SBS Frozen Semen

  • How many sperm do you put in a dose?

    A breeding dose prepared by an SBS Affiliated Laboratory includes a minimum of 800 million total sperm per dose AND exceeds the industry recommended minimum of 200 million progressively motile sperm per dose after thawing.

    See also:

    It Only Takes One...Right?

    Not All Frozen Semen is Created Equally

    Questions Every Mare Owner Should Ask Before Breeding With Frozen Semen

    What Exactly is a Dose of Frozen Semen

    What is Progressive Motility?

  • How many straws are required for one insemination dose?

    A breeding dose prepared by an SBS Affiliated Laboratory is standardized to comprise of eight 0.5mL straws. Semen is frozen at a concentration of 200-250 million/mL, resulting in a total of 800 million to 1 billion sperm in a final dose volume of 4mL. Given our minimum recommended post-thaw motility for commercial distribution of 30% progressive, each breeding dose therefore also exceeds the industry recommended minimum of 200 million progressively motile sperm per dose after thawing.

    See also:

    Not All Frozen Semen is Created Equally

    What Exactly is a Dose of Frozen Semen?

  • How do you test the quality of frozen semen?

    We perform a thorough post-thaw evaluation on 2 pooled straws from every ejaculate frozen. After thawing, the semen is cultured to confirm the absence of bacterial growth and sperm motility is evaluated both visually and using a Hamilton-Thorne CEROS model automated motility analyzer. We perform this motility evaluation after the thawed semen is diluted in extender and incubated at 37°C for 30 minutes. Computer assisted sperm analysis (CASA) allows objective evaluation of sperm motility and provides information on total and progressive motility as well as velocity parameters. However, one must remember that although motility is an indicator of relative cell health, fertilization is a complex process that requires numerous functional attributes of both sperm and egg. Therefore the true fertility of this or any frozen semen can only be determined by properly timed insemination of reproductively healthy mares.

    See also:

    Quality Control is at the Core of the SBS Difference

    Not All Frozen Semen is Created Equally

    What Exactly is a Dose of Frozen Semen?

    What is Progressive Motility?

    Test Breeding Mares as an Aid to Marketing Frozen Semen

  • What health testing do you perform on a stallion before freezing?

    For stallions collected in the European Union
    Semen must be collected and frozen at an approved stallion collection centre under specific quarantine and health regulations dictated by the EU member state.
    Health testing is required for:
    - Equine Infectious Anemia (EIA)
    - Equine Viral Arteritis (EVA)
    - Contagious Equine Metritis (CEM); two sets of 4 swabs (urethra, urethral fossa, prepuce and semen/pre-ejaculatory fluid) 7 days apart
    Some EU Affiliate locations also require testing for Glanders, Dourine and Equine Herpes Virus.

    Three different options are presented to EU member states for the production of frozen semen.
    1). Stallion must be resident for 30 days before the semen freezing session begins. In this case the stallion is subjected to health testing within 30 days of entering the collection center and not less than 14 days after he entered the collection center. For stallions continuously resident at the approved premises all of the above tests must be carried out at least once a year at the beginning of each breeding season.
    2). Resident stallions, (like situation #1) can be shuttled in and out from the collection center (up to a maximum of 14 days apart), but additional testing must be performed at fixed intervals during the semen freezing period (e.g. EIA every 90 days, EVA every 30 days and CEMs every 60 days).
    3). Non-resident stallions can be shuttled in and out of the collection center. Health testing must be performed before entry into the collection center and repeated 14-90 days after completion of the freezing session.
    The EU member country selects which rule they will follow. Italy and Germany follow rule number 1 and this is true for both domestic and export semen production. Sweden allows the clinician to select one of these options when freezing semen for export. When freezing semen for domestic use in Sweden, health testing for EVA and CEM must still be performed before the stallion enters the collection center and the collection center cannot freeze semen for export when a stallion being frozen for domestic use is on the premises. Ireland can choose from option 1 or 2.

    For stallions collected in North America
    Unlike in the EU, unless semen is being frozen for export, there are no mandatory health testing requirements for stallions that have been established by any government or veterinary regulatory body in the U.S. Likewise there is no requirement that semen be collected and processed in a facility that is inspected or approved by any government or veterinary regulatory body. In an effort to provide a high standard of quality produced and distributed from SBS Laboratories, we have established a health testing policy for all stallions entering SBS laboratories. There may be some variations in requirements by individual affiliate locations, however most all stallions are tested for:

    • equine infectious anemia (EIA) within 6-12 months of arrival
    • equine viral arteritis (EVA) within 30 days of arrival

    In addition many SBS laboratories also require that stallions be tested with negative results for vesicular stomatitis (VS) and contagious equine metritis (CEM).
    A testing schedule comparable to that described for the European Union is required when freezing semen for export, depending upon the requirements of the country of import.

    For stallions collected in Australia
    Similar to the US there is no mandatory health testing required for collection and freezing of semen for domestic use. Australia is recognized as being CEM free and has not had a reported case of EVA. Semen freezing for export must be collected and processed at an approved collection center and include the appropriate health testing dictated by the country of import.

    Please Note: The above health testing requirements are provided as general guidelines and may change from time to time in response to new government regulations, disease outbreaks and SBS policy changes. Always inquire with your affiliate laboratory to determine specific requirements.

    See also: 

    What Happens When Your Stallion Arrives at SBS?

    Should the US Adopt Stricter Controls on Cooled and Frozen Semen Production Facilities?

    Exporting Frozen Semen from the United States

    Stallion Owners in the Northern Hemisphere Should Explore the Breeding Industry Down Under

    Stallion Owners Should Explore Opportunities in Europe and the Middle East

  • How do I post my stallion to the Stallion Guide?

    The Stallion Guide is a FREE marketing tool we offer to our frozen semen clients.The new Stallion Guide offers the following advantages:

    • You can create detailed Stallion Profiles, including photos and videos
    • Interested mare owners will be able to message you through the website
    • You & your mare owners will be able to view and track frozen semen shipments online
    • You will gain exposure to a broad international audience

    Please see the following link for more information:

    How Do I Post my Stallion to the Stallion Guide

    If you experience any problems updating your stallion profiles, please feel free to contact SBS at (410) 885-3202, info@selectbreeders.com

    The Stallion Guide is a complimentary service for agent/owner’s of stallions with SBS frozen semen that is currently in storage with an SBS affiliate lab and meets our recommended minimum thresholds for commercial distribution.

Semen Collection For Freezing

  • How old does my stallion have to be for semen collection?

    We suggest a stallion be at least 3 years of age before starting semen collection. At this age most stallions have matured both mentally and physically and are able to handle the additional stress of becoming an active breeding stallion. Typically, by the age of three their testicles have matured and have begun producing sufficient semen which is suitable for cooling or freezing. It is possible to collect younger stallions and we have successfully collected and frozen semen from 2yr olds. However, we always caution stallion owners to be aware that at this age semen quality may not be acceptable for processing. Even if it is, total sperm production is often less than would be expected at maturity and therefore it may not be financially viable to proceed with a comprehensive semen freezing program at that time.

    See also:

    Collecting Semen from the Young Stallion

    Harvesting and Freezing of Equine Epididymal Sperm

    Why Freeze Stallion Semen?

  • How do you train a stallion to the breeding phantom?

    We take our time when training stallions to collect off of a breeding phantom because we want them to have an enjoyable experience in the breeding shed. A mare in heat is placed in the shed and the stallion is allowed to see her or touch her if necessary in order to obtain an erection. At this time we also teach the stallion to stand for washing of the penis. The mare is then placed alongside the phantom and the stallion positioned at the back, on the opposite side of the phantom, so he can reach over to sniff her. When the stallion rests his chest on the phantom while sniffing the mare, the typical response to arousal is to mount the phantom. Once he has mounted the phantom the mare is moved forward and the collector places the AV on the stallion’s penis. On average most stallions can be trained to collect off the phantom in one or two 30 minute sessions. It is important that training sessions are always positive and rewarding in order to instill a good attitude in the breeding shed for the future.

    See also: How to Train the Stallion on the Phantom

  • Do you collect stallions on the ground?

    Yes, we are able to train and collect some stallions on the ground. When possible, it is preferable for the stallion to mount a breeding phantom or tease mare, however, stallions with physical disabilities may not be able to accomplish this and ground collection is an alternative option. When a stallion is “ground collected” all four feet remain on the ground while the stallion is ejaculating. Success is in part dependent on the stallion’s demeanor, libido and physical disability.

  • Do you use chemical ejaculation?

    Yes, we may occasionally perform chemical ejaculation. The chemically induced ejaculate often does not contain the same proportions of sperm and fluid as a more physiologically obtained ejaculate, therefore, we use chemical ejaculation only when necessary.

    See also: Chemical Ejaculation of the Stallion

  • How long does it take to deplete stored sperm?

    Depletion of aged stored sperm, that do not withstand the rigors of freezing very well, typically requires at least three “clean out” collections and sometimes more depending upon the individual stallion and how frequently he has recently been bred. Some stallions have a tendency to accumulate sperm in the reproductive ducts and require many more clean outs to acquire good quality sperm.

    See also: 

    What Happens When Your Stallion Arrives at SBS?

    Sperm Accumulation in the Stallion

  • Why do you have to deplete stored sperm before semen freezing?

    Spermatogenesis is an ongoing process and sperm are produced and released from the seminiferous tubules at a constant rate. The stallion’s reproductive tract includes areas where these sperm are stored. Aged, stored sperm in the efferent ducts of the testes and epididymis have reduced longevity and a decreased ability to withstand the cellular stress of cooling or freezing and therefore post-thaw motility and fertility are usually compromised.

    See also:

    Sperm Accumulation in the Stallion

    Value of Collecting Semen on One Mount

  • Does my stallion have to stay at your facility during freezing?

    For U.S. Stallions
    Not necessarily. If a stallion is having semen frozen for domestic use, then he may be shuttled to the facility for collections and return to his resident farm. If a stallion is being frozen for export, then it depends on the requirements of the country the semen is being exported to. There is a provision in the EU regulations that allows for a non-resident stallion to shuttle in and out of the collection center as long as health testing is completed before entry to the collection center and within 14-90 days after the last collection. Exporting frozen semen to some other countries (Australia and New Zealand for example) may require that the stallion enter the collection center and remain there in quarantine during the entire freezing and testing period.

    For EU Stallions
    Three different options are presented to EU member states for the production of frozen semen.
    1). Stallion must be resident for 30 days before the semen freezing session begins. In this case the stallion is subjected to health testing before entering the collection center and not less than 14 days after he entered the collection center.
    2). Resident stallions, (like situation #1) can be shuttled in and out from the collection center (up to a maximum of 14 days away), but additional testing must be performed at fixed intervals during the semen freezing period.
    3). Non-resident stallions can be shuttled in and out of the collection center. Health testing must be performed before entry into the collection center and repeated 14-90 days after completion of the freezing session.
    The EU member country selects which rule they will follow. Italy and Germany follow rule number 1, therefore all stallions must be resident and trailering in and out is not an option. This is true for both domestic and export semen production. Sweden allows the clinician to select one of these options when freezing semen for export. When freezing semen for domestic use in Sweden, the stallion can shuttle in and out, but the collection center cannot freeze semen for export when a stallion being frozen for domestic use is on the premises. Ireland can choose from option 1 or 2.

    See also:

    Exporting Frozen Semen from the United States

    Stallion Owners in the Northern Hemisphere Should Explore the Breeding Industry Down Under

    Why Utilize a SBS Mobile Laboratory?

    Stallion Owners Should Explore Opportunities in Europe and the Middle East

  • How often to you collect semen for freezing and why?

    After the stallion has completed the depletion process, we will collect to freeze on an every other day collection schedule (3-4 freezes/week). We allow a day of sexual rest so that the stallion can recover and build up adequate sperm numbers to maintain the cost effectiveness of freezing while still not allowing so much rest that the quality of the ejaculates is compromised.

    See also: 

    What Happens When Your Stallion Arrives at SBS?

    The Economics of Cooled and Frozen Semen

  • How many doses of frozen semen do you get from each collection?

    This depends entirely on the sperm production of an individual stallion. The “average” stallion produces about 8 insemination doses per freeze when collected on an every other day schedule. The test freeze may be an exception. Since the ejaculate used for the test freeze is being frozen using multiple different protocols, it is not possible to predict how many of the protocols tested will result in marketable semen as some of the treatments may result in suboptimal post-thaw quality.

    See also:

    What Exactly is a Dose of Frozen Semen? 

    The Economics of Cooled and Frozen Semen

  • How long does it take to produce enough doses to breed 10 mares?

    The length of time it takes to produce enough doses to breed 10 mares really depends on the individual stallion’s sperm production, the number of cycles it will take to achieve pregnancy in individual mares and the number of doses used on each cycle.

    Sperm Production
    The “average” number of doses produced with each ejaculate frozen is 8, however this number varies dependent upon the individual stallion’s sperm production and may range from <3 to >20 doses/ejaculate frozen. Stallions are normally collected for freezing on a Mon-Wed-Fri schedule, therefore in one week an “average” number of 24 doses can be produced.

    Number of Cycles
    Not all mares will conceive on one cycle with natural cover or artificial insemination. Therefore if you want to be assured of maximizing pregnancies in this group of ten mares, one should conservatively plan on having enough semen for 2.5 breeding cycles per mare. A mare with good fertility and management should be able to conceive in 2 or less cycles.

    Number of Doses per Cycle
    Another consideration involves the timing of insemination with frozen semen and whether or not a mare will be inseminated once (either through a time-planned insemination or a single post-ovulation breeding) or twice (where the mare is inseminated pre- and post-ovulation). SBS recommends two doses of frozen semen are made available for each breeding cycle, so the mare owner can be managed using a convenient timed insemination protocol, see Management of Mares for Frozen Semen Insemination.

    Thus 2.5 cycles per mare, allowing two doses/cycle means that for 10 mares we need to freeze 50 doses of semen. Given that the average stallion can produce 8 doses per ejaculate frozen, it would take 6-7 freezes (2.5 weeks) to produce 50 doses of semen. This is a conservative estimate. Many stallion owners freezing semen for the first time usually allocate 3 weeks. The first week for clean out collections (Mon-Tue-Wed) and a test freeze (Fri) and two weeks of semen freezing on a M-W-F schedule, this usually results in 50-60 doses for the average stallion.

    See also:

    Reproductive Efficiency Reported by SBS Affiliate Labs

    The Hidden Value of Frozen Semen

    The Pros and Cons of Equine Frozen Semen

Freezing Semen

  • What is involved in freezing semen?

    To process semen for freezing, the raw semen is diluted with a standard skim-milk glucose based extender and centrifuged to concentrate the sperm cells and remove seminal plasma. Seminal plasma contains factors that can be both protective and harmful to sperm. Primarily it is advantageous to remove seminal plasma when freezing semen. In the past clinicians would remove all of the seminal plasma, however, current research suggests it is beneficial to retain some, because seminal plasma is known to moderate the inflammatory response of the uterus when presented with sperm cells. Following centrifugation the sperm are diluted into the freezing extender which has a complex formulation including sugars, salts, egg yolk, skim milk and a cryoprotectant, predominantly glycerol. The semen is loaded into straws and frozen in liquid nitrogen vapor. This can be accomplished by one of two methods; either by floating a rack of straws over liquid nitrogen in a Styrofoam box or by a specially designed programmable cell freezing machine. All SBS Affiliated Laboratories utilize programmable cell freezers. A programmable freezer offers the significant advantage of being able to reliably control the rate of cooling to an accuracy of 0.1 °C/min. This enables us to design defined and precise freezing protocols that are consistent and repeatable with every freeze. Freezing over vapor offers limited ability to adjust the rate of cooling and does not have the consistent repeatability. Once frozen the straws are transferred to storage in tanks of liquid nitrogen at -196°C.

    See also:

    Basic Principles and Techniques for Freezing Semen

    Harvesting and Freezing Equine Epididymal Sperm

    Quality Control is at the Core of the SBS Difference

    What is a Test Freeze?

  • What preparation is required prior to a test freeze?

    Aged, stored sperm in the efferent ducts of the testes and epididymis have reduced longevity and a decreased ability to withstand the cellular stress of cooling or freezing, and therefore post-thaw motility and fertility can be compromised. Thus, we usually perform a series of “clean-out” collections prior to the test freeze. Depletion of aged stored sperm typically requires at least three clean out collections and sometimes more depending upon the individual stallion and how frequently he has recently been bred. Some stallions have a tendency to accumulate sperm in the reproductive ducts and require many more clean outs to acquire good quality sperm. See our Blog article Sperm Accumulation in the Stallion.

  • Do all stallions have semen that can be frozen?

    Not all stallions can be successfully frozen. Our experience within the SBS Affiliate Network indicates that approximately 75% of all stallions with normal initial semen quality produce sperm that are able to withstand the stresses of freezing and thawing, based on the industry standard for commercial distribution of ≥30% post-thaw progressive motility.

    See also: 

    The Pros and Cons of Equine Frozen Semen

    Declining Fertility in Aged Stallions

    Can Genetics Turn the Art of Stallion Selection into a Science?

  • If my stallion cools well, does that mean he will also freeze well?

    Not necessarily. Most stallions that cool well can be expected to freeze acceptably but this is not always the case. Occasionally a very fertile stallion with good cooled semen pregnancy rates will not freeze well. The only way to determine how well a stallion will freeze is to run a test freeze in a series of protocols (different extenders and cooling rates) and perform post-thaw motility analyses to evaluate his freezing potential.

    See also: 

    The Economics of Cooled and Frozen Semen

    Can Genetics Turn the Art of Stallion Selection into a Science?

  • Is there just one procedure to freeze semen?

    There are perhaps as many methods to freeze semen as there are clinicians freezing semen and each clinician will often claim to have developed the best protocol. Unfortunately many of these methods have not been scientifically tested under controlled conditions and because of a lack of internal quality control the protocols are not consistent or repeatable. At SBS we have four different protocols that we evaluate in a test freeze. The difference between each protocol being in either the extender formulation or the rate of cooling; all other aspects of the freezing protocol are maintained the same. In addition, SBS employs a stringent quality control program throughout our affiliate network that is unique to the industry and sets us apart from our competitors.

    Some examples of where variation in freezing protocol may occur are as follows:
    - Straw Size
    Semen may be frozen in 5ml or 0.5ml straws; in addition some technicians may use cryovials or small packets. See below for an explanation on why we use 0.5ml straws.
    - Extender Formulation
    One of the greatest sources of variation is the extender formulation, despite the fact that all semen extenders contain the same basic key ingredients. Subtle differences exist in the chemical composition and cryoprotective agent used.
    - Sperm Concentration
    Semen can be frozen to varying success across a broad range of cell concentrations. The concentration the cells are frozen at will also impact the number of straws/dose and/or the total sperm/dose. At SBS each insemination dose of 8 straws contains 800 million to one billion total sperm.
    - Method of Freezing
    Semen can be frozen in a computerized cell freezer and different programs can be utilized that vary in the rate of cooling. Some technicians may freeze semen over liquid nitrogen in a polystyrene box. See below for an explanation on why we use a programmable cell freezer.

    See also: 

    Quality Control is at the Core of the SBS Difference

    The Test Freeze - The First Freeze Performed on a Stallion's Semen

  • Is there a difference in results for certain stallions with one procedure over another?

    Every stallion is an individual and they differ in response to the various freezing protocols. When we freeze a stallion for the first time we do a test freeze comparing four different protocols; the differences between each treatment being in either the extender formulation or the rate of cooling. We select for subsequent freezing the protocol which gives the best results as determined by post-thaw motility. Scientific research has not answered conclusively the question of why a stallion prefers one protocol over another; it is undoubtedly due to a combination of factors including the membrane composition of that stallion’s sperm, the components of his seminal plasma and his inherent ability to withstand semen freezing. However, our experience is that there are definite preferences between stallions as to which procedure will yield the highest post-thaw motility.

    See also:

    The Test Freeze - The First Freeze Performed on a Stallion's Semen

  • What happens if my stallion did not pass the test freeze?

    If your stallion does not produce commercial quality frozen semen (post-thaw progressive motility >30%) with one of the four basic protocols that we normally utilize for a test freeze, then we do have several other options to try. We have additional extenders available for both centrifugation and semen freezing that are particularly well suited to those stallions we consider to be marginal semen freezers. Also there are other semen processing techniques that we can try. So all is not lost if the first test freeze is unsuccessful as we have many other paths to follow.

    Occasionally, frozen semen may be produced that is below the minimum threshold of 30% progressive motility. If the progressive post-thaw motility is 25-30% we may be able to manage this semen to obtain pregnancies by adjusting the total number of sperm in the breeding dose. However, we always recommend confirming fertility by test breeding before considering commercial distribution. See our Blog article Test Breeding as an Aid to Marketing Frozen Semen. Frozen semen with a post thaw progressive motility of <20% we recommend reserving for use on your own mares. See our FAQ,  Can you get a mare in foal with semen less than 30% progressive?, under the section Frozen Semen Expectations

  • If my stallion did not pass the test freeze is it worth trying again?

    Absolutely! There may be many reasons for why the results of a test freeze were not ideal at that point in time. Perhaps the stallion came straight from the competition circuit and there are still some residual drugs or medications in his system, maybe he had an undetected fever or testicular trauma prior to semen collection that affected his semen quality, maybe he is still too young and semen quality will improve as he matures. Also, the quality of semen from some stallions, and therefore their freezability, may be dramatically affected by season. For example, if a test freeze was performed in late summer the semen quality may have been affected by heat stress. Thus, it may be advisable to wait 2 - 3 months to repeat the evaluation when the heat stress is removed. Furthermore new advances are occurring all the time in extender formulations and processing techniques that might make a difference the next time. For example, we had one stallion return to us every year for four years and finally on the 4th year we were able to produce commercial quality frozen semen. So it is always worth trying again at some point in the future.

  • My stallion has already been tested elsewhere; do you need to test him again?

    Any stallion presented for the first time to an SBS laboratory must undergo a “test freeze” procedure. This procedure is designed to determine not only if and how well your stallion’s semen will survive freezing and thawing but also which of the various freezing protocols will produce the best results. For an SBS test freeze procedure, the ejaculate is split into 4 fractions and frozen using 4 different protocols. They vary in the extenders used and the cooling curves employed. At SBS, we produce our own proprietary extenders for semen freezing at our central laboratories and distribute them out to each of the affiliate labs. The extenders are produced under strictly controlled conditions in large volume batches, tested extensively and adjusted to ensure that the proper osmolarity and pH are maintained. There are many different ways to freeze semen and other labs outside of the SBS affiliate network have their own methods that use different extenders and processing protocols. SBS is the only equine semen freezing company that has created a network of laboratories using standardized freezing protocols that are extensively quality controlled. Additionally, all SBS labs use the same methods for analysis and determination of post-thaw quality. Once a test freeze under SBS protocol is performed, those results will be available and utilized at all other SBS affiliate laboratories, which are extensively scattered throughout the United States, Europe, and Australia. This means that you can take your stallion to any one of our affiliate laboratories and expect the same semen freezing results as the original test freeze.

  • How many test freezes do you need to do to determine the best protocol for my stallion?

    Following proper depletion collections and evaluation, we generally perform one test freeze procedure, evaluate the results and determine if a second test is warranted. If the two “best” protocols yield similar results we may choose to split the next ejaculate into two fractions to see if there is a significant preference on a second comparison. Also, if the results of the first test indicate marginal or poor results and the owner is agreeable, we may experiment with alternative techniques to try and improve the results. Some low sperm producing stallions will not provide sufficient sperm in an ejaculate to allow the ejaculate to be split into 4 fractions and in these instances may require a second ejaculate to fully evaluate all 4 of our standard protocols.

  • Do you have to do a new test freeze each year?

    We normally do not repeat a test freeze from year to year unless we have a new extender or have changed the formulation since the stallion was last with us for freezing. Our experience is that the procedure preference does not change from year to year for a given stallion. Alternatively, if it has been several years since we last froze semen from the stallion or if he is not responding to freezing as well as on previous occasions we will repeat the test freeze in case his semen characteristics have changed.

  • Why do you use a programmed cell freezer instead of just freezing in vapor?

    A programmable freezer offers the significant advantage of being able to reliably control the rate of cooling to an accuracy of 0.1 °C/min. (active cooling). This enables us to design defined and precise freezing protocols that are consistent and repeatable with every freeze. In addition two or more different cooling rates can be incorporated into one freezing protocol. Freezing over vapor (passive cooling) offers limited ability to adjust the rate of cooling and does not have the same repeatability.

    See also: 

    Quality Control is at the Core of the SBS Difference

    What is a Test Freeze?

  • What size straws do you use and why?

    We use plastic (polyvinyl chloride) straws that hold 0.5 mL of volume in each straw. In the past, 4 ml or 5 ml macro-tubes have also been used to package stallion semen for freezing. In the last 10 years, SBS has opted to use 0.5 mL straws because a more consistent freezing rate within the straw can be achieved, as the straw diameter is considerably less than that of the macro straw. When the freezing rate of all of the sperm within the straw is consistent, then the overall quality of the semen is maximized once they are thawed and ready for insemination. Another benefit achieved from using 0.5 mL straws, is that they can be used with mechanical filling and sealing machines which ensure consistent filling of straws, a secure seal and a reduced processing time. Furthermore, 0.5 mL straws lend themselves to several different methods of convenient storage in either large or small goblets or on canes. Plus post-thaw evaluation of 1 or 2 (0.5mL) straws from each batch represents only 1/8 to 1/4 of a breeding dose.

    See also: 

    What Exactly is a Dose of  Frozen Semen?

    What is a Test Freeze?

  • How do you test the quality of frozen semen?

    We perform a thorough post-thaw evaluation on 2 pooled straws from every ejaculate frozen. After thawing, the semen is cultured to confirm the absence of bacterial growth and sperm motility is evaluated both visually and using a Hamilton-Thorne CEROS model automated motility analyzer. We also perform this motility evaluation after the thawed semen is diluted in extender and incubated at 37°C for 30 minutes. Computer assisted sperm analysis (CASA) allows objective evaluation of sperm motility and provides information on total and progressive motility as well as velocity parameters. However, one must remember that although motility is an indicator of relative cell health, fertilization is a complex process that requires numerous functional attributes of both sperm and egg. Therefore the true fertility of this or any frozen semen can only be determined by properly timed insemination of reproductively healthy mares.

    See also:

    Not All Frozen Semen is Created Equally

    What is Progressive Motility?

    Test Breeding Mares as an Aid to Marketing Frozen Semen

  • Why do you use two test straws and not just one?

    Two straws are combined to test for post-thaw quality to increase the probability that the results adequately represent the quality of all the straws in the ejaculate (as opposed to just a single straw).

    See also: Quality Control is at the Core of the SBS Difference

Frozen Semen Expectations

Breeding Mares With Frozen Semen

Health Testing and Disease Considerations

  • Does my stallion have to be tested against any disease before entering your facility?

    For stallions collected in the European Union
    Semen must be collected and frozen at an approved stallion collection centre under specific quarantine and health regulations dictated by the EU member state.
    Health testing is required for:
    - Equine Infectious Anemia (EIA)
    - Equine Viral Arteritis (EVA)
    - Contagious Equine Metritis (CEM); two sets of 4 swabs (urethra, urethral fossa, prepuce and semen/pre-ejaculatory fluid) 7 days apart
    Some EU Affiliate locations also require testing for Glanders, Dourine and Equine Herpes Virus.

    Three different options are presented to EU member states for the production of frozen semen.
    1). Stallion must be resident for 30 days before the semen freezing session begins. In this case the stallion is subjected to health testing within 30 days of entering the collection center and not less than 14 days after he entered the collection center. For stallions continuously resident at the approved premises all of the above tests must be carried out at least once a year at the beginning of each breeding season.
    2). Resident stallions, (like situation #1) can be shuttled in and out from the collection center (up to a maximum of 14 days apart), but additional testing must be performed at fixed intervals during the semen freezing period (e.g. EIA every 90 days, EVA every 30 days and CEMs every 60 days).
    3). Non-resident stallions can be shuttled in and out of the collection center. Health testing must be performed before entry into the collection center and repeated 14-90 days after completion of the freezing session.
    The EU member country selects which rule they will follow. Italy and Germany follow rule number 1 and this is true for both domestic and export semen production. Sweden allows the clinician to select one of these options when freezing semen for export. When freezing semen for domestic use in Sweden, health testing for EVA and CEM must still be performed before the stallion enters the collection center and the collection center cannot freeze semen for export when a stallion being frozen for domestic use is on the premises. Ireland can choose from option 1 or 2.

    For stallions collected in North America
    Unlike in the EU, unless semen is being frozen for export, there are no mandatory health testing requirements for stallions that have been established by any government or veterinary regulatory body in the U.S. Likewise there is no requirement that semen be collected and processed in a facility that is inspected or approved by any government or veterinary regulatory body. In an effort to provide a high standard of quality produced and distributed from SBS Laboratories, we have established a health testing policy for all stallions entering SBS laboratories. There may be some variations in requirements by individual affiliate locations, however most all stallions are tested for:

    • equine infectious anemia (EIA) within 6-12 months of arrival
    • equine viral arteritis (EVA) within 30 days of arrival

    In addition many SBS laboratories also require that stallions be tested with negative results for vesicular stomatitis (VS) and contagious equine metritis (CEM).
    A testing schedule comparable to that described for the European Union is required when freezing semen for export, depending upon the requirements of the country of import.

    For stallions collected in Australia
    Similar to the US there is no mandatory health testing required for collection and freezing of semen for domestic use. Australia is recognized as being CEM free and has not had a reported case of EVA. Semen freezing for export must be collected and processed at an approved collection center and include the appropriate health testing dictated by the country of import.

    Please Note: The above health testing requirements are provided as general guidelines and may change from time to time in response to new government regulations, disease outbreaks and SBS policy changes. Always inquire with your affiliate laboratory to determine specific requirements.

    See also:  Should the US Adopt Stricter Controls on Cooled and Frozen Semen Production Facilities

  • My stallion is EVA seropositive, can his semen be frozen?

    Yes, his semen can still be frozen. If your stallion is seropositive it means that he has circulating antibodies against the equine arteritis virus, either from previous natural exposure or from vaccination. A blood test cannot distinguish between antibodies that have developed against the actual virus or as a result of the vaccine. Even if your stallion is seropositive as a result of actual exposure to the virus, he may not have retained the virus in his reproductive tract (not all stallions do). The important step is to determine if the stallion is a carrier stallion and actually shedding virus in his semen. This can be determined by submitting semen samples to a recognized laboratory for attempted virus isolation in the semen from 2 separate ejaculates. If the semen is negative for the virus then the stallion is not a carrier and can breed mares without any restrictions or precautions. If he is a carrier and is actively shedding virus in the semen then it can still be frozen and used to breed mares but certain precautions must be taken (see the next question for further information).

    See also:  Should the US Adopt Stricter Controls on Cooled and Frozen Semen Production Facilities

  • My stallion is an EVA shedder, can his semen be frozen?

    United States
    Yes, his semen can still be frozen and in fact fertility does not appear to be affected but certain precautions need to be exercised. The arteritis virus will survive quite well in cryopreserved or cooled semen and must be stored in separate liquid nitrogen tanks. A declaration of the stallion’s EVA status must be made to mare owners so that they can take precautionary measures to protect their mares from contracting the virus. Only mares that have circulating antibodies against equine arteritis virus either from vaccination or previous exposure should be inseminated with semen containing the virus. Also, if you are shipping semen that contains arteritis virus into certain States within the U.S. (Utah, Montana and Washington) a special import permit must be obtained from the State Department of Agriculture. Please keep in mind that EVA positive frozen semen will not be able to be exported. Also, check with your local affiliate laboratory as many facilities will not allow carrier stallions that shed virus in their semen to be present on the property.

    European Union
    Stallions that shed equine arteritis virus in their semen are not permitted to enter an EU Approved Collection Center.

    It may be possible for an EVA positive stallion to be collected at a non-approved center depending upon the requirements of the country. For example, an EVA positive stallion can be collected at a non-approved collection facility in Sweden. His fresh and cooled semen can be used to breed mares providing the mare owner is aware of the EVA status and has taken precautions. However, even in Sweden semen from an EVA positive stallion cannot be frozen.

    See also:  Should the US Adopt Stricter Controls on Cooled and Frozen Semen Production Facilities

General Frozen Semen Questions

  • How long will frozen semen last?

    As long as the semen is not thawed, and is properly maintained in a liquid nitrogen storage tank, the working life is believed to be nearly unlimited. At SBS we have produced pregnancies with semen stored for more than 20 years. By utilizing the highest quality freezing extenders available, computer controlled rate cell freezers and maintaining rigidly controlled storage conditions, SBS maximizes the duration of sperm survival.

    See also:

    How Long Does Frozen Semen Last?

    The Hidden Value of Frozen Semen

    The Pros and Cons of Equine Frozen Semen

  • What is the recommended minimum post-thaw motility for frozen semen?

    SBS recommends that frozen semen used for commercial distribution contain > 200 million progressively motile sperm (PMS) after thawing with a minimum of 30% progressive motility. We measure post-thaw motility using an objective and accurate computer assisted semen analyzer (CASA) after the sample is thawed and incubated at 37°C for 30 minutes.

    See also:

    Quality Control is at the Core of the SBS Difference

    What is Progressive Motility?

  • Can't post-thaw motility vary with the laboratory performing the analysis?

    Yes, this is a valid concern. Post-thaw motility may vary depending upon:

    • The method of analysis
    • The time and temperature of incubation
    • The extender used for dilution

    Method of Analysis:
    At SBS we test post-thaw motility objectively by computer assisted sperm analysis (CASA). Clinicians without a CASA system determine motility visually by looking down the microscope and estimating the percent motility; this method is subject to observer bias and shows poor consistency of application and accuracy between technicians. However, there are still opportunities for the user to introduce bias into a CASA analysis; these include field selection and definition of the CASA settings. In our CASA system, a progressively motile sperm is defined as one that has an average path velocity (VAP) of > 50 microns/second AND is moving with a straightness value (STR) of > 75%. Since the thresholds for Progressive Motility can be set by the user it is important to understand that the clinician can increase the percentage of progressively motile sperm by lowering the thresholds for inclusion. It also means that two measures of motility by CASA cannot be definitively compared unless the machines operate with the same settings.

    Time and Temperature of Incubation:
    At SBS we test post-thaw motility after 30mins incubation at 37°C. This is to provide a stress test to the frozen semen that may reveal latent damage to the sperm caused by the freezing process that may not be evident immediately after thawing. Some clinicians may only look at sperm motility immediately after thawing. This value may be higher than a sample evaluated 30 minutes later and does not give any indication of the longevity of the semen. Temperature is equally important; sperm motility is best evaluated at 37°C, simulating the temperature within the mare’s reproductive tract. At SBS we pre-warm the tubes, extender and microscope slides used in the post-thaw analysis and evaluate the motility upon a heated microscope stage. Sperm analyzed at room temperature generally exhibit reduced velocity compared to a sample evaluated at 37°C.

    The Extender Used for Dilution:
    In order to perform an accurate CASA analysis the frozen semen must be diluted after thawing to an appropriate cell concentration. Since stallions are known to have extender preferences and sperm motility may vary between extenders, the extender selected for dilution of the thawed semen may influence the post-thaw motility. At SBS we dilute the frozen semen into the same extender that was used for centrifugation during the initial semen processing for freezing.

    See also:

    Not All Frozen Semen is Created Equally

    Quality Control is at the Core of the SBS Difference

    What is Progressive Motility?

  • What should I do with frozen semen that does not meet commercial quality standards?

    SBS does not recommend commercial distribution of semen with a post-thaw motility <30% progressive. One option is to destroy any doses which are below commercial quality. Alternatively some of our stallion owners reserve semen 20-30% progressive motility for use in breeding their own mares, adjusting the number of straws/dose to provide the recommending minimum of 200 progressively motile sperm/dose. There is no guarantee that by adjusting the number of sperm in the dose there will be comparable fertility to commercial quality semen as it depends whether the poor motility is due to compensable or non-compensable sperm defects.

    See also:

    It Only Takes One...Right?

    Not All Frozen Semen is Created Equally

    Test Breeding Mares as an Aid to Marketing Frozen Semen

  • I own some frozen semen of unknown quality, what can I do?

    You could submit 1-2 straws to SBS and we will perform a post-thaw analysis including sperm concentration, motility and a bacterial culture. This way you will know how many progressively motile sperm are in each straw and can adjust the number of straws per dose accordingly to ensure the best chance of conception. We particularly recommend this approach for any imported semen bought by the dose.

    See also:

    Not All Frozen Semen is Created Equally

    Quality Control is at the Core of the SBS Difference

    What is Progressive Motility?

    Test Breeding Mares as an Aid to Marketing Frozen Semen

  • What options do I have for buying frozen semen?

    There are three main questions mare owners should consider when purchasing frozen semen:

    • Domestic or international?
    • By the dose or by contract?
    • The service provider?

    In addition there are significant advantages you should consider for using SBS as your frozen semen provider.

    Domestic or International:
    One advantage of frozen semen is that the world is your market. Therefore your first choice is whether to purchase frozen semen domestically or internationally. Frozen semen can be available from stallions all over the world providing it is frozen with the appropriate health testing requirements for the country of import. There may be brokers in your country who have already imported international frozen semen so it is available domestically.

    In general, purchase & shipping of frozen semen domestically will be economically more viable than international shipment; however, this may not always be the case since it depends upon the value of the resulting foal. Furthermore, if you are looking to purchase more than just a couple of doses from an international stallion, it may be more economical to import directly from the owner, than to purchase the same semen from a domestic broker.

    With our International Affiliated Network of Laboratories, SBS is perfectly positioned to assist you with import of semen from another country. In our Stallion Guide, the stallion profile indicates whether a particular stallion has export qualified semen available and for what countries. We also have a list of Quarter Horse stallions that are already available in Europe and Australia here.

    By the Dose or by Contract:
    Traditionally frozen semen has been sold by the dose with no live foal guarantee. In our opinion, if you give a “live foal” or “return service” guarantee with cooled semen then you should also give the same guarantee with frozen semen. We feel that this is the fairest system for both the stallion owner and the mare owner. Selling semen by the dose encourages mare owners to try and minimize the number of doses used (purchased) so that a pregnancy is achieved at the lowest cost. This approach will result in much higher veterinary costs for management of the insemination of that mare and may also result in lower fertility in an attempt to conserve doses of semen. Therefore at SBS we recommend to our stallion owners that they sell frozen semen in a contract with a live foal guarantee, just like they would with cooled semen and we advocate our stallion owners provide at least two doses per cycle so the mares can be managed by a convenient and effective timed insemination protocol.

    See also: Contract Considerations for Exporting Semen

    Service Provider:
    An important consideration is that not all frozen semen is created equally. There are no enforced standards for frozen semen production in the US; which together with the potential variability in the post-thaw semen analysis means there is an inherent lack of quality control within the industry. Also because frozen semen is predominantly sold by the dose, brokers are under the financial pressure of getting as many breeding doses as possible from the available semen. Consequently they may cut the number of straws per dose potentially compromising the fertility of the semen. At SBS we are dedicated to improving the standards of quality control within the equine frozen semen industry and promoting the use of frozen semen through education and provision of a quality product.

    The distribution program should also be an important consideration when looking at frozen semen providers. There is nothing more frustrating than investing your money in frozen semen to discover that your provider has only 1 or 2 dry shippers and when you call for a shipment they are both checked out and it may be two weeks before they come back. At SBS we feel it is essential that the shipping process be as convenient, cost effective and as hassle free for the mare owner as possible.

    ADVANTAGES OF USING SBS AS A FROZEN SEMEN PROVIDER:

    • We have a pioneering quality control program throughout our Affiliate Laboratory Network
    • With our International Affiliated Network of Laboratories, SBS is perfectly positioned to assist you with import of semen from another country
    • We maintain a recommended minimum for commercial distribution of 30% progressive motility and 200 million progressively motile sperm/dose
    • We recommend to our stallion owners that they sell frozen semen in a breeding contract with a live foal guarantee and provide mare owners with a minimum of 2 doses/cycle.
    • We have an unparalleled distribution program for shipping of frozen semen that is designed for the convenience of the mare owner

    You can view some of the stallions available by SBS frozen semen on our Stallion Guide.

    See also:

    Importing Frozen Semen

    The Economics of Cooled and Frozen Semen

    Quality Control is at the Core of the SBS Difference 

  • What should I be aware of when purchasing semen from another country?

    • Is the semen qualified for export?
    • What is the semen quality?

    Is the Semen Qualified for Export?
    In order to qualify for export, semen must be frozen at an approved collection center and the stallion subjected to health testing requirements dictated by the country of import. The regulations and requirements for export/import of frozen semen vary depending upon the countries involved. To ship in semen from another country you must apply for an import permit from your ministry of agriculture.

    With our International Affiliated Network of Laboratories, SBS is perfectly positioned to assist you with import of semen from another country. In our Stallion Guide, the stallion profile indicates whether a particular stallion has export qualified semen available and for what countries. We also have a list of Quarter Horse stallions that are available in Europe and Australia here.

    What is the Semen Quality?
    It is important to get as much information about the frozen semen as possible - have pregnancies resulted from this frozen semen, what is the pregnancy rate per cycle or per season, what is the post-thaw motility and how is that motility evaluated? What is the concentration of sperm and how many straws constitute a dose? Each dose of semen should have at least 30% post-thaw progressive motility and contain a minimum of 200 million progressively motile sperm per dose. However, semen analysis can very between clinicians. If you have any concerns about the frozen semen we recommend that you have it analyzed by an independent lab, ideally before you invest in the purchase of a lot of semen and the associated importation costs. Our SBS affiliate locations in Europe, North America and Australia can assist you with semen import and analysis.

    See also:

    Importing Frozen Semen

    Questions Every Mare Owner Should Ask Before Breeding with Frozen Semen

    What Exactly is a Dose of Frozen Semen?

Storage and Distribution

  • How is frozen semen stored?

    For the maximum retention of fertility frozen semen must be stored properly. Specialized cryogenic containers (liquid nitrogen tanks) have been designed to maintain temperatures below -197°C (-320°F). After the freezing process, the straws of frozen semen are placed in plastic cups, known as goblets. Small goblets that hold 4-5 straws can be clipped into an aluminum cane and placed in a metal canister that has a designated compartment within the nitrogen tank. Alternatively, straws may be placed within larger goblets and stored in bulk within the canister. In order to maintain stability of the storage temperatures, the liquid nitrogen must be maintained above a certain level. We measure and record the liquid levels within each storage container on a weekly basis. At SBS large volumes of nitrogen are always available in pressurized nitrogen storage tanks (180 to 10,000 liters) to refill the semen storage containers as needed.

    See also:

    Proper Protocol for Receiving a Shipment of Equine Frozen Semen

    How Long Does Frozen Semen Last?

  • Can you store and distribute the frozen semen for me?

    Yes, SBS maintains the largest inventory of frozen equine semen in the world. All 25 of our Network Laboratories maintain secure cryogenic semen storage facilities. Our Texas and Maryland facilities store more than 30,000 doses each. SBS stores semen in special cryogenic vessels that utilize liquid nitrogen to maintain the frozen semen at temperatures of -197°C, which is critical for their long-term viability.

    Our distribution program has been designed to make shipping frozen semen cost effective and hassle free. Once a stallion owner sells a breeding, an authorization form is sent to the storage facility with the mare owner and veterinarians contact information as well as any specific instructions on the number of doses to be released, etc. Once that authorization is received, SBS takes care of the rest. A shipment request form is sent to the mare owner and/or veterinarian managing the mare. When the mare is coming into heat, the form is sent to the storage facility and the shipment is packaged and shipped out immediately by Priority Overnight along with illustrated instructions on the proper thawing, handling and insemination of the frozen semen.

    SBS labs maintain a large inventory of nitrogen vapor or “dry” shippers that are used to transport the semen and will maintain liquid nitrogen temperatures for up to 2-3 weeks. Semen can be shipped in advance of the date it is needed for insemination and transferred to the veterinarians storage container if available or the veterinarian can use the shipping container to maintain the semen during the mares cycle so that it is on hand and available when the mare needs to be inseminated.

    See also:

    How Long Does Frozen Semen Last?

    Proper Protocol for Receiving a Shipment of Equine Frozen Semen

    Understanding your Transaction Report

  • If I store semen at your facility, is it insured in case a tank goes bad?

    This will vary from one SBS Affiliate Lab to another, however many of the labs have liability insurance that will cover the cost of the semen up to the actual amount paid to have the semen frozen. If you would like to insure the frozen semen for a greater value, you will have to purchase additional insurance on your own. Please inquire with your SBS affiliate directly concerning their policies.

  • How do I order frozen semen from SBS?

    The specific ordering protocol may vary with each SBS Affiliated Laboratory; therefore we suggest you consult with the affiliate lab responsible for storing and shipping semen from the stallion you are interested in for specific details on their ordering protocol. However, we do share general principles. SBS is not a broker of frozen semen, inquiries regarding the purchase of a breeding to a particular stallion should be made to the stallion owner. Once the stallion owner has set up a service contract with a mare owner they will contact us to authorize release of frozen semen. We will not ship frozen semen to an individual unless we have authorization from the stallion owner on file. When the mare owner is ready for the frozen semen they call the SBS affiliate lab to request shipment. In most cases semen can be shipped the same day providing the request is made before 12pm. Frozen semen is shipped in “dry shippers” by Priority Overnight FedEx. Rental of the dry shippers varies between affiliate labs from 7-10 business days.

  • How do you ship frozen semen?

    Frozen semen is shipped in vapor shippers, so called dry shippers. The basic concept of these tanks is that they absorb liquid nitrogen into their walls. The tanks are filled with liquid nitrogen and thereby “charged” before use. Once fully charged the liquid is poured out of the container and the shipper can maintain temperature for 2-3 weeks. The tanks can be sent as non-hazardous material because there is no liquid nitrogen in the tank.

    See also:

    Proper Protocol for Receiving a Shipment of Equine Frozen Semen

    Understanding Your Transaction Report

  • Are the frozen semen shipments insured?

    We ship frozen semen by Federal Express Overnight (some labs can also ship same-day air on an airline). A value of $800.00 - $1,000.00 is placed on the shipment to cover the cost of replacing the container in case it is damaged or lost during transit.

    A higher value can be placed on the shipment to include the value of the semen. The difference in the fees charged by Federal Express (or the airline) for the higher value are to be paid by the consignee of the shipment. Federal Express will not cover the value of the shipment if it is delayed, damaged or destroyed due to an "act of nature." If the shipment is delayed or destroyed due to the negligence of Federal Express a claim can be filed to try and recover the funds for the product.

    We are not aware of an insurance company which has a program to insure frozen semen shipments. We have approached several companies in the past who were willing to write policies but there was little to no interest in the programs and they have been discontinued.

  • Is it possible to export semen to another country? What is involved?

    Yes, it is possible to ship equine frozen semen to another country.

    The first decision to be made is where you think there will be a market for frozen semen from your stallion. The countries which we export semen to the most are Australia, New Zealand, Mexico, Brazil, and members of the European Union.

    Most countries have written requirements for the import of frozen semen into their country but there are many which do not. We recommend the consignee in the foreign country obtain an import permit from their ministry of agriculture. The import permit will list the regulations and provide SBS with guidelines to be followed when housing, processing and/or testing the stallion. Although the semen we freeze will last indefinitely, the importing countries have the right to change their import regulations without prior notification.

    An import permit may detail:

    1.) The housing of the stallion - does he need to be resident at the collection facility or can he be trailered in/out?

    2.) The type and amount of testing which must be performed on the stallion and when.
    • Is it to be done before or after collection?
    • Is it to be done during a time frame in relation to the collection date or the arrival of the stallion at the collection facility?
    • Although the tests required can vary between countries the most common tests required are for CEM (Contagious Equine Metritis), EIA (Equine Infectious Anemia - Coggins), EVA (Equine Viral Arteritis), VS (Viral Arteritis). 

    3.) The period of time the semen must remain in storage at the collection center before it can be shipped

    4.) The type of collection materials must be used, what products can be used in the freeze extenders and what needs to be detailed on the health certificate.

    Prior to shipping semen internationally we require written authorization from the stallion owner to release the semen and information forms from the consignee.

    SBS takes care of:
    • correspondence with the consignee regarding the shipment details
    • preparing the health certificate and presenting it to the USDA for approval
    • sending the shipment to the destination country
    • verifying receipt of the container by the consignee
    • following up with the consignee to have the container returned to our facility

    We also have several affiliate labs in Europe and Australia. It is possible for us to include semen from your stallion in a bulk shipment to one of those facilities for storage and distribution. Our affiliate labs follow the same quality control standards and policies regarding the shipping of frozen semen.

    See also:

    Exporting Frozen Semen From the United States

    Quarter Horse Semen Available in EU and Australia

    Stallion Owners in the Northern Hemisphere Should Explore the Breeding Industry Down Under

    Stallion Owners Should Explore Opportunities in Europe and the Middle East

Using Frozen Semen

  • Should semen be diluted in extender after thawing and before AI?

    SBS does not recommend adding extender to semen after thawing and before AI.  See our article Should Frozen-Thawed Semen be Diluted Prior to Insemination?

  • Do I or my vet need special tanks to hold frozen semen?

    No. Select Breeders Service will ship enough frozen semen to manage the mare through one complete heat period. The shipping tanks are specially designed cryogenic vessels which maintain the frozen semen at -196°C for at least 10 days. This allows SBS to ship the semen to your vet well in advance of the anticipated insemination date avoiding the last minute rush to schedule semen shipments associated with cooled transported semen breeding. Also, if the mare fails to ovulate when predicted, no further shipments are required. There are sufficient doses of frozen semen in the tank to inseminate the mare again as needed. Of course, if you or your veterinarian own a liquid nitrogen storage tank, the semen could be transferred to this tank for storage.

    See also: Proper Protocol for Receiving a Shipment of Equine Frozen Semen

  • Is it difficult to thaw and inseminate with frozen semen?

    The actual process of thawing and inseminating frozen semen is quite simple. However one must follow specific thawing instructions precisely in order to obtain maximum post-thaw survival. This will require careful attention to detail and a temperature controlled water bath. The thawing protocol varies depending upon the size of the straw. Since the 1990s SBS has been freezing semen in 0.5mL straws, however older frozen semen may be packaged in 5mL straws. A detailed thawing protocol and printable instructions are available below:

    0.5mL straws

    5mL straws

    The equipment needed to thaw and use frozen semen is:

    • Accurate thermometer
    • Water bath
    • Hemostats or Tweezers
    • Timer or watch with second hand
    • Scissors
    • Sterile “red top” or centrifuge tube
    • All plastic syringe
    • Insemination pipette
    • Non spermicidal gel
    • Sterile insemination sleeve

    0.5mL Straws:
    Once the perineum of the mare has been aseptically cleaned, using a pre-cooled hemostat remove the straws from the nitrogen container and immediately place them into the 37°C water bath. Removing of straws from the tank should be done in 2-3 seconds at maximum. Once straws are plunged in the water leave them for at least 30 seconds to ensure proper thawing. The number of straws that comprise a single insemination dose may vary according to the freezing procedure employed. SBS standard protocol is to include 8 straws per insemination dose. Once all of the straws of the insemination dose have been thawed, remove them one by one and wipe the straws completely. Water would be spermicidal if comes in contact with the semen. Holding the straws vertically cut off the crimped or sealed end. Place the open end of the straws over a sterile, pre-warmed (37°C) container (i.e. red top blood tube, or centrifuge tube) and cut off the plug on the other end of the straws and allow the semen to empty into the sterile container. Tap the end of the straw to ensure that all of the semen is removed. Repeat this procedure for all of the thawed straws, combining their content into a single container. SBS does not recommend adding extender to the semen. Draw the thawed semen into a sterile pre-warmed insemination pipette using an all plastic syringe and inseminate the mare as you would with fresh or chilled semen. Use a 5 ml air dam behind the semen to ensure that all the semen is deposited in the mare’s uterus. It must to be kept in mind that all the equipment and material that comes in contact with the semen should be non toxic and not spermicidal.

    5mL Straws:
    Once the perineum of the mare has been aseptically cleaned, using a pre-cooled hemostat remove the straw from the nitrogen container and immediately place into the 50°C water bath.. Keep the straw in the water bath for exactly 45 seconds and then immediately remove the straw and place in a 37°C water bath or incubator. If the straw is left in the water bath for just a few seconds too long, this exposure to elevated temperature will irreversibly damage the sperm. Macrotubes are sealed with steel or glass balls and caution should be taken when thawing these tubes. If there is insufficient air space in the tubes or if the air bubble is not positioned in the middle of the tube, the straw may explode or the sealing ball may be expelled from the straw with tremendous force. You should always wear protective eyeglasses when thawing these straws. Once thawed; thoroughly dry the straws; water would be spermicidal if comes in contact with the semen. Shake the straw to position the air bubble at one end and cut off one sealing ball. Invert the straw so that the open end is positioned over a sterile, pre-warmed container (37°C) and cut off the other end to allow the semen to empty into the container. SBS does not recommend adding extender to the semen. Draw the thawed semen into a sterile pre-warmed insemination pipette using an all plastic syringe and inseminate the mare as you would with fresh or chilled semen. Use a 5 ml air dam behind the semen to ensure that all the semen is deposited in the mare’s uterus. It must to be kept in mind that all the equipment and material that comes in contact with the semen should be non toxic and not spermicidal.

  • What do I do with unused semen?

    The first thing to determine is who owns the frozen semen? If you purchased the frozen semen by the dose, you own the semen and any unused semen you could save for future use. SBS can store any remaining doses for you. If you received the frozen semen as part of a breeding contract then the stallion owner still owns the frozen semen. Check your breeding contract or call the stallion owner to discuss their policy for unused doses. Usually they will either request all unused semen be destroyed or returned.

    Please Note: The viability of frozen semen depends on proper handling and storage, maintaining straws at liquid nitrogen temperatures and minimizing any exposure to temperatures warmer than -100°C. Improper handling during transfer between transport containers and permanent storage, or failure to maintain proper liquid nitrogen levels in storage containers may damage semen. Once semen has left our SBS facility it is impossible for us to verify if the semen was damaged at the receiving location. It is SBS policy to only ship returned doses of semen back to that same mare owner or to the stallion/semen owner for their own use.

    See also:

    Contract Considerations for Stallion Owners

    Three Ways Stallion Owners Can Prevent Unapproved Use of Frozen Semen

Contract Considerations

  • How should I sell frozen semen?

    Frozen semen is typically sold one of two ways; either the semen is sold by the dose (typically without a guarantee) or it is sold as a breeding contract with similar provisions as a cooled semen contract. It is SBS’s position that frozen semen should be used as simply another means to fulfill the stallion owner’s obligation in a breeding contract between stallion and mare owners as opposed to being sold as a commodity on a per dose basis. We feel that this is the fairest system for both the stallion owner and the mare owner.

    See also:

    Frozen Semen Contract Guide and Templates

    Contract Considerations for Stallion Owners

    Test Breeding Mares as an Aid to Marketing Frozen Semen

    The Hidden Value of Frozen Semen

    Frozen Semen - Sell by the Dose or as a Breeding

    Contract Considerations for Exporting Equine Frozen Semen

  • Should I give a live foal guarantee?

    In our opinion, if you give a “live foal” or “return service” guarantee with cooled semen then you should also give the same guarantee with frozen semen. We suggest that breeding contracts for frozen semen are structured such that the costs associated with the production of the semen are separated from the value associated with the genetics. The mare owner pays a non-refundable fee that is set at a level that covers the production costs for the frozen semen required for the insemination through 2 heat cycles using a 2-dose timed insemination protocol. The balance of the fee is for the genetics of the stallion, which are only realized if a pregnancy is achieved and a foal produced. The contract can be written to provide for “up to N doses for the season” after which the mare owner has the option to purchase additional doses at a higher cost per dose if they want to continue trying to breed that mare. The balance of the fee or the “genetics fee” would only be paid if a pregnancy or live foal was produced.

    See also:

    Frozen Semen Contract Guide and Templates

    Contract Considerations for Stallion Owners

    Frozen Semen - Sell By The Dose or as a Breeding

    Contract Considerations for Exporting Equine Frozen Semen

  • How many doses should I ship per cycle?

    Most of our stallion owners provide 2 doses per cycle when shipping frozen semen. This allows for the practitioner to use a timed insemination protocol if appropriate. Some owners ship only one dose per cycle which then requires that the mare be managed very aggressively to ensure that insemination occurs within the period of 12 hours prior to or no more than 6 hours after ovulation. Either approach works well provided that the interval between insemination and ovulation is within the critical time period. There are a few important factors to consider when making this decision.

    • If too few doses are sent there is a possibility that insemination occurs too soon in relation to ovulation for a mare that holds on to a follicle longer than anticipated or doesn’t respond to an ovulatory agent. In this case a second shipment may be required to allow for proper timing of insemination. This is why SBS recommends that when only one dose of semen is available, mares are examined at 6 hour intervals around the time of anticipated ovulation and a single insemination is made within 6 hours post-ovulation.

    • If multiple doses are shipped per cycle, there is a possibility that the mare becomes pregnant with one dose and then there are doses remaining (presumably in storage at the vet clinic) that must be accounted for. If semen is sold by contract as opposed to “by the dose” be sure to specify in your contract who owns those doses and what is to be done with any unused doses of semen.

    Some owners have expressed concerns that if semen is sold by breeding contract that unused doses of frozen semen remaining after the original mare becomes pregnant may be sold to a 3rd party or used to inseminate another mare without payment of any additional stud fees. This is not a concern in breeds where a breeding certificate is required for foal registration and registration is important. We recommend that stallion owners specify the policy concerning unused frozen semen in the breeding contract and require that the inseminating veterinarian sign an insemination certificate that specifies the mare inseminated and dates that the inseminations occurred and that any unused doses where returned or destroyed as per the contract.

    See also:

    Frozen Semen Contract Guide and Templates

    Contract Considerations for Stallion Owners

    Effect of Number and Timing of Equine Frozen Semen Inseminations on Fertility

    Frozen Semen - Sell by the Dose or as a Breeding

    Three Ways Stallion Owners Can Prevent Unapproved Use of Frozen Semen

    The Pros and Cons of 1 or 2 Dose Insemination Protocols

    Contract Considerations for Exporting Equine Frozen Semen

  • How should I structure my breeding contract?

    At SBS we suggest that breeding contracts for frozen semen are structured so the costs associated with the production of the frozen semen are separated from the value associated with the genetics. The mare owner pays a non-refundable “booking fee” that is set at a level to cover the production costs for the frozen semen for that mare. The remaining balance, or stud fee, is for the genetics of the stallion, which are only realized if a pregnancy is achieved and a foal produced. The contract can be written to provide for “up to N doses for the season” after which the mare owner has the option to purchase additional doses at a higher cost per dose if they want to continue trying to breed that mare or you may wish to offer them the opportunity to return the following season, in which case they would repeat the booking fee. The cost of the frozen semen shipment is then paid by the mare owner and in most cases this is cheaper for them than covering the cost of collection, processing and shipping of a cooled semen shipment.

    To calculate your production costs of the frozen semen for each mare you divide the total cost of freezing the semen by the number of doses frozen - this gives you your cost per dose. Based on the number of doses you decide to allocate to each mare per season, you can then calculate your cost per mare.

    See also:

    Frozen Semen - Sell By the Dose or as a Breeding?

    Three Ways Stallion Owners Can Prevent Unapproved Use of Frozen Semen

    Contract Considerations for Export Semen

    Frozen Semen Contract Guide and Templates

    Contract Considerations for Stallion Owners

    Contract Considerations for Exporting Equine Frozen Semen

  • Why does SBS recommend selling frozen semen as part of a contract rather than by the dose?

    1). Unlike bovine frozen semen which is sold by the dose as a commodity, the frozen semen from young stallions is not thoroughly fertility tested before being sold on the market. A dairy farmer who purchases a dose of frozen semen from a Holstein bull from a reputable AI or genetics company can be very confident of the fertility potential of that dose of semen when handled properly and inseminated into a fertile cow. The reason for this is that dairy sires have been selectively bred for milk production AND fertility, more specifically fertility in an AI program with frozen semen. The range in fertility per cycle for commercial AI bulls is very small and only a few percentage points separate high fertility bulls from average and low fertility bulls. Furthermore, bulls with low fertility with frozen semen are not commercially viable and are culled from commercial production so their frozen semen never reaches the market. Fertility testing of a young dairy sire’s frozen semen involves the insemination of thousands of cows to provide the estimate of fertility for that bull and the basis for which the decision is made to keep him or cull him from commercial production. Contrast this to the situation with horses. Even if one had the required number of mares available, stallions do not produce the number of AI doses per ejaculate required to practically or cost effectively fertility test their frozen semen. Stallions are not selected based on fertility, let alone how well their semen freezes. The best a mare owner can hope for is that the semen has been frozen by a reputable laboratory with proven protocols and that the frozen semen has undergone a thorough post-thaw evaluation and that any semen put on the commercial market meets strict quality standards based on available critical laboratory assays. It is our position that the risk associated with breeding horses (by any means) should be shared by the stallion and mare owners.

    2). Selling semen by the dose encourages mare owners to try and minimize the number of doses used (purchased) so that a pregnancy is achieved at the lowest cost. This approach will result in much higher veterinary costs for management of the insemination of that mare and may also result in lower fertility in an attempt to conserve doses of semen.

    3). Frozen semen sold by the dose is often sold without any restrictions on the number of breeding certificates issued and may encourage a mare owner to split multiple straw doses for insemination of more than a single mare. This could lead to lower overall fertility from many stallions and contractual problems between mare and stallion owners.

    See also:

    Frozen Semen Contract Guide and Templates

    Contract Considerations for Stallion Owners

    Frozen Semen - Sell By the Dose or as a Breeding?

    Not All Frozen Semen is Created Equally

    Contract Considerations for Exporting Equine Frozen Semen

  • Why do many stallions owners sell semen by the dose?

    Stallion owners who sell semen by the dose cite the following reasons:

    1). They have no control over how the semen is handled and utilized therefore they do not want to be responsible if a mare owner and their vet do not manage the mare carefully and waste semen. They feel this is especially true if the semen is sent to a broker in another country and then sold to a mare owner.

    2). They get paid up front and do not have to worry that mishandling or poor management will result in bad fertility.

    3). They typically charge a fee per dose that is equal to one third to half the cost of a guaranteed breeding contract and this is typically well in excess of the cost of the production of that frozen semen.

    The advantage here is completely with the stallion owner, the mare owner takes on all the risk at considerable expense.

    See also:

    Frozen Semen Contract Guide and Templates

    Contract Considerations for Stallion Owners

    Frozen Semen - Sell By the Dose or as a Breeding?

    Not All Frozen Semen is Created Equally

    Three Ways Stallion Owners Can Prevent Unapproved Use of Frozen Semen

    Contract Considerations for Exporting Equine Frozen Semen