Horse Semen for sale - Brownmill Stallions

 Stallion Sperm Collection Process

Semen collection for the purpose of reproductive evaluation or for use in artificial insemination is widely practiced in modern horse breeding. Although semen collection can be performed on jump mares, the standard accepted method is to train the stallion to mount a phantom, or dummy. Stallions can be readily trained to serve the artificial vagina. Stallions trained to perform in these conditions do not necessarily lose their ability to breed naturally. Semen collection using a phantom, however, is characterized by a complete absence of auditory, olfactory, and vaginal contact and contraction stimuli. It is well established that these stimuli reinforce erection and ejaculation in the stallion.⁴⁰ Some studies have reported that more mounts are necessary per ejaculation for semen collection than in natural cover.³⁹ In a recent study comparing behavior during natural cover and semen collection on a phantom in 42 stallions, however, no statistically significant difference was found in erection latency (62 ± 22 seconds for natural service versus 100 ± 13 seconds for phantom collection) and ejaculation latency (84 ± 18 seconds versus 86 ± 28 seconds, respectively).³⁷ These findings suggest that appropriate training and adjustment of artificial vagina conditions (temperature, pressure, and position) are important and should be adjusted for each stallion to allow a repeatable technique for adequate semen collection.^41,42

In my experience, training of a novice stallion to semen collection using an artificial vagina and an estrous mare is successful in more than 90% of instances after one or two attempts. Training for semen collection on a phantom may take a little longer. Steps for training stallions for semen collection on dummies have been thoroughly described. The key points in this technique are to use an estrous mare for stimulation of the stallion and to allow a few mounts on the mare, alongside the phantom, before attempting in a later session to divert the stallion’s mounting efforts to the phantom.⁴³ Presence of an estrous mare is not necessary after initial training.³⁷ Semen collection on a phantom or on the ground (i.e., standing collection) does not affect natural cover, and vice versa.

                   The Artificial Vagina

Semen collection using an AV is the most widely used method of semen collection from stallions. Many models of equine AVs are available. These are fitted with a water jacket that allows for the passive control of the internal temperature of the liner, usually 44° to 48°C. In most cases, the internal diameter of the AV can be modified by the addition of water or air to the water jacket. A lubricant is manually added to the innermost liner of the AV to alter the degree of friction during breeding. Lubricants containing bacteriostatic or spermicidal compounds should not be used to lubricate the AV because these compounds are detrimental to sperm motility.⁶ Petroleum jelly (Vaseline) or methylcellulose (H-R Lubricating Jelly, Carter Products, Division of Carter-Wallace, Inc, New York, NY) can be safely used. A recent clinical trial compared the effect of four different “non-spermicidal” lubricants on the longevity of sperm motility.⁷ Three of the four lubricants tested were detrimental to sperm motility. The lubricant Pre-Seed (Ing-fertility, Valleyford, WA) did not suppress motility compared with controls. Possible reasons for the detrimental effect of lubricants include hyperosmolarity and unphysiologic pH. Careful selection of lubricant as well as the amount used are important factors in the semen collection process. Most commercially available AVs can be modified to allow the incorporation of a filter into the semen collection system, if desired, so that dirt, debris, and gel can be removed from the semen sample. Otherwise, the entire ejaculate can be filtered after collection, or the gel can be aspirated from the sample using a syringe. Sperm losses during the collection process have been determined with one model of AV.^8,9 Most of the sperm lost during collection is accounted for in the filter and in the gel fraction of semen. Between 25% and 30% of sperm in an ejaculate can be lost in the gel and filter. Polyester filters tend to absorb seminal fluid and therefore reduce sperm recovered in the gel-free ejaculate. Nylon filters do not absorb fluid but allow considerable trapping of sperm in the gel fraction.¹⁰

Ideally, the AV is constructed to maintain the desired AV temperature for a significant period, to allow the direct ejaculation into the semen receptacle, and to allow for ease of handling and manipulation by the operator. If the AV is large and heavy, the operator may have difficulty positioning the AV for tall stallions, for stallions not trained to the AV, or when the mount mare moves during collection. It is best if the AV can be held in one hand, at the appropriate position, while the other hand is used to deflect the base of the penis to the side of the phantom or mount mare. This is particularly helpful in stallions that thrust with significant force. Deflecting or stabilizing the base of the penis is stimulatory to most stallions and may help prevent preputial hematomas during the collection process.

Semen collection failures are frequently associated with inappropriate AV positioning for the particular stallion, an AV that has dropped in temperature below a “critical” point for the stallion, the phantom mount set too low, and the use of excess pressure in the AV. The AV should be held parallel to the ventral abdomen of the stallion and in direct alignment with the base of the stallion’s penis. In this manner, ventral or lateral bending of the penile shaft is avoided.

In certain circumstances, it may seem necessary to elevate the internal temperature of the AV to 50°C for stallions with difficulty ejaculating into the AV. However, an effort should be made to have the horse ejaculate directly into the semen receptacle or coned portion of the AV liner to avoid heat shock to the sperm. Sperm cells exposed to excess heat from the AV liner exhibit a circling-type motility, have reduced sperm longevity in raw and extended semen, and may be rendered infertile. Exposure of semen to elevated temperatures for as little as 10–20 seconds is sufficient to cause heat shock damage.

Successful cryopreservation of semen (frozen semen) was first performed in the early 20th century with bull semen and is extensively used in the cattle industry today. The first pregnancy resulting from frozen stallion semen occurred in 1957 in the US when spermatozoa were taken from a stallion’s epididymis, frozen, thawed and inseminated into a mare. Interest and necessity have rapidly grown to transform equine semen cryopreservation throughout the world into a successful industry.

Equine semen is far less tolerant of the freezing and thawing process than bull semen. Furthermore, not all stallion semen freezes alike. No single technique or magic formula exists to freeze all equine semen. Semen from some stallions fairs better than others with certain freezing media. Some stallion’s semen does not freeze well and may require extensive testing and laboratory procedures in attempting to preserve the spermatozoa. Furthermore, at different times of the year and even at different collections, tolerance of the freezing and thawing process may show some variation in an individual stallion.