Natural service, commonly referred to as live cover, remains a prevalent breeding method within the equine industry, involving the direct physical mating of a stallion and a mare. This traditional approach offers a relatively cost-effective solution with fewer personnel demands compared to artificial insemination. Breeders can select between two primary natural service methods: pasture breeding and in-hand breeding, each with distinct benefits and drawbacks. While pasture breeding is often favored for its economic advantages and reduced handling requirements, in-hand breeding is typically reserved for high-value horses to minimize injury risks to both mare and stallion. However, successful in-hand breeding necessitates significant, specialized personnel training to ensure the safety of all involved. A critical consideration with natural service is the elevated risk of venereal disease transmission, underscoring the importance of rigorous testing protocols for horses participating in breeding programs. Identifying and managing common venereal diseases such as contagious equine metritis, equine viral arteritis, equine coital exanthema, and dourine is paramount for maintaining herd health.
Understanding Live Cover Breeding
Live cover breeding encompasses the natural mating process between a stallion and a mare, distinct from assisted reproductive techniques (ART) like artificial insemination. In artificial insemination, semen is collected from the stallion and then artificially introduced into the mare’s uterus. Natural service is widely adopted in the horse industry, with some breeds, such as Thoroughbreds, mandating foals be born from live cover to be eligible for registration. This method is often more economical and requires less veterinary intervention than artificial insemination programs. The two main approaches to natural service are pasture breeding and in-hand breeding.
Advantages and Disadvantages of Live Cover
Breeders must carefully weigh the pros and cons of natural service against more complex or costly alternatives like artificial insemination. The optimal choice depends on individual breeding objectives, the value of the horses, and specific breed registry requirements.
Advantages of Live Cover:
- Reduced mare management: Less intensive monitoring of mares’ estrus cycles is required.
- No need for stallion dummy training: Stallions do not need to be trained to mount a breeding dummy for semen collection.
- Registry compliance: Allows foals to be registered in organizations like The Jockey Club, which mandate live cover.
Disadvantages of Live Cover:
- Increased injury risk: Higher potential for injury to both the stallion and mare during mating.
- Venereal disease transmission: Sexual contact poses a significant risk for spreading diseases.
- Geographical limitations: Both the mare and stallion must be in the same location for breeding to occur.
Pasture Breeding
Pasture breeding typically involves housing a single stallion with a group of 15 to 20 mares. It is common practice to introduce the mares to the pasture one to two weeks before the stallion, allowing them to establish a social hierarchy. After the breeding period, some breeders opt for pregnancy checks, while others simply wait to observe which mares produce foals the following year.
Key advantages of pasture breeding over in-hand breeding include:
- Minimal horse handling: Significantly reduces the need for direct human interaction with the horses.
- Lower costs: Savings are realized from reduced handling and the absence of intensive estrus cycle monitoring.
However, pasture breeding also presents several disadvantages:
- Risk of injury: Unsupervised breeding increases the likelihood of injury to the stallion or mares.
- Delayed fertility identification: Fertility issues in either the stallion or mares may not be detected until after the breeding season concludes.
- Inaccurate conception dates: Determining an exact conception date for estimating the mare’s due date can be challenging.
Pen Breeding
Pen breeding is a variation of pasture breeding, conducted within a more confined space like a pen or corral. This method aims to provide a more controlled environment for natural mating while still allowing the horses to breed freely. In pen breeding, a single stallion is introduced to a mare in estrus within a secure, hazard-free pen.
Advantages of pen breeding include:
- Enhanced monitoring: Breeders can more easily observe the horses during mating.
- Intervention capability: The potential to intervene in cases of aggressive behavior.
- Time efficiency: The mare and stallion are only together during the mare’s estrus cycle.
- Controlled timeframe: Easier to ensure mating occurs within a specific period.
- Space conservation: Suitable for breeders with limited pasture space.
Disadvantages of pen breeding include:
- Limited movement: Less space for horses to evade aggression.
- Reduced efficiency: The stallion is focused on only one mare at a time.
- Constant supervision: Crucial for ensuring the safety of both horses.
- Aggression challenges: May not be suitable for particularly aggressive horses.
In-Hand Breeding
In-hand breeding, also known as controlled breeding, is particularly favored for high-value horses due to its ability to significantly reduce the risk of injury. This method, however, demands considerably more management and personnel involvement than pasture breeding. Under controlled conditions with handlers present, the safety of both the stallion and mare is prioritized during mating.
The primary advantage of in-hand breeding is the minimized risk of injury. Additional benefits include:
- Precise breeding dates: Accurate knowledge of breeding dates aids in estimating the mare’s due date.
- Semen evaluation: Post-breeding dismount samples can be collected for stallion semen evaluation.
- Hygiene: The mare’s perineum and the stallion’s penis can be thoroughly cleaned before breeding.
Disadvantages are mainly linked to the increased management and personnel requirements. In-hand breeding necessitates:
- Teaser stallion: A “teaser” stallion is maintained to identify receptive mares.
- Repeated teasing: Mares are repeatedly teased with the teaser stallion.
- Reproductive monitoring: Frequent rectal palpations or ultrasounds of the mare’s ovaries are needed to pinpoint the optimal breeding time.
- Trained personnel: At least three trained individuals must be involved in the breeding process.
Restraint and Protective Equipment
In-hand breeding mandates the use of appropriate restraint for both the mare and stallion to mitigate injury risks. Many breeding operations utilize a chain lead shank and/or a twitch for mare restraint. To prevent the mare from kicking the stallion, leg straps on one of her front limbs or breeding hobbles may be employed. Additional equipment can include kick boots to pad the mare’s hooves and leather neck aprons to protect her from the stallion’s actions. In some cases, sedation may be necessary for mares.
For stallions, handlers typically use a chain lead shank or a breeding bridle for control. Stallions receive training to ensure they lead, stop, and back up on command before breeding, reducing the risk of uncontrolled behavior that could endanger the mare and handlers. Stallions exhibiting rearing, striking, or biting behaviors require additional training or modification of the breeding shed setup. Adjusting the breeding shed configuration, such as positioning the mare within a stall so only her hindquarters are accessible, can sometimes help manage aggressive stallions. Stallions are generally easiest to handle immediately following breeding.
Handlers
The safety of handlers, especially those in direct contact with the stallion, is paramount. All individuals involved should wear protective gear, including a helmet, equestrian safety vest, and work boots. A minimum of three personnel are required: one to handle the stallion, one to handle the mare, and one to guide the stallion if necessary. Only qualified individuals should be present in the breeding area when horses are involved.
Breeding Location
The breeding area must be designed to ensure the safety of both the stallion and mare, minimizing injury potential. The floor should be non-slip and free of dust. Many facilities use synthetic or rubber flooring for adequate traction. The area should be kept as uncluttered as possible to prevent horses from becoming entangled.
Individual stallion preferences may influence footing choices, with some preferring to breed “uphill” rather than on a flat surface. Adjusting the relative height of the stallion and mare can also be managed by altering the breeding location. Mats can be placed behind a mare to provide easier access for a shorter stallion, or under her hind feet to elevate her for a taller stallion.
Breeding Procedure
The initial step in in-hand breeding involves introducing the mare to a teaser stallion to confirm she is in estrus and receptive. Mares are typically placed in a padded stock during teasing to protect them from injury if they kick or the teaser stallion strikes. If the mare is in heat, her perineum is thoroughly cleaned with soap to minimize bacterial contamination, and her tail is wrapped to prevent interference during intromission. It is crucial to rinse the mare thoroughly, as soaps and disinfectants can be spermicidal.
Any necessary restraints or protective equipment are applied, and lubricant is used on the perineum to facilitate breeding. The stallion’s penis is then thoroughly washed to reduce the risk of bacterial contamination of the mare’s reproductive tract, unless the stallion breeds regularly as this can disrupt the natural bacterial flora of the penis.
Once both horses are prepared, handlers lead the stallion to the mare’s flank, allowing interaction. As the stallion becomes erect, handlers permit him to mount. One handler pulls the mare’s tail aside to avoid obstruction during breeding. After mating, the stallion should be immediately removed from the breeding shed to prevent aggression. The handler then washes the stallion’s penis before he is returned to his stall or paddock.
Disease Prevention
The reproductive organs of both stallions and mares can harbor infectious agents that transmit through sexual contact. The risk of venereal infections is significantly higher in natural breeding compared to artificial insemination, where antibiotics in semen extenders can neutralize many bacterial pathogens. Breeding operations often implement disease testing protocols to mitigate the spread of venereal infections.
Bacterial Endometritis
Bacterial endometritis, an inflammation of the uterine lining, is a common condition following sexual contact in horses. It typically occurs when bacteria present on the mare’s perineum or the stallion’s penis enter the uterus during breeding. Endometritis can lead to infertility in mares, causing reproductive failures and economic losses. Common causative bacteria include Streptococcus, Klebsiella, Pseudomonas, and Escherichia coli. Thorough cleaning of the mare’s perineum and the stallion’s penis can reduce the risk of bacterial endometritis post-breeding.
Contagious Equine Metritis
Contagious equine metritis (CEM) is a bacterial infection caused by Taylorella equigenitalis. It typically results in vaginal infections and temporary infertility in mares, with stallions often showing minimal symptoms. Asymptomatic mares can serve as a source of infection for stallions. Pre-breeding testing for CEM is recommended for both stallions and mares. Veterinarians collect swabs from the clitoris and uterine lining in mares, or the penile shaft and prepuce in stallions, for laboratory culture or PCR analysis. Treatment involves antibiotics and thorough cleaning of external genitalia. Natural service can resume once a horse tests negative for the disease.
Equine Viral Arteritis
Equine viral arteritis (EVA) is a viral infection that damages blood vessels, leading to edema and swelling in the limbs and lower abdomen. EVA can cause abortion or pregnancy loss in up to 60% of pregnant mares. While primarily spread through respiratory secretions, EVA can also be transmitted venereally via semen. Diagnostic testing is advised for all stallions entering a breeding program, as many horses are asymptomatic carriers. Laboratory evaluation typically involves testing blood serum for antibodies against the virus. Stallions positive for EVA can still be bred, but only to mares previously affected by EVA or vaccinated against it. Vaccination against EVA is available for young stallions to prevent them from becoming asymptomatic carriers.
Equine Coital Exanthema
Equine coital exanthema is a viral infection caused by equine herpesvirus-3 (EHV-3). This highly contagious virus causes small erosions or ulcers on the vulva or penis that typically resolve within 2-3 weeks. EHV-3 remains latent in the horse’s reproductive tract and can reactivate, causing recurrent ulcerations. The primary impact on breeding operations is the loss of use of affected stallions, reducing their breeding capacity during the season. Affected mares may also miss breeding opportunities, potentially failing to become pregnant within the desired window. Prevention relies on thorough pre-breeding examinations to identify and isolate infected animals, thereby preventing virus transmission.
Dourine
Dourine is a lethal protozoal disease caused by Trypanosoma equiperdum, predominantly found in Africa, South and Central America, and the Middle East. While the exact transmission route is unknown, it is presumed to be venereal. Dourine causes fever, penile or vulvar discharge, and raised skin lesions, progressing to neurological disease and death. Approximately 50% of affected horses die within 6-8 weeks of symptom onset. Asymptomatic carriers exist, making pre-breeding testing essential for horses in dourine-prevalent areas. Some international regulations mandate the euthanasia of test-positive horses as part of eradication efforts.
Summary
Natural service in horses, encompassing pasture and in-hand breeding, presents a cost-effective breeding method with unique considerations. While it offers advantages in reduced management and veterinary involvement, it carries an increased risk of venereal disease transmission, necessitating rigorous testing protocols. In-hand breeding enhances safety by reducing injury risks but demands extensive personnel training and involvement. Key venereally transmitted diseases to be aware of include contagious equine metritis, equine viral arteritis, equine coital exanthema, and dourine, each requiring specific management and prevention strategies to ensure the health and reproductive success of equine populations.
