Reprod Dom Anim. 2017;1–6. wileyonlinelibrary.com/journal/rda | 1 © 2017 Blackwell Verlag GmbH Received: 11 October 2017 | Accepted: 30 October 2017 DOI: 10.1111/rda.13115 ORIGINAL ARTICLE In vitro studies of Norwegian Red bovine semen immobilized and cryopreserved in alginate solid gel network AH Alm-Kristiansen 1,2 | ER Gaustad 2 | G Bai 2 | FB Standerholen 1,2 | G Klinkenberg 3 | E Kommisrud 1,2 | KE Waterhouse 2 1 Department of Natural Sciences and Technology, Inland Norway University of Applied Sciences, Hamar, Norway 2 SpermVital AS, Hamar, Norway 3 Materialer og Kjemi, SINTEF, Trondheim, Norway Correspondence Anne Hege Alm-Kristiansen, SpermVital AS, Hamar, Norway. Email: ahak@spermvital.com Funding information Regional Research Fund Inland, Norway, Grant/Award Number: 235580 Contents 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. 1 | INTRODUCTION The fertility outcome of bovine AI is a process relying on several factors including appropriate herd management and male and female fertility. Furthermore, accurate timing of AI is of outmost importance for the fertility result (Barth, 1993; DeJarnette et al., 2004). Therefore, it is important to improve and develop semen preservation methods that prolong sperm fertilizing capacity after AI. As a result, timing of insemination would be less critical relative to ovulation by ensuring availability of spermatozoa capable of fertilization for an extended pe- riod. Bull spermatozoa were first encapsulated in poly-l-lysine capsules (Nebel, Bame, Saacke, & Lim, 1985; Nebel, Vishwanath, McMillan, & Saacke, 1993), followed by encapsulation of boar semen in calcium, barium and protamine alginate beads (Faustini, 2011; Faustini, Vigo, Spinaci, Galeati, & Torre, 2012; Torre et al., 2000; Vigo et al., 2002). Furthermore, microencapsulation of human (Herrler, Eisner, Bach, Weissenborn, & Beier, 2006), canine (Shah et al., 2011), bovine and buffalo (Perteghella et al., 2016) spermatozoa has been combined suc- cessfully with cryopreservation. Bull sperm cells can also be immobi- lized in a solid gel network of calcium alginate before cryopreservation by the SpermVital ® technology (Kommisrud, Hofmo, & Klinkenberg, 2008). This technology enables the spermatozoa to be released in the uterus over an extended time-period after AI compared to microen- capsulation where all sperm cells will be released when the capsules are resolved, as well as compared to ordinary cryopreserved liquid semen where all spermatozoa are available immediately after AI. Cryopreservation of spermatozoa cause damage to plasma and acrosomal membranes (Said, Gaglani, & Agarwal, 2010), and acrosome intactness has been considered as a relevant marker for fertilizing ca- pacity (Flesch & Gadella, 2000). Additionally, the sperm DNA must be