E Kommisrud1,2 1Hedmark University College, Hamar, Norway 2SpermVital AS, Hamar, Norway
To make artificial insemination (AI) an even more valuable breeding method an immobilization technique for spermatozoa has been developed. The technology has successfully been combined with cryopreservation, a necessity for AI in cattle. The idea of immobilizing sperm cells arised to improve fertility results and make AI more flexible concerning timing. The company SpermVital AS was established to commercialize the results from R&D, and the product has been launched in several cattle AI markets. Research is performed by the company, including lab-trials and smaller AI trials to further improve the product and verify and document the progress. Thus, the company is having improved versions in the pipeline, and is also aiming for application in several species, including humans. Cell immobilization is used for prolonging the shelf-life of spermatozoa both prior to and after AI. The technology has been demonstrated on liquid semen as well as on cryopreserved semen, both in vitro and in vivo. The SpermVital technology has successfully been applied in the bovine, ovine, equine and porcine. The sperm cells are embedded in a homogenous gel network made of calcium alginate gel, representing a fundamentally different approach than previous reported encapsulation techniques leaving the cells in a liquid core surrounded by a membrane. Upon AI or application in artificial media, the gel will gradually dissolve, releasing sperm cells over a prolonged period. In vitro models mimicking uterus in vivo conditions have demonstrated that gels with immobilized sperm may dissolve both fast and slow, depending on the alginate gel and the media composition. Several studies have been conducted to determine dissolving time in relation to prolonged survival of both immobilized and released sperm cells. Quality control in vitro includes e.g. viability, acrosome integrity and DNA integrity. In vivo AI field trials, conducted on several thousand heifers and cows demonstrated that immobilized spermatozoa increase fertility in the Holstein breed, whereas in the highly fertile Norwegian Red double inseminations with ordinary processed semen can be replaced by one single insemination with immobilized semen obtaining equal pregnancy rates. Thus, several AI trials in cattle have indicated that the SpermVital semen is competitive with, or superior to, traditionally preserved semen, and that the timing of AI is less critical using immobilized semen.