Freezability of Andalusian donkey (Equus asinus) spermatozoa: effect of extenders and permeating cryoprotectants

Freezability of Andalusian donkey (Equus asinus) spermatozoa: effect of extenders and permeating cryoprotectants

D. Acha, M. Hidalgo, I. Ortiz, M. J. Gálvez, J. J. Carrasco, V. Gómez-Arrones and J. Dorado

Veterinary Reproduction Group, Department of Animal Medicine and Surgery, Faculty of Veterinary Medicine, University of Cordoba, Campus de Rabanales (Edif. Hospital Clínico Veterinario), Ctra. Madrid-Cádiz, km 396, 14071 Córdoba, Spain; Equine Reproduction Center, Centro de Selección y Reproducción Animal, (CENSYRA-Extremadura Government), Camino Santa Engracia, S/N (Estación Pecuaria), 06007 Badajoz, Spain

The aim of this study was to compare the effect of two semen extenders and four permeating cryoprotectants on post-thaw sperm quality of Andalusian donkeys. First, 32 ejaculates were pooled, split and frozen in either Gent B or INRA 96 with egg yolk and glycerol. Second, 12 pooled semen samples were simultaneously frozen in Gent B (glycerol) or Gent A containing ethylene glycol (EG; 1 or 1.5%) or dimethyl sulfoxide (DMSO; 1.5 or 2%). Finally, nine pooled samples were simultaneously cryopreserved in Gent A containing 1% EG (as control), dimethylformamide (DMFA; 1 or 2.5%) or a combination of 1% EG and 1.5% DMFA. Gent B yielded a higher (P < 0.01) post-thaw sperm motility than modified INRA96. EG 1% increased the sperm membrane integrity (P < 0.001), whereas DMSO affected sperm motility and membrane integrity (P < 0.001). DMFA 2.5% yielded higher (P < 0.001) values for sperm motility and membrane integrity. We concluded that Gent B improves in vitro post-thaw sperm quality of donkey spermatozoa, but the replacement of glycerol with 1% EG or 2.5% DMFA increased sperm protection against cryodamage. The use of DMSO for freezing donkey semen was unsuccessful and a toxic effect is suspected. These extenders should be included in the pre-freeze test for each donkey.

doi: 10.1071/RD14449