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

Posted by Paul Loomis on Tue, May 22, 2012 @ 04:02 PM

In the United States there are very few regulations concerning the collection, processing, distribution and insemination of stallion semen. Any owner who can manage to extract semen from his or her stallion can without any prior training, experience, certification or license, sell semen from that stallion without restriction of any kind. There are only a few individual states that require certain testing for diseases potentially transmitted in semen but in most cases there is no requirement for such screening within the breeding population in the U.S. The USDA has regulations concerning the importation of semen and breeding animals into the U.S. from other countries but there is no USDA oversight to regulate the horse breeding industry within the borders of the country. This is also true in many other countries as well.

In the European Union there are strict regulations for any semen collection or AI center that is processing and shipping cooled or frozen semen among member countries of the EU. Those same requirements must be met by semen collection centers in the U.S. and other countries that wish to collect process and ship semen into the EU. The USDA in this country performs the biannual site inspections to verify that the collection center meets the requirements established by the EU for approval. Those requirements include strict standards aimed at minimizing the risk of spreading disease in the horse breeding population and include among other things:

  • health testing for a variety of diseases for all donor stallions
  • facility supervision by an accredited veterinary professional
  • specific requirements for the separation of donor animals from the general horse population
  • separate facilities for semen collection, semen processing and semen storage
  • use of new, disposable or disinfected equipment for semen handling
  • facility construction that permits thorough disinfection

There are not however any regulations concerning standards for semen quality. In other words, no regulations exist concerning the number of sperm in a dose of semen or the quality of those sperm (motility, morphology, etc).

Before transported semen, mares went to breeding farms with experienced stud farm management and vet care. If a stud farm had bad management then they sent mares home open and possibly infected and eventually went out of business. Similar market forces exist with transported cooled and frozen semen but it is much more difficult for a mare owner to sort out the problems since now you have multiple parties involved. There is the stallion management responsible for health care and disease testing, the laboratory responsible for collection, evaluation and processing for cooled or frozen semen, possibly a broker or storage facility responsible for proper storage and handling of for frozen semen and finally the veterinarian or technician managing the mare and performing the inseminations. Mismanagement of any of these areas due to inexperience or carelessness can result in poor sample quality, open mares or disease transmission.

While the advent of cooled transported semen has fundamentally changed the horse breeding industry, allowing mare owners access to stallions best suited for their mares based on genetic compatibility rather than geographical convenience, it is not without problems. Stallion management and semen processing in many cases is performed at “home farms” where perhaps there is less experience or expertise in proper semen handling techniques and mare management is now the responsibility of local vets or owners that may not be experienced in reproductive management of mares.

Over the past several years there have been significant occurrences of venereal transmitted equine disease in the US that have raised awareness of the importance of health testing of stallions in the breeding population.

In 2008 a stallion that was being routinely screened for T. equigenitalis, a bacterium that causes contagious equine metritis, prior to collection of semen for export was found to be an asymptomatic carrier of this venereal disease. Since the US is considered to be free of CEM, all breeding animals entering the US have to undergo testing for the disease during mandatory quarantine at an approved facility prior to being released into the general domestic horse population. In the 2008/2009 occurrence in the US, 23 carrier stallions and 5 infected mares were identified during an intense trace back study that identified a single imported stallion from Europe in 2004 as the source. Although most effectively spread in natural mating populations, most all of the stallions in this occurrence were not bred naturally and were infected via lateral transmission from stallion to stallion by exposure to contaminated fomites (collection equipment, personnel, etc) at semen collection facilities. It was also concluded that some of the positive mares became infected following artificial insemination with transported cooled semen from a carrier stallion.

Equine Viral Arteritis (EVA) is an acute, contagious disease of horses caused by the equine arteritis virus (EAV). The virus is spread primarily via the respiratory route and is rarely fatal to adult horses but in some cases may cause abortion in pregnant mares or be fatal to very young foals. Of particular concern to semen production centers is that stallions are often asymptomatic after primary exposure and become carriers of the virus in their reproductive tracts. The stallions may harbor and continuously shed virus in their semen. The virus survives quite well in cooled or frozen semen and can therefore cause exposure to mares that are inseminated with infective semen. Most of the mares exposed this way will seroconvert and may shed the virus in a nasal discharge after insemination. This is generally not a significant problem for the mare and presence of the virus does not appear to have a negative effect on fertility or cause endometritis. However, there is a significant risk of abortion to pregnant mares or young foals that may be exposed to the virus via the respiratory route from the inseminated mare that may be shedding active virus through a nasal discharge.

Interestingly, the United States does not have a negative EVA requirement for stallions or frozen semen entering the country and there have been several documented incidences of EVA positive frozen semen being imported over the last 25 years.

In 2004 there was a severe outbreak of EVA in a relatively naïve Quarter horse population in the western US. An asymptomatic carrier stallion was being collected and his cooled semen shipped to farms in several states for AI of unvaccinated mares. The outbreak caused clinical disease and abortions at several locations and had a significant financial impact. This outbreak could have been avoided had there been a requirement for EVA testing and/or vaccination for domestic distribution of cooled or frozen semen. As a result, a few of those western states have instituted requirements for EVA testing of stallions whose semen will be brought into the state. With the apparent increase in the reported occurrences of EVA worldwide perhaps more states should institute a program of EVA vaccination and testing.

The American Association of Equine Practitioners (AAEP) has published “Biosecurity Guidelines for Control of Venereally Transmitted Diseases” that provide a more thorough set of recommendations for EVA and other potential venereal diseases.

As mentioned earlier, there currently are no universally accepted standards for the production of quality semen by AI centers in North America. A European based organization called the World Breeding Federation of SportHorses (WBFSH) several years ago published recommended guidelines for semen production and quality standards for its member breeding stations. The details of these guidelines can be found here.

Member laboratories of the Select Breeders Affiliate Laboratory Network have also agreed to follow a set of guidelines for quality standards for frozen semen. 

AI with frozen semen has been practiced extensively in the dairy industry in this country since the 1950’s. An organization called the National Association of Animal Breeders (NAAB) developed a program for voluntary monitoring of semen collection and production facilities. A subsidiary of NAAB called Certified Semen Services (CSS) was formed in 1976 to provide oversight and monitoring of CSS-Certified facilities that produced and sold frozen cattle semen. This is a voluntary program that bull studs subscribe to. CSS provides independent quality assurance for these facilities and monitors health testing of donor bulls, housing conditions, sanitary protocols, identification and inventory verification and beginning in 2011, semen quality control auditing. Essentially, dairymen that are purchasing frozen semen for use in their herds will look for CSS Certified semen for the security that comes from the independent oversight provided.

Perhaps it is time for the equine industry to consider such a voluntary program of oversight to provide similar assurances for mare owners.

In the dairy industry young bulls are fertility tested by inseminating thousands of cows with their frozen semen to establish the level of fertility that can be expected before the frozen semen is sold on the commercial market. Furthermore, the difference between a low fertility bull and a high fertility bull due to genetic selection for fertility and “freezability” over many decades is just a few percentage points per cycle. This is vastly different from the situation for stallions where most will never breed “thousands” of mares over the course of a lifetime to demonstrate a reliable estimate of expected fertility, let alone before the semen is marketed. Additionally, there is a huge variation in pregnancy rates between high and low fertility stallions. For this reason, in my opinion, semen should be used as part of a guaranteed breeding contract rather than as a commodity like bull semen. So for mare owners, an independent program to provide oversight for disease prevention and some standards for semen quality would seem appropriate.

Testing for semen quality is not perfect (see FAQ: Can't post-thaw motility vary with the laboratory performing the analysis) and there will always be some unscrupulous breeders that try to cheat the system but the approach of no regulation is dangerous and when there are no guarantees of pregnancy (as is the case with a lot of imported frozen semen), all the risk is placed on the mare owners. The only approach for mare owners is to know who you are doing business with and deal only with reputable sources.

Of course it is in everyone’s best interest to do the best possible work to ensure that mares get pregnant quickly and efficiently and there are clearly financial incentives on the part of the stallion owner in any agreement that involves a pregnancy guarantee of any kind. Most problems are not the result of intentional bad management but rather lack of knowledge or education and experience on the part of the personnel involved on either the stallion or mare end.

EU type licensing of semen collection and AI stations that required professional supervision, mandatory health testing and some level of demonstrated technical proficiency would theoretically improve the overall results and efficiency of breeding programs in the US and better protect the industry against diseases that could be efficiently and rapidly spread through transported semen.

However, we Americans are very independent minded and resist regulations of most kind and this type of requirement would undoubtedly increase the costs for stallion owners. Whether it is a voluntary oversight program such as that provided by CSS in the cattle industry or a mandatory program provided by a governmental regulatory body similar to the EU licensing program or nothing at all is a topic of controversy among breeders and veterinarians. My purpose with this article was to stimulate your thinking on the subject. Please share your opinions and contribute to the dialogue.

Tags: Frozen Semen, Regulations