One of the many fascinations of the thoroughbred is the way some stallions have a propensity to supply more stakes horses from one or other gender group. This has always been the case.
In the period covering the history of the European Pattern, there have been some outstanding sires of fillies. One of the early ones was Habitat, who delivered top-class fillies such as Marwell, Habibti, Flying Water, Rose Bowl, Sigy and Brocade. As a group they left the distinct impression that Habitat was a fillies’ sire and that fact is hard to counter given that his best colts and geldings were never in the same league.
Here’s the thing though: Habitat sired 27 Group-winning colts and 26 Group-winning fillies, so there is no statistical bias in favour of his fillies. This calls into question how we measure a gender bias and suggests that careful consideration should be given to both quality of runner as well as any numerical advantage.
There is a fascinating battle being played out at present among two sires at the opposite end of the gender bias scale. Whereas Night Of Thunder is more likely to get a black-type filly, Wootton Bassett overwhelmingly conducts his black-type business through his sons. In fact, among all active sires, these two are respectively showing the most bias in favour of a specific gender, with Night Of Thunder’s female stakes-horse percentage (24 per cent) almost nine percentage points clear of his male runners’ total (15.1 per cent). Wootton Bassett, meanwhile, has a wider gap in favour of his male runners, which feature 21.5 per cent stakes horses compared to his fillies’ 9.6 per cent.
The metrics above may present a very clear picture, but it cannot be positively employed when planning matings for the vast majority of breeders. It is far more valuable for buyers of youngstock who at least have all the facts before them when making purchasing decisions. That said, there is always more complexity to any metric and when it comes to gender bias, the complexity usually
arrives in the shape of a very talented outlier.
Until the end of last season, Night Of Thunder had not sired a Group 1- winning male runner. Now he has two with another, in the shape of the William Haggas-trained Group 2 Hungerford Stakes winner More Thunder (Timeform 120p), perhaps already good enough to become a third top-flight scorer for his sire this year. I guess it would be very hard to convince Haggas to go easy on male yearlings by Night Of Thunder at the forthcoming yearling sales as he also has Irish Champion Stakes winner Economics in his care.
As things stand, Ombudsman (Timeform 130) and Economics (Timeform 126) are Night Of Thunder’s most accomplished Group 1 winners. The existence of these two colts might be enough for some to forego the stats on Night Of Thunder’s male runners but always remember that it is extremely difficult to earn black-type in the first place and that you are more likely to get an ordinary stakes horse long before you get a Group 1 winner, so the metrics still stand and should not be ignored.
It can also be noted here that Night Of Thunder has an inbuilt advantage in that the current black-type structure in these parts favours fillies. For instance, we know that in many sectors of racing a filly is twice as likely to earn black type as an identically rated colt.
Given that fillies have this inbuilt advantage, should we give even more credit to Wootton Bassett? He too has his talented exceptions, none more so than this year’s dual Group 1 scorer Whirl, her sire’s best filly so far with a 122 Timeform mark. The Pretty Polly-Nassau Stakes heroine follows Audarya and Zellie as the third female Group 1 winner for Wootton Bassett, who has 15 male top- flight winners.
Like Night Of Thunder, Siyouni’s stakes fillies outscore their male counterparts, in his case by a score of 20.3 per cent to 12.7 per cent. Zarigana (Timeform 115) is the latest in a long
line of Group 1-winning fillies, which now number seven among Siyouni’s total of ten. The likes of Laurens, Mqse De Sevigne, Ervedya and Tahiyra (all rated 120 by Timeform) set the standard for Siyouni fillies, but again it is his three Group 1-winning colts St Mark’s Basilica (Timeform 132), Paddington (128) and Sottsass (127) that top his progeny ratings.
Interestingly, Siyouni’s sire Pivotal also showed a filly and mare bias, siring 94 (13.6 per cent) stakes-winning fillies and 59 (8.4 per cent) stakes winning colts.
The greater opportunities afforded to fillies inevitably means that almost twice as many sires show a slight bias in favour of stakes fillies in their raw data, so the difference needs to be fairly substantial to be classed as significant.
Two major stallions that could be classed a better sire of fillies than colts at least by some metrics are Dubawi and Frankel. The difference between their filly and colt stakes horse output is 4.7 and 4.6 percentage points respectively, but it is hard to argue that case given that Dubawi has 37 male Group/Grade 1 winners and 14 filly Group/Grade 1 scorers. Frankel, meanwhile, has an even spread of 17 Group 1-winning fillies and 18 top-flight colts.
For the record, it is Frankel who leads all metrics relating to fillies, with 28.9 stakes horses, 20.6 stakes winners, 12.8 per cent Group winners and 4.4 per cent Group 1 winners, followed by Dubawi and Night Of Thunder. And it is Dubawi who heads most of the colt categories.
Back to the other end of the scale, we have another Dubawi in New Bay next behind Wootton Bassett with the biggest gulf in favour of his colts and geldings. The Ballylinch Stud stallion has sired 32 (15.2 per cent) male stakes horses and only 11 (5.9 per cent) filly/ mare stakes horses. That trend continues through New Bay’s stakes winners, with 16 male and four female, and also Group winners, with 14 colts versus just a single filly. That filly is none other than Saffron Beach, rated 121 by Timeform and one of New Bay’s tally of three Group/Grade 1 winners.
