The rule limiting stallions born from 2020 onwards from breeding more than 140 mares was adopted in May 2020 amid concerns around the narrowing of the diversity of the Thoroughbred gene pool in the US.
The Jockey Club announced today that it is rescinding the following italicized language in Rule 14C of The Jockey Club’s Principal Rules and Requirements of the American Studbook that addresses limitations to the total number of mares bred per stallion:The total number of broodmares bred per individual stallion whose year of birth is 2020 or thereafter shall not exceed 140 per calendar year in the United States, Canada, and Puerto Rico. The Jockey Club shall limit the number of Stallion Service Certificates for such stallions to a maximum of 140 per calendar year.