Skip to main content

When studying a pedigree, we look at the sire record for the stallion and a produce record for the mare for analysis. It seems obvious that we need good stallions and mares to produce good foals, but many have come to realize the significance of a quality mare and the broodmare sire effect in the production of a foal.

Many breeders even feel the mare is anywhere from 60 to 100% responsible for producing a superior foal. But, is there a genetic basis for a mare’s increased influence in her foals?

Genetically speaking, we say the stallion and mare each contribute 50% to the foal. That can be true when looking at a filly produced by the mare; however, when we look at a mare’s sons, the balance is upset because of the X and Y chromosomes.

While a mare inherits X chromosomes from both her parents, a stallion inherits his Y from his sire and an X from his dam. Genetic research has found that the X chromosome a stallion inherits from his dam has more genetic information than the Y chromosome he inherited from his sire. Thus, the mare contributes more genes to the sons she produces.

There is an added genetic basis for a mare’s influence through her sons that should be considered when looking at a pedigree. Some stallions become known as successful broodmare sires for their outstanding daughters. This is called the “broodmare sire effect.” The basis of this effect comes when he passes the X he inherited from his dam to his daughters. This gives the foal a direct link to the sire’s dam. If a filly is produced, she will inherit an X from her sire and an X from her dam.

One stipulation that does exist is that one X may be dominant over the other X, allowing the dominant X to express its genetic information and hide the other X. But the hidden X can still have an influence in the next generation when it is passed to the mare’s foals, and then becomes a dominant X chromosome.

Broodmare Sire Effect: Here Comes The Boon

When Here Comes The Boon and Lance Johnson won the 50th National Reined Cow Horse Association (NRCHA) Snaffle Bit Futurity Open Championship, the sport’s biggest fans went crazy. The duo also won Futurity Intermediate Open in a fairy-tale finish.

The 2016 bay roan stallion (Once In A Blu Boon x Stay Outta My Shorts x Shorty Lena) was bred by Randy and Sharon Butler, and he is owned by Brent Steward’s Rocking BS Ranch. He closed out 2019 with $205,564 garnered in two shows — the first of which being the National Stock Horse Association Futurity, where they also won the Futurity Open and Intermediate Open.

Here Comes The Boon’s sire, Once In A Blu Boon (Peptoboonsmal x Autumn Boon x Dual Pep), is the winner of $316,564 and an Equi-Stat Elite $1 Million Sire. Equi-Stat Elite $27 Million Sire Peptoboonsmal (Peppy San Badger x Royal Blue Boon x Boon Bar) was the 1995 National Cutting Horse Association Futurity Open Champion, and Royal Blue Boon is the all-time leading dam of cutting money-winners, with earnings of more than $2.6 million recorded in Equi-Stat. Her top performer is Red White And Boon, the No. 1 cutting horse of all time with more than $922,000 won.

Autumn Boon is also out of Royal Blue Boon. Her foals have amassed $1.95 million, with only Equi-Stat Elite $5 Million Sire Im Countin Checks ahead of Once In A Blu Boon on her progeny record. This gives Once In A Blu Boon a breeding pattern of 2 X 2 to Royal Blue Boon, making Boon Bar the broodmare sire of both Peptoboonsmal and Autumn Boon.

Stay Outta My Shorts (Shorty Lena x Oaklynn x Doc’s Oak) carries a lot of the same blood as Once In A Blu Boon, though less intense. Shorty Lena is a son of Doc O’Lena, by Doc Bar. Oaklynn (out of Go Go Princess x Royal Poco Dell) is a daughter of the Doc’s Oak, by Doc Bar. She is the winner of $47,380 and the dam of horses that have won $442,192, including 2000 NRCHA World’s Greatest Horseman Champion Paid By Chic.

Boon Bar, with $6,896,537 as a broodmare sire; Dual Pep, with $35,842,608; Shorty Lena, with $16,573,144; and Doc’s Oak, with $16,754,764, are all stallions whose daughters have made a significant contribution to the foals they produced. They are all also in Here Come The Boon’s pedigree.

This means Here Comes The Boon’s bloodlines give us some insight into how stallions can influence the female side of the pedigree. It also shows us the genetic basis of the “magic cross” and the link between the broodmare sire and his daughters in that cross.


Quarter Horse News
written by Larry Thornton
View article on QHN

Rocking BS Ranch
Brent & Suzie Steward
Las Vegas, NV

T: (702) 498-3810