Colloidal Centrifugation as a Method of Sperm Selection Prior to Cryopres-ervation with Glycerol in Canines

Abstract

Background: The ejaculate of the dog has three fractions, the first and third containing prostatic fluid that is harmful to cryopreservation, and the second rich in sperm. Obtaining only the second fraction of the ejaculate is complicated; therefore, colloidal centrifugation was evaluated as a sperm selection method, plus the addition of glycerol in three concentrations 4, 6 and 8 % as cryoprotector. 

Methods: The study was conducted at the University of Cuenca-Ecuador, 72 seminal samples from 6 crossbreed dogs were evaluated. Each sample was divided into 2 aliquots, the first for Group 1 (conventional centrifugation) and the other Group 2 (colloidal centrifugation), once centrifuged each aliquot was sub-divided into three and 4, 6 and 8 % of glycerol were added. Three spermatic evaluations were carried out (initial, pre and post thawing). 

Results: The sperm concentration after centrifugation was similar between the initial sample (MI) and Group 1 (P > 0.05); in Group 2 less sperm was observed (P < 0.05). When assessing the progressive individual motility (MIP) pre freezing, it was observed that the sperm of the Group 1 reduced 30 % its motility in relation to the sample MI and that of Group 2. Post thawing MIP within the groups with different concentrations of glycerol (4, 6, 8 %), which previously received centrifugation with Percoll (Group 2) presented statistical difference (P < 0.05). However, the HOS test gave similar percentages.

 Conclusions: It is concluded that colloidal centrifugation, prior to the freezing process, is a technique that allows greater selection and sperm purification.