Report of Mares Bred: Declines in Stallions, Breeding

The Jockey Club Report of Mares Bred statistics for the 2018 breeding season shows declines in stallions and breeding activity.

Based on RMBs received through Oct. 16, The Jockey Club reports that 1,214 stallions covered 30,274 mares in North America during 2018. The number of stallions declined 9.5% from the 1,342 reported at this time in 2017, and the number of mares bred decreased 5% from the 31,863 reported last year.

The Jockey Club estimates an additional 3,000 to 4,000 mares will be reported as bred during the 2018 breeding season.

The number of stallions covering 125 or more mares increased from 60 in 2017 to 62 in 2018. 

* Statistics summarized as of Oct. 16 of the breeding seasons indicated in the columns above; as reports of mares bred continue to be received, final statistics are subject to change.

Further book size analysis shows a 3% increase in the number of mares bred to stallions with a book size of 125 or more in 2018 when compared with 2017 as reported at this time last year; a 1.4% decrease in mares bred to stallions with a book size of 100-124; a 7% increase in mares bred to stallions with a book size of 75-99; a 6.7% decrease in mares bred to stallions with a book size of 50-74; a 9.6% decrease in mares bred to stallions with a book size of 25-49; and a 16.7% decrease in mares bred to stallions with a book size fewer than 25.

The percentage of broodmares covered by large book size (125 or more) stallions increased from 29.4% in 2017 to 31.9% in 2018. From 2015-17, this percentage had remained constant at approximately 29%, up from 20.5% in 2014.

The proportion of stallions with book sizes of 125 or more mares grew from 3.1% in 2014 to 4.5% from 2015-17. In 2018, this proportion increased to 5.1%.

RMB statistics for all reported stallions in 2018 are available through the Fact Book section of The Jockey Club's website at jockeyclub.com.

Into Mischief  led all stallions with 245 mares bred in 2018. Rounding out the top five by number of RMBs were Cupid , 223; Klimt , 222; Practical Joke , 220; and, Violence , 214.

Kentucky traditionally leads North America in Thoroughbred breeding activity. During 2018, Kentucky's 228 reported stallions covered 17,322 mares, or 57.2% of all of the mares reported bred in North America. The number of mares bred to Kentucky stallions increased 0.3% percent compared with the 17,275 reported at this time last year.

Of the top 10 states and provinces by number of mares reported bred in 2018, Kentucky, California, Maryland, and Pennsylvania stallions covered more mares in 2018 than in 2017, as reported at this time last year. Ontario, New York, and Oklahoma all saw double-digit percentage declines.

The following table shows the top 10 states and provinces ranked by number of mares reported bred in 2018:

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 equineline.com/ReportOfMaresBred.