Effect of single-layer centrifugation or washing on frozen- thawed donkey semen quality: Do they have the same effect regardless of the quality of the sample?

The aims of this study were to determine the sperm quality of frozen–thawed donkey sperm samples after single-layer centrifugation (SLC) using Androcoll-E in comparison to sperm washing or no centrifugation and to determine if the effect on the sperm quality after SLC or sperm washing depends on the quality of the sample. Frozen–thawed sperm samples from Andalusian donkeys were divided into three aliquots, and they were processed using three different techniques after thawing: uncentrifuged diluted control (UDC), sperm washing (SW), and SLC. Afterward, sperm quality index was estimated by integrating all parameters (total and progressive sperm motility, membrane integrity, and DNA fragmentation) in a single value. The relationship between the sperm quality of thawed UDC samples and the effect on sperm parameters in SW and SLC-selected samples was assessed. Sperm quality index was significantly higher (P < 0.001) in SLC (0.8 � 0.0) samples than that in UDC (0.6 � 0.0) and SW (0.6 � 0.0) samples, regardless of the sperm quality index after thawing of the sperm sample. In conclusion, SLC of frozen–thawed donkey spermatozoa using Androcoll-E-Small can be a suitable procedure for selecting frozen–thawed donkey sperm with better quality, in particular in those samples where an improvement in motility is needed.