A typical inverted U-shaped relationship exists between the cell survival and freezing rates [25]. Therefore, an optimum freezing rate should be slow enough to prevent intracellular ice formation and fast enough to minimize the osmotic shock [26]. In general, it is expected that slow freezing rates result

in the dehydration of cells to compensate for the greater extracellular salt concentration due to ice formation at sub-zero temperatures. Consequently, the intracellular salt concentration increases lead to osmotic shock (solution effect). However, rapid freezing rates would result in cells that do not have sufficient time to dehydrate, leading to intracellular ice formation Epacadostat concentration upon freezing [4]. Straws volume may also affect the semen quality, once the surface-to-volume ratio influences the velocity of latent heat dissipation, affecting the sperm thawing procedure [33]. For swine, the domestic animal closely related to the peccaries [9], the type of package used to freeze–thaw semen usually affects sperm motility and viability [6]; but, by now, only 0.25 mL straws were used for freezing the semen of collared peccaries [7], [8] and [34]. VX-765 manufacturer The objective of this study was to verify the effect of different freezing curves, straw sizes, and thawing rates in order to improve the protocol for collared

peccary semen cryopreservation. The ethics committee of the UFERSA has approved the experimental protocols as well as the animal care procedures adopted (Process no. 23091.0253/114). The reagents used in the present study were obtained from Sigma–Aldrich (St. Louis, MO, United States). A total of eight sexually mature male collared peccaries, aged 40.7 ± 1.6 months with a weight of 22.5 ± 2.8 kg were included in the study. The animals belonged to the Centre of Multiplication of Wild Animals from UFERSA, located in northeast Brazil (Mossoró, RN, Brazil; 5° 100′ S, 37° 100′ W). The region is subject

to a typical semi-arid climate with an average annual temperature of 27 °C. The animals were isolated Sitaxentan from the females for a period of six months prior to the commencement of the study and were kept under a 12 h natural photoperiod. Subsequently, they were divided into groups of four and five animals and maintained outdoors in paddocks (20 × 3 m) with a covered area measuring 3 × 3 m. The animals were fed on a diet of sow food and fruits, and water was provided ad libitum. The animals were kept in fasting condition for 12 h prior to the start of the experiments. They were then physically restrained using a hand net and anesthetized using intravenous administration of propofol (Propovan®, Cristalia, Fortaleza, Brazil), given as a bolus (5 mg/kg) [36]. When the animal showed signs of awakening, additional propofol (approximately 1.25 mg/kg) was given to prolong the anesthesia.