Freeze-drying (FD) is a new and alternative method to preserve spermatozoa in refrigeration or at room temperature. Suitable protection is required to maintain the sperm DNA integrity during the whole process and storage. The aim of this study was to examine the effect of rosmarinic acid and storage temperature on the DNA integrity of freeze-dried ram sperm. In addition, we evaluated the in vitro developmental ability to the blastocyst stage of oocytes injected with freeze-dried sperm. Ram sperm was freeze-dried in basic medium and in this medium supplemented with 105 µM rosmarinic acid. The vials were stored for 1 year at 4 °C and at room temperature. Frozen sperm was used as control. After rehydration, sperm DNA damage was evaluated, observing that the percentage of spermatozoa with DNA damage decreased significantly in the presence of rosmarinic acid, without differences between the two storage temperatures. Moreover, no differences were observed between the freeze-dried group and the frozen-thawed group in terms of blastocyst formation rate. We proved for the first time that ovine spermatozoa can be lyophilized effectively, stored at room temperature for long term, reconstituted and further injected into oocytes with initial embryo development.

A B S T R A C TFreeze-drying (FD) technique has been applied as an alternative technology to preserve gene resources to allow simple sperm preservation and shipment at 4°C. Nevertheless, DNA sperm might be damaged by mechanical or oxidative stress throughout FD procedure. Therefore, suitable protection to maintain DNA integrity is required. The aim of this study was to determine the effect of rosmarinic acid (RA) as an antioxidant and two chelating agents (EGTA and EDTA) on the DNA integrity of freeze-dried rabbit sperm after storage of the samples at 4°C and room temperature for 8 months. Rabbit sperm were freeze-dried in basic medium (10 mM Tris-HCl buffer and 50 mM NaCl) supplemented with 50 mM EGTA (1), 50 mM EGTA plus 105 μM RA (2), 50 mM EDTA (3) or 50 mM EDTA plus 105 μM RA (4). Semen samples were kept at 4°C and room temperature during 8 months. After rehydration, DNA integrity was evaluated with Sperm Chromatin Dispersion test observing that DNA fragmentation was higher when semen samples were freeze-dried with EGTA (10.9%) than with EDTA (4.1%) (p < 0.01). Furthermore, RA acted better under adverse conditions and no significant differences were found in temperature storage. Summarizing, FD is a method that can allow simple gene resources preservation among 4°C to 25°C during 8 months and transportation without the need for liquid nitrogen or dry ice. EDTA chelating agent is the most suitable media for freeze-dried rabbit sperm and the addition of RA protects the DNA against the oxidative stress caused during FD procedure. (P. Domingo).Cryobiology xxx (xxxx) xxx-xxx 0011-2240/

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The purpose of this research was to find a suitable protocol to enhance frozen rabbit sperm preservation analysing the role that seminal plasma (SP) plays and the effect of different cryoprotectant agents on sperm quality 0 and 2 h after thawing. Sperm samples were pooled and divided in eight fractions. Four of them were diluted with BotuCrio^® (extender A), INRA 96^® plus 6% glycerol (extender B), 6% N, N-dimethylformamide (extender C) and 6% N-methyl-2-pyrrolidone (extender D), respectively. The other four fractions were centrifuged and the supernatant was discarded in order to eliminate SP. Each sample was then resuspended with extender A, B, C and D. Samples were cooled progressively, loaded into 0.5 ml freezing straws and frozen with liquid nitrogen vapour. Thawing was performed by placing the straws into a bain-marie at 37°C for 21 s. Straws were dried and sperm samples placed into Eppendorf tubes to be analyzed by ISAS software, vitality test, HOS test and acrosome integrity test. The best motility and velocity parameters were obtained by extender A (P &lt; 0.050) even when the motility parameter was compared with previous studies using other diluents. Additionally, sperm quality decreased over incubation time (P &lt; 0.050) and no differences were found in samples processed with or without SP. This research revealed that BotuCrio^® could be used for rabbit sperm cryopreservation and moreover the improvement of the cryopreservation process of rabbit sperm due to the demonstration that SP removing is not required.