Easy to see why book-size cap would be bad news for sires like Into Mischief

The American Jockey Club’s controversial proposed cap on stallion book size remains a hot topic in the US. In an announcement made on the eve of the Keeneland September Sale, the Jockey Club stated it was considering limiting stallion-book size to 140 mares in response to concerns of the reduced "diversity of the thoroughbred gene pool".

Needless to say, those farms associated with breeding hefty numbers are not amused. On the other hand, several major names have come out in agreement that the situation is out of hand and needs addressing. Neither side are short of a vocal opinion or two.

Jockey Club figures show that 44 stallions covered 140 mares or more in 2019, compared to 24 in 2010. Coolmore’s unproven duo of Justify and Mendelssohn lead the way with 252 mares apiece, but a familiar name lurks not far behind in Spendthrift Farm’s Into Mischief, whose 2019 book checked in at 241 mares off a fee of $150,000.