Admittedly, not all mare owners are breeders with expectations of making a profit. If they are claiming their horse operation as a business for tax purposes, they must at least show evidence of “intention to make a profit”. Regardless of the scenario, it would be safe to assume that all breeders would like to minimize their losses.

Economic analysis of broodmare management practices is relatively scarce in the scientific literature. Bosh and others (2009) examined the production records of 1176 Thoroughbred mares in central Kentucky (over 7244 mare years) to determine the effects of reproductive efficiency over time on mare financial returns. They determined that over a 7 year investment period, live foals must be produced in all but one year to yield a positive financial return, noting that mares are a long term investment due to the delay in return on investment. They found that 63% of mares did not produce a foal every year but brood mares produced for an average of 3.4 years before NOT producing a foal. Interestingly, a majority of the mares drifted in foaling date with  subsequent foaling seasons. The probability of producing a registered foal decreased with increasing mare age, foaling after April 1st and multiple matings per conception.

Logically, in order for a broodmare to provide annual income, she must produce a marketable foal each year she remains in the herd. Therefore, reproductive efficiency is paramount in maximizing financial return from broodmares. Among well-managed Thoroughbred mares only 82.7% (Morris and Allen 2002), 79.8% (Hemberg et al. 2004) and 78.3% (Bosh et al. 2009) produced a live foal.

Although feral horses reproduce with levels of efficiency that rival other domesticated species, managed horses have some unique reproductive challenges.
1. Genetic selection pressure is on performance traits rather than reproduction/fertility.
2. Breed registries’ Universal birth date January 1st, coupled with seasonality (average date of 1st ovulation April 1), and pressure to compete at young age create “imposed” breeding season of February 15 through June 15th in order to produce early foals.
3. Imposed season causes owners to attempt breeding mares during period of transition.
4. Average gestation length of 340 days leaves 25 day window to maintain 1 year foaling interval. Breeding on foal heat estrus is often associated with early embryonic loss.
5. Higher value mares or mares with foals that have sold/performed well are often allowed to remain in the breeding herd even after reproductive inefficiencies are evident.
6. Generation interval (time required to replace the mare) for horses is 4-6 years.

Brood Mare Selection/Evaluation
Pedigree, performance and progeny are the primary drivers in cost/value of brood mares and will consequently impact the value/profit of the foals they bear. However, a mare that scores high in the 3 P’s has little value as a broodmare if she cannot consistently produce foals. Though there is no guarantee of a foal each year, performing a breeding soundness exam can alert you to potential problems and allow you to assess your risk before making a large investment of time and money. The more extensive the evaluation, the more informed your decision making process.

An in-depth review of the mare’s medical, management and breeding history is the place to start. Age, vaccination history, feed, previous use, intended use, surgical history, disease problems, weight gain or loss, are some general considerations. Reproductively, consider breeding status (maiden, barren, open, pregnant), age of first breeding, breeding method, number of years bred, number of foals born, average date of first annual ovulation, ovulation interval, size of ovulatory follicles, teasing behavior, foaling dates, incidence of dystocia, foal heat ovulation and mothering ability.  If poor management is the cause of poor performance, that can be overcome.

A complete physical and reproductive exam will allow you to determine if problems are correctable.  The physical exam includes things that may contribute to breeding problems. Poor feet and leg structure or chronic lameness issues will make the mare unable to withstand the act of breeding. A mare in thin body condition will have delayed onset of the breeding season, require more cycles per conception and have a higher incidence of embryonic loss than mares in good flesh.  Mares with pelvic abnormalities may be at risk for foaling difficulty. Mares with overshot or undershot jaws and/or in need of dental care may have difficulty utilizing feed and forage efficiently and therefore may lose weight and condition.

Reproductive exams should be done during the breeding season for the most accurate estimate of breeding potential. External genitalia should be examined for conformation that might lead to pneumovagina (windsucking), urine pooling or fecal contamination. (A mare with poor vulva conformation should have a Caslick’s placed after breeding and confirmed ovulation.) Performing a rectal exam via palpation and/or ultrasound examination will allow determination of pregnancy status, cyclicity, follicle size, uterine tone and abnormalities. Vaginal and cervical exam using a speculum may reveal injuries that could influence the mare’s ability to maintain a pregnancy. Uterine culture and cytology assist in determining if a mare has a uterine infection. Negative cultures are required in many live cover scenarios. Endometrial biopsies result in a score that relates to the mare’s chance of carrying a foal to term.

Fooling Mother Nature
The mare is seasonally polyestrus with daylength serving as the environmental cue that synchronizes the breeding season with the time of year when survival of the foal and rebreeding is optimal. During short days, hormone levels are low and ovaries are small and inactive. As days lengthen following the winter solstice, mares will undergo a transition period during which they grow follicles and demonstrate erratic estrous behavior but do not ovulate. Around the first week of April, mares will grow an ovulatory follicle and will continue to have ovulatory cycles regularly through late summer/early fall unless they become pregnant.

With the universal birth date of January 1st and economic drivers for performance at a young age, breeders often push mares to foal in January. Considering that average gestation length in mares is 340 days, a mare must be bred in February to accomplish this. Mares placed under 2 hours of additional light at dusk beginning the last week in November and continuing through breeding will undergo transition earlier in the year and should begin ovulating in February (Sharp et al ). Use of extended daylength has also been shown to shorten gestation length and reduce the interval to rebreeding in pregnant mares (Hodge et al 1982).

Caveats: 1. Horses owners living in extreme northern climates should consider that shedding of the hair coat is also a response to increased daylength. 2. Horses need a period of short days in order to respond to the lights so beginning earlier or leaving horses under lights year round are counterproductive. 3. If you begin placing your mare under lights and then ship her to a breeder, it is imperative that the mare continue under lights until she is bred.

Breeding Post Foaling
Yearly foaling is important to maintain profitability. Average gestation length affords the brood mare manager a narrow 25 day rebreeding window to prevent the mare from drifting later in her foaling date each year. Mating on foal heat is a common practice to improve the chances of maintaining early foaling dates. The primary disadvantage is the increased occurence of pregnancy loss in mares conceiving on foal heat matings. The decision to breed on foal heat should be made on an individual basis considering conditions of her foaling and her progress post-foaling. Mares should be evaluated day 6-8 post foaling then every other day until ovulation. Any mare that has a complicated birth, delayed passage of the placenta, genital tract trauma, or delayed uterine repair should not be bred on foal heat (Blanchard & Macpherson, 2011).

Mares typically return to estrus 5-12 days post-foaling and ovulate day 10-20 (Loy, 1980). In a normal mare, uterine involution occurs by day 15 on average. Pregnancy maintenance is dependent on a healthy uterine environment. After breeding, the embryo remains in the oviduct until about day 6.5. If a mare ovulates day 10 or later post foaling, breeding on foal heat has a reasonable chance of being successful because the embryo will not arrive in the uterus until day 16 or later. Mares ovulating before day 10 should not be bred on foal heat. Rather, skipping foal heat and giving the mare a shot of prostaglandin day 5-6 post ovulation to “short cycle” her gives her a little more time for repair yet shortens the time to rebreeding compared to a spontaneous return to estrus.

Managing the Estrous Cycle
Though a stallion will mate a mare several times during a heat period in a pasture mating situation, there are cost savings as well as health advantages for mating mares only once per ovulation. Costs associated with the mating process might include hauling the mare to the stallion, booking fee, collection fee, shipping fee, and insemination fee. When a mare is bred multiple times per heat, the fees are multiplied. From a health standpoint, consider that when a mare is bred, there will be a uterine inflammatory response. Following insemination the sperm cells move quickly up the oviduct (~4 hours) and the seminal fluid remaining in the uterus must be cleared out. The routes of elimination are the lymphatic system and the cervix aided by uterine contractions. Older mares with stretched and sagging uterine horns as well as compromised lymphatics, often have uterine clearance issues. Uterine lavage along with oxytocin administration 6 hours post breeding have been shown to be effective in improving conception rates in mares with clearance issues(LeBlanc, 1994).

If your only breeding tool available were teasing scores and previous breeding records, you would likely cover your mare every other day, beginning on day 3 of heat, until she went out of heat. If you have access to palpation and ultrasound, you can do a fair job of predicting ovulation, allowing you to book a stallion only once or request a single shipment of semen. Through rectal exams every other day during heat you can tract follicle size, shape, and softness, estrous edema, uterine tone and cervical score.  A comparison of the cost of diagnostics versus multiple covers would help you decide the best approach. In addition, hCG or GnRH injection in a mare with a follicle greater than 35mm should result in ovulation 36 – 48 hours post injection. Again, there is a cost associated but that cost is recovered if you prevent the need to order a second shipment of semen.

Breeding Tools
There are a number of tools available to enhance reproductive efficiency. As you plan and prepare for your breeding season consider if you wish to us artificial lights to hasten the onset of the breeding season. Developing a teasing program and record keeping system is foundational to reproductive management. If using artificial insemination, determine the collection schedule and requirements or the stallion manager and establish good lines of communication.
If you are going to use hormones, determine which ones, how and when you will use them and work with your veterinarian to have them available (hCG, GnRH, oxytocin, Regumate). Determine what your standard procedure will be regarding rectal exams. For example: beginning day 3 of heat, check every other day through confirmation of ovulation, then day 14 post ovulation, day 30, day 45 and day 60 (gender determination)? If you have a double ovulation, you will need to check for twins and potentially crush one if they persist. Some people try to cut costs by using the veterinarian as little as possible. This often results in increased costs in the long run due to missed ovulations and pregnancy failure. Sometimes in addition to counting the cost for a procedure, you should consider the possible consequences of NOT doing the procedure. Ask if it is worth the gamble.

Stochastic Process
What is the likelihood of a mare producing a live foal every year?  According to Bosh (2009), this is a stochastic process. Stochastic is a statistical term meaning random, involving probability or guesswork. Is Bosh saying “Your guess is as good as mine”?  Economic consequences of management decisions affecting reproductive efficiency are routinely studied in food animal species but rarely in the horse industry. This is not surprising when you consider the fact that cows or sows no longer producing offspring are culled from the herd and moved into the food chain but brood mares are often kept around well beyond their productive years.

Cost calculation is a management tool that is often ignored. You may calculate cost per mare per year but cost per foal produced accounts for the mares that failed to produce a foal but were maintained in the herd. Variable/direct costs are those which directly impact production like feed, fuel, fertilizer, repairs, veterinary supplies and services, etc. Fixed costs/overhead are costs that occur regardless of level of production like equipment and facility depreciation, land taxes, family living expenses. Before a manager can reduce costs, they must know what their costs are and how they are allocated. When cost savings are identified, consideration must be given to the risks associated with reduced input. For instance, if changing to a less expensive, lower quality feed causes your mares to lose body condition and subsequently require more cycles per conception, the cost savings is no longer relevant.

There are no “one size fits all” recommendations for maximizing the financial return from broodmares. It is no surprise that in Bosh’s Thoroughbred study, the most valuable mares afforded the greatest profit. Similar to other investments, there are financial risks associated with raising, buying and/or breeding mares. One thing all mare owners should have in common is that the end goal is to produce a marketable foal. Many of the costs incurred in breeding horses will be the same whether you are breeding high end horses or pasture ornaments. To that end, it is wise to buy the very best that you can afford.

Bosh et al (2009) Equine Vet J 41, 883
Bosh et al (2009) Equine Vet J 41, 889-894
Henneke et al (1983) Equine vet J 15, 371
Hodge et al (1982) Am J Vet Res 43, 1752
Hemberg et al (2004) Reprod Dom Anim 39, 81
LeBlanc (1994) Eq Vet Edu 6, 39
Loy (1980) Vet Clin N Am: Lg Anim Pract 2, 345
Macpherson & Blanchard (2005) Eq Vet Educ 17, 44
Morris & Allen (2002) Equine vet J 34, 51-60