Comparison of two sperm freezing protocols of Colombian Criollo horses: preliminary results

Abstract

The equine industry is an essential source of job and income worldwide. The use of artificial insemi-nation (AI) with frozen semen is an opportunity to continue disseminating the Colombian Criollo horse. Seminal cryopreservation studies in Colombian Criollo horses are limited, and there is no pre-vious knowledge in deleterious changes induced by the cryopreservation process on the chromatin integrity of the spermatic cells. The present study aimed to verify the effect of the modified-INRA 82 and Botucrio® extenders on sperm kinematics, chromatin integrity, and morphology of cryopreserved Colombian Criollo sperm. Five ejaculates of five stallions were obtained, split into two samples, and frozen with two different extenders (modified-INRA 82 and Botucrio) and cooling curves. After freezing, samples were analysed with the CASA system. Sperm morphology, chromatin integrity, hypoosmotic, and thermoresistance tests were performed. Data were analysed by MANOVA (para-metrical variables) and Kruskal Wallis (non-parametrical variables) with SAS Studio ® software. Statistically significant differences (P≤0.05) were found for the progressive motility (14 ± 5 and 27 ± 13), and chromatin integrity (64 ± 3 and 69 ± 5) for modified-INRA 82 and Botucrio, respectively. Botucrio samples presented higher total motility at 30, 60, 90, 120, and 150 min and progressive motility at 60, 90, 120 min in thermoresistance test than modified-INRA 82. Botucrio and modified-INRA 82, are capable to conserve effectively equine semen from Colombian Criollo horses. However, Botucrio permitted an improved kinematics and higher chromatin integrity than modified-INRA 82.

Keywords

• cryopreservation
• dimethylformamide
• equine
• freezing-thaw
• glycerol
• semen