A novel semen processing technology based on cell immobilization is used for prolonging the self-life of spermatozoa, both prior to and after insemination. The technology has successfully been applied in bovine, ovine, equine and porcine animals, on liquid semen as well as using cryopreserved semen, both in vitro and in vivo. The sperm cells are embedded in a homogeneous gel network made of calcium alginate gel, representing a fundamentally different approach than previously reported encapsulation techniques leaving the cells in a liquid core surrounded by a membrane. Upon artificial insemination (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 fast or slow, depending on the alginate gel and 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. Further, field trials have demonstrated timing of AI being less critical using immobilized semen.
The immobilization technology on sperm cells was developed to make AI an even more valuable breeding method, by improving fertility results and making AI more flexible. The technology is commercialized by the company SpermVital AS and corresponding products have been launched in several cattle AI markets. Continuous research is performed by the company, having improved versions in the pipeline, and aiming at application in several species, including humans.