Pharmacological aids are used to induce ex-copula ejaculation or to reduce the ejaculatory threshold in stallions with ejaculatory dysfunction. Specific ejaculatory disorders that can be treated with pharmacological aids include anejaculation, mounting and thrusting deficits in stallions with musculoskeletal or neurologic disorders, and psychogenic dysfunction.
Semen can also be collected on the ground, either by manual manipulation of the penis or with an artificial vagina. Ground collection is used in stallions with neurologic signs that are unstable to mount a mare.
Semen can be shipped to the mare’s farm cooled at 4°C for use within 24 to 48 h of collection. Semen is collected at the VHC. A complete semen evaluation is performed be veterinarians in all ejaculates, that includes evaluation of sperm motility, morphology and total numbers. The appropriate volume of semen is diluted in semen extender so that each insemination dose contains at least 1 billion progressively motile sperm. Semen is then packaged in a disposable shipping box or an equitainer. Both devices passively cool the semen at the appropriate rate during transportation. Semen is shipped overnight via commercial courrier. The VHC also offers counter-to-counter shipping service via commercial airline for same day delivery of semen, if needed.
Semen collection, evaluation and freezing is performed at the VHC. The first time a stallion is scheduled for semen freezing, a test freeze is performed. Semen is frozen using two different semen extenders and freezing techniques to determine the optimal protocol for each stallion. Once the optimal protocol is identified, subsequent ejaculates are frozen using that procedure. We thaw one straw from each batch to evaluate post-thaw viability. Stallions can be housed at the VHC until the number of insemination doses requested by the owner is obtained, or the procedure can be performed on an out-patient basis. One day of sexual rest is allowed between collections to maximize the number of spermatozoa obtained per collection. While semen freezing is offered year-round, ejaculates collected during the winter yield the lowest number of spermatozoa and straws. Unless requested otherwise, frozen semen is stored at Kansas Artificial Breeding Service Unit (KABSU).
A reproductive or breeding soundness exam (BSE) is an assessment of the stallion´s ability to impregnate a group of mares. It evaluates factors that influence his ability to establish pregnancy, such as quality and quantity of spermatozoa, libido and mating ability, physical defects or lesions of the genital tract, venereal infectious diseases and heritable defects. A BSE allows owners and veterinarians to identify subfertile stallions, determine the cause of infertility, make recommendations for the breeding management of the stallion, determine the number of mares the stallion can breed that breeding season and eliminate stallions with heritable defects. BSEs are preformed routinely at the beginning of each breeding season, any time subfertility is suspected, or as part of a pre-purchase exam.
A stallion BSE includes: a) a physical exam that assesses the presence of conformational abnormalities, lameness, back pain, neurologic signs and heritable diseases, b) a genital exam that includes visual, manual and ultrasonographic evaluation of penis, prepuce, scrotum, testicles, epididymides, ampullae, prostate, vesicular glands and bulbourethral glands, c) testicular measurements and estimation of daily sperm output, d) bacterial culture of semen, penis, urethra and prepuce, e) two complete semen evaluations performed one hour apart, that include assessment of semen volume and physical characteristics, sperm concentration, total numbers, motility and morphology. In addition, a semen shipment test can be performed. Semen is extended in various semen extenders that contain different formulations and antibiotics, and cooled to 4°C in a semen container. The test evaluates sperm’s ability to tolerate cooling and identifies the semen extender that best preserves that stallion’s sperm viability during cooling.
Spermatozoa are produced within the testicles. After a period of maturation, spermatozoa are stored in the tail of the epididymes until ejaculation. Spermatozoa within the tail of the epididymis have already acquired fertilization ability. In the event of death of a stallion, the epididymes can be removed and the spermatozoa stored in the tail can be retrieved. These spermatozoa can be frozen and used for artificial insemination of mares with acceptable conception rates.