The annual statistical ball of wax regarding the matings of stallions and mares has just been released by the Jockey Club, and the gross totals show that 227 stallions in Kentucky covered 17,750 (52.6 percent of all mares reported bred in North America), with an average book of slightly more than 78 mares.

By way of comparison, in 1991, 499 stallions stood in Kentucky and covered 14,595 mares, for an average book of slightly more than 29 mares.

Clearly, stallions should unionize.

In the last quarter-century, more than half of the Kentucky stallion pool (55 percent) has been sent packing at the same time that the mare pool has risen by almost 22 percent.

“Now just how does that work?” your unemployed stallion on the picket line might ask.

The change in the statistics is due to the evolution of broodmare and stallion management and the resulting escalation of book size that has been possible because of improvements or efficiencies in breeding management.

And, the opportunity to breed more mares to stallions has allowed enterprising stallion owners to pay more for stallion prospects. Therefore, any other farm wanting to compete with the farm that is using big books either has to adopt a larger book for its stallions or to step outside the mainstream of competition to acquire stallion prospects.

As a result, we have fewer and fewer farms standing fewer and fewer total stallions, yet breeding more and more mares.

And the answer to our unemployed stallion’s question above is that the fewer, super-select and commercially viable stallions used in Kentucky are breeding many more mares.

In fact, many popular young stallions will cover more mares before they ever have a runner than most top-tier stallions in preceding decades covered in their entire stallion careers.

Here are some stats from stallions of the past, per data from Equineline:

Stallion (year of birth)    foals      starters (%)        winners (%)        SW (%)

Nasrullah (1940)              426        378 (89)              290 (68)              98 (23)

Native Dancer (1950)     306        251 (82)              212 (69)              43 (14)

Bold Ruler (1954)            366        285 (78)              240 (66)              82 (22)

Hail to Reason (1958)     319        272 (85)              218 (68)              43 (13)

Northern Dancer (1961) 646        511 (79)              411 (64)              147 (23)

Raise a Native (1961)     863        585 (68)              434 (50)              77 (9)

Nijinsky (1967)                 862        686 (80)              519 (60)              156 (18)

Mr. Prospector (1970)    1195      986 (83)              755 (63)              182 (15)

The first stallion to pass 1,000 foals was Mr. Prospector, whose total was significantly due to his longevity and exceptional vitality and fertility. The bay stallion lived to be 29 and was active through the 1999 breeding season.

Yet, the top four covering stallions this year – yes, just the top four – were bred to a total of 880 mares. That number is larger than the total foals of every stallion on the foregoing list, except Mr. P.

[*Caveat for the devoted reader: I’m comparing red grapes and white grapes here, using total foals in comparison to total mares covered because lifetime stats do not include number of mares, just number of foals.]

The leader of this year’s covering stallions, and there’s no surprise, is Uncle Mo (by Indian Charlie), who was the leading freshman sire in 2015 by a wide margin. The unbeaten juvenile champion of 2010 was mighty popular before that, and after his first-crop racers did so well and included the Eclipse Award winner for best 2-year-old colt (Nyquist), he was a stallion manager’s dream.

Big, good-looking, and sure with his mares, Uncle Mo also stood at Ashford, whose other wildly popular young stallion, Scat Daddy (Johannesburg), died late last year. Presumably, Uncle Mo picked up a few extra mares from that sad situation. But Uncle Mo was breeding very large books of mares from the start of his stud career. Counting his four crops of live foals in Kentucky, Uncle Mo has sired 452 foals, with 261 foals of racing age in North America from his first two crops, now age 2 and 3, plus 126 yearlings and 65 weanlings.

In 2016, Uncle Mo covered 253 mares, and the other three stallions with more than 200 mares bred were Into Mischief (Harlan’s Holiday) 218, American Pharoah (Pioneerof the Nile) 208, and Kitten’s Joy (El Prado) 201.

The next half-dozen stallions on the list covered more than 175 mares each: Goldencents (Into Mischief) 190, Verrazano (More Than Ready) 190, Wicked Strong (Hard Spun) 190, Munnings (Speightstown) 182, Archarcharch (Arch) 176, and Tapiture (Tapit) 176.

These top 10 covering sires of 2016 were bred to 1,984 mares. They covered 11.2 percent of the total mare pool bred in Kentucky this year.

Two important conclusions can be drawn from this quick look at the top end of the stallion market. One is that while “some is good, more may not be better,” because as availability increases, prices per horse will inevitably decrease.

The second point is that a large portion of the breed, in the form of many of its most promising producers, are being mortgaged on the promise of success from young and unproven sires. The latter stallions fail more often than they succeed, and this cannot be a benefit to the breed.