champion with a 378 racing index (low index probably because she raced during the depression when stakes horses ran in allowance races with low purses). Myrtlewood produced Durazna whose racing index was 416 just about the same as her dam. Regression did not set in because Durazna was by Bull Lea the leading sire in North America one of the few stallions I've seen that could overcome regression. In figure 1 four of the horses mentioned were by Bull Lea. They are Two Lea, Durazna, Next Move and Mark-Ye Well. Yet inspite of his ability to breed fast mares up, all of Bull Lea's sons failed at stud including Citation and Coaltown. So, although Durazna had a racing index equal to her dams, and although she was by the exceptional broodmare sire Bull Lea, her best runner had an index of 98.
 
Here is one last caveat concerning "Class in the Dam" . Mares that are champions on Turf are much more likely to produce champions then their counterparts that race on dirt. Why? It could be that grass is a much more natural surface and doesn't drain the horse of vitality to run over it. The trainer of the 2nd horse I bred was Miguel Clement who had trained two winners of the Prix du Jockey Club (French Derby). He told me that we Americans breed 20 Sea-Birds every year, but only one survives our training methods. That may be the reason.
 
An example of a top grass mare that is an exceptional producer is Urban Sea. She is herself the winner of the Prix de l'arc de Triomphe yet she is the dam of this year's Epsom Derby winner Sea the Stars, another Epsom Derby winner in Galileo, the Italian Derby winner Black Sam Bellamy, and the brilliant grade one winner in North America, My Typhoon.
 
Every week on this blog I will analyze the grade one and grade two winners from the previous week with special attention to the correlation between the winners racing index and their dams. Your comments will make for a lively discussion