Differences in preservation of canine chilled semen using different transport containers

In the present study, the effect of three different containers in the preservation of dog chilled semen, during 24, 48 and 72 h was evaluated. Weekly sperm pools of different dogs were obtained, during 10 consecutive weeks. Semen samples were diluted in egg-yolk–Tris–fructose extender and stored in a Styrofoam box, a common Thermos flask and an Equitainer®. Progressive motility, morphology and sperm membrane integrity were examined in semen aliquots taken daily from each container during the 3 days of storage. Additionally, integrity of the acrosome and sperm plasma membranes, determined by PI/Fitc-PSA staining was assessed at 48 and 72 h of storage.At 24 h no differences were observed between the three containers for the evaluated parameters. At 48 h samples kept in the Equitainer® presented a higher progressive motility than samples kept in the Thermos. At 72 h, progressive motility was higher in the Equitainer® than in the other two containers. Only samples kept in the Equitainer® maintained similar levels of progressive motility between 24 and 72 h. Membrane integrity assessed by eosin–nigrosin deteriorated over the 72 h period, whereas functional membrane integrity determined by the hypoosmotic swelling test was independently affected by type of container (the Equitainer® kept a higher percentage of sperm cells with intact membrane) and time of storage (a decrease of membrane integrity between 24 to 72 h). Staining with PI-Fitc-PSA allowed the detection of differences between containers but not between the two studied storage periods (48 and 72 h). The results indicated that the use of the Equitainer® is preferable when transporting chilled dog semen for more than 48 h.