Will capping number of mares bred by stallions improve thorougbreds?

Last week the Jockey club proposed putting a cap on the number of mares an individual stallion can cover in a season. The reasoning? To improve the genetic diversity of the thoroughbred breed.

A press release from the Jockey Club noted, “43 stallions reporting 140 or more mares” in their 2018 books, and those stallions accounted for nearly 30 percent of

Into Mischief is the leading sire in the US, covering 245 mares in 2018 and commanding a stud fee of $150,000 per live birth.

the mares covered. The number of mares being bred has dropped from 63,479 in 1991 to 30,274 in 2018 and the number of active stallions has dropped from 6,696 in 1991 to 1,214 in 2018 [source: Thoroughbred Daily News]. So, you have fewer stallions covering fewer mares with the top 40 stallions covering more than 140 mares per year. Five stallions covered more than 200 mares: Into Mischief (245), Cupid (223), Klimt (222); Practical Joke (220); and Violence (214).

Compare this breeding approac h to the “old days.”  In the 1960s, a book of 36 mares was considered “full”. It crept up to 40 to 50 in the 1970s then exploded in the 80s and 90s to 150 to 160 mares.

Stud fees
The 2019 leading sires in North America, along with their stud fees.

Capping the number of mares that stallions can cover will impact only a small percentage of stallions, but for those already at the top of the list, the increase in stud fees may be significant. Take Into Mischief — demand for him as a sire far exceeds the 245 mares he covered in 2018, even at a fee of $150K per live birth. In turn, the foals from these elite stallions should also increase in value. Take the Curlin colt who sold at the 2019 Keeneland September sale for a staggering $4.1 million. Imagine what he’d be worth when breedings are capped!

The proposed capping scheme would be phased in over several years:

  • Stallions entering stud service for the first time in 2020 would be exempt from the 140 limit through the 2023 season;
  • Stallions that entered stud service in 2019 would be exempt through the 2022 season;
  • Stallions that entered stud service in 2018 would be exempt through the 2021 season;
  • Stallions that entered service in 2017 or prior would be subject to the 140 cap as of January 1, 2021.

Do you think that diversifying the breeding pool will help American Thoroughbreds? or have decades of breeding for speed over endurance be too much to overcome?

2 thoughts on “Will capping number of mares bred by stallions improve thorougbreds?

  1. I’ve been away from the TB industry too long. 140 mares in a single season???? HOw is that possible? Did the Jockey club break down under pressure and allow AI? Because, when I was working at a QH breeding farm (as a kid), the stallion was breeding 80 mares a year, but in reality, only physically covering perhaps half that many…the rest of the mares were served via collected semen and AI.
    140 or more…that’s too many mares. I think capping a book to the way it used to be, 30 or so, was the wisest course. It kept..maybe too well…some horses at the top of the heap who didn’t deserve it, but still.
    The biologist that I am is of the feeling that using a stallion too much depletes the quality of the semen. In the wild, a stallion would never have served that many mares. And, in the wild, he serves a single mare more than once.
    I think its a great idea to cap a stallion’s book, but not that high a number. That’s just greed, baby, greed, which is what has pretty much decimated the industry as a whole in the first place.
    Honestly, if the TB breeders really, really wanted to improve the genetic diversity of the breed as a whole, they’d shun Northern Dancer blood. The breeders have bred themselves into a genetic bottleneck by breeding solely for N. Dancer’s ‘speed gene’. I would bet my boots there’s not a stallion in the US right now that doesn’t have some ND blood. Understanding that, by the time one gets to one’s great grandparents, that genetic makeup is fairly well diluted, but still.
    Years ago I was massaging horses at a polo barn in Texas. A cohort of five or six solid built dark bay horses had been brought in from Argentina. They were SOLID, with good bone. I asked, what breed are they? and was astonished to learn they were all purebred TB’s. All of them. They weren’t bred for racing…they’d been bred for RIDING. And looked it.
    If the TB breeders in this country were thinking biologically and genetically, rather than how fast can this baby go, they would breed to those solid Argentinean horses. They might not win races, but they’d definitely add a lot of fresh blood, bone, and stamina.
    But I might as well keep wishing for Santa to bring me that damned pony, because the TB breeders, these days, aren’t in it for love. They’re in if for the money.

    1. It’s pretty distressing to see how TBs are now bred for early speed (by which I mean young) with no thought to endurance. Horses like Secretariat or Whirlaway had long careers. Now, if a horse is successful it’s often retired, especially if a stallion, at three and put to stud. There are many people who think that Justify was retired because he just couldn’t stand up to the rigors of racing, yet he’s standing for $150K per live foal. If he truly was lame after the Triple Crown, that doesn’t bode well for future generations. And his breeding rights were sold for $60 Million!!!

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