The Important Life of a Broodmare

Updated: Jan 13



A few years ago, a study was conducted on the influence the dam has on her offspring. The paper that went along with the study, “Potential role of maternal lineage in the Thoroughbred breeding strategy”, was published in Reproduction, Fertility and Development in May 2015, by Xiang Lin. BloodHorse summarized the conclusion of the study with, “The researchers hypothesize that this is due to mitochondrial DNA (mtDNA), which is inherited only through the female parent and has a strong influence in the production of ATP, the prime source of energy for any activity, in particular, physical exercise”. With this in mind, it is unfortunate that the general public knows very little about the life of broodmares and the importance they have in the Thoroughbred industry. I decided to take things in my own hands and talk to someone who has experience with broodmares and their foals. Candace Johnson has been around horses for years and currently owns about twenty broodmares. She also has racehorses, yearlings, and foals. She is thoroughly involved the Thoroughbred horse racing industry through KC Stables.

How do breeders Know Who Will Be A successful broodmare?:


If broodmares are more important than sires, it is very important to choose a good broodmare prospect. Johnson said that there are many things she looks for when choosing a broodmare, though she notes that each breeder has their own preferences. Johnson considers height, build conformation, and clean legs. She also analyzes the bloodlines and bloodline production. For example, she looks to see if the 1st dam has produced winners and what the sire of her broodmare prospect accomplished.

Thoroughbred Owner Breeder, a UK publication, reported that the mares who produced the largest percentage of Grade 1 or Group 1 winners were winners at that level themselves. The report also noted that “while the Graded/Group-winning mares were the most reliable sources of top-class winners, they were responsible for only 238 of the 1,366 Group/Grade 1 winners produced by the mares in the study”. Video: Nine-Time Gr.1 winner Songbird sells for $9.5 million as a broodmare prospect.


The numbers show a better chance of producing a Grade 1 winner if the mare is a graded winner herself, but it does not always work out that way. Zenyatta was a top-performing racehorse but has failed so far to produce a graded stakes winning foal. Littleprincessemma, on the other hand, never even broke her maiden and she produced Triple Crown champion American Pharoah. Serena’s Song, however, was a sensational racehorse and carried her success into motherhood. Many incredible racehorses are her descendants.


Similarly to other aspects of horse racing, finding a broodmare who will produce graded-stakes winning foals can be a gamble.


The Life of a Broodmare:


If a mare is tested on the track before becoming a broodmare, she must make the transition from life at the racetrack to life in the paddock. “The transformation to me is quite simple,” Johnson said. “I pull her shoes and turn her out with other mares to just be a horse for awhile”. Once a horse has adjusted to life on a farm, her fertility levels are tested and tracked. “Once breeding season comes along we check fertile dates and follicle size to find the prime day(s) for breeding,” explained Johnson. “Once she is confirmed at her prime, we make arrangements for the breeding shed with the stallion of our choosing”. Even though a mare is thought to have more of an influence on the ability of a potential racehorse, choosing stallions is still very important. Many breeders match mares and stallions that will, hopefully, balance each other out. “Perhaps my broodmare is smaller in frame, I would look for a taller stallion to breed her with,” Johnson described. “Maybe my broodmare has good breeding on her sire side but lacks something on 1st dam side, I would try to match up there as well”.

“You can go straight for bloodlines and pay a stud fee of up to $500,000, but there is no guarantee that the hypothetical foal will turn out to be what most race horse people are after - a triple crown winner,” said Johnson. “Then you could pay a stud fee of $500 and perhaps take the triple crown. It’s a gamble”. Once a mare is bred, Johnson turns her out for anywhere from 12 to 20 days. Then, the mare is given an ultrasound to confirm the pregnancy and to give an approximate due date. Then, the mare is cared for as usual until it is time for her to give birth. The mare will be pregnant for around 11 months, though some will give birth sooner and some later. Giving birth is a process too. “Once she foals, mom and baby are checked to make sure placenta has passed,” explained Johnson. “Baby will receive a enema to assure the foal passes the meconium and [we will] apply iodine to its umbilicus”.

Video: Zenyatta tending to her newborn 2014 filly. This filly tragically passed in a paddock accident about 6 months later.


It is essential that a mare and her foal bond, so Johnson keeps hers together in a stall for two weeks. This time also allows the foal’s legs to grow stronger. Afterwards, they are turned out into the pasture. This, Johnson says, is the most entertaining part. “I love to see the foal get ahold of their new legs in a bigger place. They run, buck, rear, and drive their mom crazy. It’s a beautiful site!”. A mare can have anywhere from 1 to 10 foals and it can take a few foals before a mare really shows her ability as a producer.


The amount of foals a mare has is dependent on both the mare and the people who own her. After a mare has proven unsuccessful at producing or becomes high up in age, the mare will be pensioned (retired). She will then move on to a new lifestyle. Pensioned broodmares can become anything from trail horses to eventers. Other times, they are simply kept as companion horses.


If you visit a horse farm, you will likely see mares and foals decorating pastures. One of those mares may just be watching over the future Kentucky Derby winner.

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