Home > Hoof Beats Magazine > Breeding Basics: Getting in Foal

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Breeding Standardbred racehorses is both an art and a science. For those who aren’t breeding at the commercial level, but would like to optimize the success of their breeding product either in the sales ring or on the racetrack, Hoof Beats presents part three of a seven-part series on breeding basics. This month’s topic, which is continued from the January issue of Hoof Beats, covers tips on increasing conception rates in broodmares.

USTA statistics reveal that each year, the U.S. Standardbred breeding industry shows an approximate 60-percent conception rate. What can we do to raise this figure? Larger breeding operations with veterinarians on staff boast conception rates of 80 percent and above, so gains must be made with smaller breeders.

We asked veterinary and breeding experts what they thought were the most important factors in ensuring the best possible outcome, specifically, what steps to take to ensure the mating will produce a healthy and marketable foal.

Offering a range of opinions including the importance of the breeder-veterinarian relationship, ensuring good mare health, cycling, uterine health, the timing of breeding and stallion fertility are veterinarian Etta Bradecamp, reproduction specialist at Rood & Riddle Equine Hospital in Lexington, Ky.; Richard Arnold, president of Willow Oak Ranch in Tennessee and Montana; and Jim Avritt Sr., an owner and breeder in Lebanon, Ky.

Get a Good Veterinarian

There are a number of essential components in any successful breeding program, but perhaps none more important than having a good relationship with a qualified veterinarian, especially around breeding time and in foaling season, Arnold said.

“When breeding mares, the ability to accurately read sonogram pictures of follicles and having a working knowledge of that mare’s ovulation history is important,” he said. “This can vastly increase the pregnancy percentages in your operation.

“All mares are not the same nor do their sonogram readings tell the same story. Only experience with individual mares permits predicting ovulation with confidence.”

Since almost all breeders are using shipped semen, Arnold said, the assistance of a knowledgeable vet can greatly increase your broodmare band’s pregnancy rate and reduce management time from repeatedly breeding the same cycling mares.

There are several things that a breeder can do prior to the breeding season to ensure that their chances for success are maximized, Bradecamp said. Most importantly, establish a relationship with a veterinarian experienced in equine reproduction, which is imperative for maximizing pregnancy rates.

“Working with a veterinarian that is familiar with each individual mare’s history allows for specific management strategies to be employed proactively instead of after several unsuccessful cycles of breeding have passed,” she said. “Every unsuccessful cycle is an economic loss for the breeder.”

Properly Prepare

Bradecamp said that there are several variables to consider to maximize conception:

-Ensure that mares are in good body condition and on a good plane of nutrition.
-Ensure that mares are cycling.
-Ensure good uterine health.
-Ensure good timing of breeding and good uterine health post-breeding.
-Ensure the stallion has good fertility.

According to Bradecamp, breeders should expect a 60-65 percent cycle conception rate with cooled shipped semen and an end-of-season pregnancy rate between 80-90 percent.

“However, these rates can vary greatly depending on the fertility of the stallion and mare,” she said. “Additionally, the effect of human factor in the management of the mare and stallion cannot be dismissed. Even with fertile mares and fertile stallions, poor management can result in reduced pregnancy rates.” 

Mare owners should also ensure that their mares are properly prepared for the breeding season. All mares--barren, maiden and foaling--should be in good body condition and on a good plane of nutrition as they enter the breeding season.

Barren mares, Bradecamp said, should have a complete breeding soundness exam prior to the breeding season to ensure that any potential problems that may affect fertility are identified, treated and resolved prior to the start of the breeding season.

“Those mares that presented problems during the prior season should be treated as `problem’ mares and a plan should be developed by the managing veterinarian to maximize that mare’s chance of becoming pregnant,” Bradecamp said.

To ensure that barren mares will be cycling at the start of the breeding season, she suggested they should be placed under lights at the beginning of December. Mares need to be under lights for approximately 60 days to initiate cyclicity; therefore, if they are placed under lights later, the effects will not be seen until two months after.

“Recently, lighted masks (Equilume) have become available that allow the mares to stay outside and be exposed to a small light installed within the eyecup of the mask,” said Bradecamp. “These masks are as effective as placing mares under lights in the traditional manner.”

Get Good Semen

At Willow Oak, as at most Standardbred operations, breeding is done through artificial insemination, usually with fresh shipped semen no more than 24 hours old.

“We always check the semen when it arrives after breeding to make sure it is good enough,” said Arnold. “The quality of shipped semen can be influenced by a number of factors, including the fertility of the stallion, the time of the breeding season it is collected and its shipping and handling.”

Arnold added that it is wise to never presume the quality until checked.

“The use of frozen semen requires special handling, usually under the supervision of a reproductive veterinarian,” he said.  

This is another place, Bradecamp noted, where the human factor can play a significant role in the success of a breeding program.

“If a stallion is overbooked and is being bred to more mares than he can achieve acceptable pregnancy rates in based on his sperm production, mares that may have become pregnant if bred with an adequate dose of semen will not become pregnant,” she said.  “Every breeding shed and stud farm should know at any given time what their stallions’ per-cycle conception rates are and what size book of mares each individual stallion can serve.”

Avritt considered one of the most important factors is to breed to a stallion that is fertile enough to allow the shipment of his semen by Fedex for “next day” insemination. 

“Otherwise,” he said, “if the semen has to be flown in for “same day” insemination the process becomes more expensive and more time-consuming.”

For example, if Avritt breeds to a stallion standing at Hanover Shoe Farms and has to have the semen flown in from their Pennsylvania operation to the airport in Lexington, Ky., it normally will not arrive until almost midnight. 

“Since the airport is approximately an hour away, this means that my mare will actually be bred between 1 a.m. and 2 a.m.,” he said. “Furthermore, it is fairly common for flights to be delayed, in which event I will not receive my semen until the next day and the purpose for having it flown in is therefore defeated.”

When choosing the stallion, the mare owner should research the stallion’s breeding history. It is important to know how many mares the stallion bred the previous season and what the stallion’s per cycle and end of season pregnancy rates were.

“While this information would not be available for a freshman stallion, a breeding soundness exam should be performed on all stallions prior to the season to ensure that there are no apparent problems present,” Bradecamp said. “It is imperative to remember that regardless of the results of a breeding soundness exam, the only true test of a stallion’s fertility is his ability to obtain pregnancies at an acceptable rate.”

Keep Checking

All mares, regardless of their status, should have a trans-rectal ultrasound exam and uterine culture and cytology (as determined by the veterinarian) prior to breeding,” said Bradecamp.

Endometritis, or infection within the uterus, results in decreased pregnancy rates.

“Early identification and treatment can aid in restoring a mare’s fertility,” said Bradecamp.

Mare management also plays an important role in ensuring that maximum pregnancy rates are achieved. Timing of breeding should be planned to ensure that ovulation occurs within 24 hours after breeding.

“This can be accomplished by administering an ovulating inducing agent such as deslorelin (Sucromate) or hCG 24 hours prior to insemination,” said Bradecamp. “Mares should be monitored for ovulation and fluid accumulation within the uterus the day after breeding and treated appropriately if needed.

“Pregnancy rates are decreased in mares that do not ovulate within 24-48 hours post-breeding and in mares that have greater than 2 cm of fluid within the uterine lumen 24 hours after breeding.”

Bradecamp said that mares that are identified as susceptible to retaining uterine fluid post-breeding should be treated with uterine lavage and ecbolics to aid in the clearance of fluid and inflammatory debris from the uterus.

“With good management, acceptable pregnancy rates can be achieved in these mares,” Bradecamp said. “Both poor timing of breeding and failure to identify problem mares result in significant decreases in pregnancy rates.”

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