General Stud Book
The new rule was not applied retroactively, therefore all American-bred horses registered before 1913 remained on the register, and their descendants were also eligible for registration. Of the 7,756 mares in Volume 27 of the "General Stud Book", published in 1933, 930 would have been ineligible under the new rule. The Jersey Act did have an immediate impact however, as the winner of the 1914 Epsom Derby, Durbar II, was ineligible for registration, as his dam, Armenia, was bred in the United States and was not herself eligible for the "General Stud Book".