The SpermVital technology comprises embedding of spermatozoa within an alginate gel to facilitate release of sperm cells over a prolonged period in utero after AI. The aim of this study was to examine whether the survival time of spermatozoa is extended when applying this immobilization technology in combination with cryopreservation. Sperm cell survival (acrosome and plasma membrane integrity) was studied in vitro for 48 hr at physiological temperature. One dose of SpermVital (SV) semen was compared with single doses of Biladyl (B) processed semen as well as double doses of B (B double). B double was obtained by adding a second B dose the following day, thereby mimicking double AI. Furthermore, reproductive performance applying single early timed AI (TAI) with SV following oestrus synchronization was studied in a field trial. Double insemination (TAI on two consecutive days) with B semen served as control. Number of acrosome-intact live sperm cells decreased over time in vitro for all treatments (p < .05). There was no difference between SV sperm cell survival and B double after 24 hr (p > .05). However, after 48 hr, SV sperm cell survival was higher than B double (p < .05). Moreover, multivariate analysis showed that the outcome of single early TAI with SV was not significantly different from B double (p > .05). Likelihood of pregnancy and calving in the heifer group was higher than in the cow group (p < .05). These results imply that spermatozoa immobilized in alginate gel have prolonged survival.

Development of new semen cryopreservation techniques improving sperm survival and ensuring availability of viable spermatozoa for a prolonged time-period after AI is promising tools to reduce sensitivity of timing of AI and enhance overall fertility. The SpermVital technology utilizes immobilization of bull spermatozoa in a solid network of alginate gel prior to freezing, which will provide a gradual release of spermatozoa after AI. The objective of this study was to compare post-thaw sperm quality and in vitro sperm survival over time of Norwegian Red bull semen processed by the SpermVital (SV) technology, the first commercialized production line of SpermVital (C) and by conventional procedure applying Biladyl extender (B). Post-thaw sperm motility was not significantly different between SV, C and B semen (p > .05). However, sperm viability and acrosome intactness were higher for SV than C and B semen (p < .05). Small differences in DNA quality were observed (p < .05). Sperm viability after storage in uterus ex vivo was higher for SV than for C semen (p < .05). Furthermore, sperm survival in vitro over time at physiological temperature was significantly higher for SV semen than C semen as well as B semen during the incubation period of 48 hr (p < .05). In conclusion, the SpermVital technology is improved and is more efficient in conserving post-thaw sperm quality and results in higher sperm viability over time in vitro for SV than for C and B semen.