The Jockey Club Releases 2021 Report of Mares Bred Statistics

The Jockey Club has released Report of Mares Bred (RMB) statistics for the 2021 breeding season. Based on RMBs received through October 18, 2021, The Jockey Club reports that 1,016 stallions covered 27,829 mares in North America during 2021.

The Jockey Club estimates an additional 2,500 to 3,500 mares will be reported as bred during the 2021 breeding season.

RMB statistics for all reported stallions in 2021 are available through the Fact Book section of The Jockey Club’s website at

Kentucky traditionally leads North America in Thoroughbred breeding activity. During 2021, Kentucky’s 200 reported stallions covered 16,727 mares, or 60.1% of all of the mares reported bred in North America. The number of mares bred to Kentucky stallions increased 2.0% percent compared with the 16,391 reported at this time last year.

Of the top 10 states and provinces by number of mares reported bred in 2021, stallions in Kentucky, California, Ontario, and Indiana covered more mares in 2021 than in 2020, as reported at this time last year. The following table shows the top 10 states and provinces ranked by number of mares reported bred in 2021:

State/Province 2020 Stallions 2021 Stallions Pct. Change 2020 Mares Bred 2021 Mares Bred Pct. Change
Kentucky 200 200 0% 16,391 16,727 2.0%
California 103 104 1.0% 1,766 1,843 4.4%
Florida 73 62 -15.1% 1,721 1,562 -9.2%
New York 37 38 2.7% 1,002 948 -5.4%
Louisiana 74 64 -13.5% 1,017 890 -12.5%
Maryland 29 25 -13.8% 806 778 -3.5%
Ontario 24 27 12.5% 519 591 13.9%
Pennsylvania 37 29 -21.6% 734 524 -28.6%
Indiana 42 45 7.1% 427 475 11.2%
Oklahoma 40 46 15.0% 476 441 -7.4%

Note: Each incident in which a mare was bred to more than one stallion and appeared on multiple RMBs is counted separately. As such, mares bred totals listed in the table above may differ slightly from counts of distinct mares bred.

In addition, Report of Mares Bred information on stallions that bred mares in North America is available through report 36P or a subscription service at

The Jockey Club, founded in 1894 and dedicated to the improvement of Thoroughbred breeding and racing, is the breed registry for North American Thoroughbreds. In fulfillment of its mission, The Jockey Club, directly or through subsidiaries, provides support and leadership on a wide range of important industry initiatives, and it serves the information and technology needs of owners, breeders, media, fans and farms. It founded America’s Best Racing (, the broad-based fan development initiative for Thoroughbred racing, and in partnership with the Thoroughbred Owners and Breeders Association, operates OwnerView (, the ownership resource. Additional information is available at

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