The first aliquot (control) was subjected to a slow freezing selleckchem curve previously described for collared peccaries [7]. In this protocol, the aliquot was stored in a water jacket (30 mL) at 27 °C and equilibrated for 240 min to reach 5 °C in a biological oxygen demand (BOD) incubator (Quimis, Diadema, SP, Brazil). At that point, the sample was added to the extender with 6% glycerol (also at 5 °C), which resulted in a final concentration of 3% glycerol

in the extender, and the sample was then evaluated. Finally, the semen aliquot was divided and packed into 0.25 mL or 0.50 mL plastic straws (IMV Technologies; L’Aigle, France) that were placed horizontally in an insulated box for 20 min, at 3 cm above the nitrogen (N2) vapors, and then

plunged into N2 for storage at −196 °C, following a slow FK506 cost freezing rate at −10 °C/min. The second aliquot was cryopreserved following a fast freezing curve described by Silva et al. [35]. Semen aliquot was stored in the water jacket at 27 °C and equilibrated for 40 min to reach 15 °C in a BOD incubator (Quimis, Diadema, SP, Brazil). Further, BOD incubator was adjusted to establish at 5 °C for 30 min. Then, the glycerol addition and package was conducted as described for the first aliquot. However, the straws were placed at 5 cm above the N2 vapors for 5 min, and then finally plunged into N2 at −196 °C for storage, following a fast freezing rate at −40 °C/min. In both groups, the digital thermometer of the BOD incubator monitored the cooling rate up to 5 °C. Further, the Thymidylate synthase probe of an appropriate thermometer was inserted into the insulated box containing N2 vapors in order to monitor the cooling rates. After 1 week, three 0.25 mL and 0.50 mL straws derived from each of two freezing curves were thawed on a water bath, at 37 °C/1 min, and others at 70 °C/8 s, following a further 30 s at 37 °C. The semen was immediately evaluated, as per the same parameters reported for fresh semen and also for kinematic parameters of sperm motility by computer-assisted semen analysis – CASA, which will be described later. The thawed semen was

diluted in ACP-116c® on a proportion of one part semen to one part extender; then, it was evaluated by CASA, as described by Verstegen et al. [37]. Samples (10 μL) were placed in a Makler chamber, allowed to settle for 1 min and maintained at 38 °C. They were then examined in a phase contrast microcopy system with stroboscopic illumination, coupled with a video camera adapted to the Sperm Class Analyzer (SCA Version 3.2.0; Microptic s.l., Barcelona, Spain). The settings of the instrument were adjusted according to the boar semen, including temperature, 37 °C; frame rate, 25 frames/s; minimum contrast, 75; straightness threshold, 45%; low-velocity average pathway (VAP) cut-off, 10; and medium VAP cut-off, 25. Three independent and nonconsecutive microscopic fields were randomly selected and scanned.