What happens to the mares?
Just before giving birth they are taken "off line" where they are allowed to foal in outside paddocks. When the foal is removed, mares are sent out to breed again. After successful breeding they are returned to the line.
If breeding is unsuccessful, the mares are sent to auction or slaughter.
The is Gulliver - A six year old stallion at Jumpin' jack Ranch. He is 6 years old now and greets the new foals that are fortunate to have been rescued with the mares. Again male foals and horses not deemed necessary in the production of urine are sent to auction or slaughter.