Addition of Equex STM to Extender Improves Post-Thawing Longevity of Collared Peccaries' Sperm

The effect of Equex STM^® paste supplementation on the Tris-extender for collared peccaries' semen cryopreservation was assessed. Semen from 12 mature individuals was obtained by electroejaculation and evaluated for morphology, membrane integrity, osmotic response, and sperm kinetic metrics. Samples were diluted in Tris plus 20% egg yolk and divided into three aliquots. The first aliquot was without any supplementation, the second and third contained 0.5 and 1.0% Equex STM, respectively. The samples were added with 3% glycerol, frozen in liquid nitrogen, thawed, and assessed for the same parameters after a thermal resistance test (TRT) for 120 minutes. Similar values were detected for the different treatments immediately after thawing, except for the amplitude lateral head that was reduced in samples containing Equex (p < 0.05). During TRT, samples containing Equex were more efficient in preserving the sperm motility (at 0.5%: 25.5% ± 4.4%; at 1%: 33.3% ± 6.3%) at 30 minutes, in comparison with the control group (16.6% ± 6.0%), in which sperm motility decreased at 15 minutes (p < 0.05). Moreover, Equex, especially at 0.5% concentration, was able to maintain plasma membrane integrity and sperm motility in all the samples after incubation for 60 minutes. In conclusion, we recommend the addition of Equex STM at 0.5% to the Tris-extender to improve post-thawing sperm longevity in collared peccaries.