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Canine semen cryoconservation was used since 1969, and this process is still nowadays in progress. This review aims to have an overview of two factors leading to a successful freezing–thawing semen. The success and efficiency of freezing process can be measured by the post‐thawing sperm mobility. The first factor is the best extender used as a cryoprotectant to have a similar osmolarity and pH compared to the seminal plasma to enable sperm survival. Historically, chicken egg yolk was used since 1940, but due to microbial risks and to the presence of granules (which interfere with counting dead spermatozoa and inhibits a spermatozoal respiration), despite these disadvantages, egg yolk is considered an excellent cryoprotectant for sperm of different animal species. The low‐density lipoproteins (LDL), contained in EY, when used at a concentration of 6% in a freezing medium associated with 20 mM of glutamine, show a mobility up to 54.5%, which is the best combination found. However, the sperm protection mechanism by LDL during freezing–thawing process only begins to be decrypted. But extraction protocols of LDL are not efficient for an industrial use. Therefore, egg yolk plasma is used within liquid or lyophilized state, and offering similar efficiency as the 6% LDL middle. The equilibration step, in which the diluted sperm is placed for a variable period of time at a temperature of +4°C, before freezing it. The studies show that 6 hr is the optimal duration for the canine sperm equilibration. The future of canine sperm cryopreservation is expected in liposome use and synthetic substances, which mimics LDL role. [ABSTRACT FROM AUTHOR]

Contents: The use of artificial insemination in cattle breeding has evolved to global extent, and insemination doses are often shipped via air transport which requires strict radiation‐based examinations. For the determination of effect of non‐ionizing radiation (NIR), to which are beings frequently exposed due to protection of airport or cultural event security, freshly ejaculated and cryopreserved bovine spermatozoa were used as experimental model. Following radiation with hand‐held metal detector in various exposition times (0, 10 s, 15, 30 and 60 min—groups FR, FR10, FR15, FR30 and FR60) the spermatozoa underwent motility and DNA fragmentation analyses. Study on cryoconserved semen treated with NIR was performed in time intervals 0, 10 s, 1 and 5 min (insemination doses radiated before cryoconservation—CB, CB10, CB1, CB5; samples radiated after freezing—CA, CA10, CA1 and CA5). Fresh semen and insemination doses radiated after cryoconservation showed significantly lower total and progressive motility. No effect on motility parameters was detected in semen extended with cryopreservative medium and radiated prior to freezing. Surprisingly, NIR showed a potential to stimulate spermatozoa velocity; however, the effect was modulated throughout the post‐thawing incubation. Based on the DNA fragmentation assay, sperm DNA stayed intact. Present study underlines the potential harm of NIR, which is frequently used in everyday life, with overall adverse impact on human and animal reproduction. Current study also points out on interesting short‐term spermatozoa stimulation induced by NIR. [ABSTRACT FROM AUTHOR]