Check with your veterinarian first, because in almost all cases, your mare will need to be ultrasounded every 12 hours to determine the best time to inseminate frozen semen. Timing is more critical than with cooled shipped semen. I think very few don't graduate because they are carefully chosen for the school. Some are eliminated because they get too big to match the other horses in the school. They are sold to or go back to Piber for breeding services.
Andalusian horses are, of course, Spanish horses.
I suppose you could say the Andalusians are the ancestors of the Lipizzans. My grandson thanks you a lot. He raised the question because he went to a lippizan horse show in Quebec, a gift from his father. That's a good question. The answer is approximately 1800.