Selection of frozen - thawed stallion semen by microfluidic technology.

The use of microfluidic technology is increasing in artificial reproduction technologies (ART): with a small amount of semen, it allows for the selection of sperm with the best characteristics of kinetics, morphology, and chromatin integrity. The ZyMot Multi (850 μL) is the most popular device of the ZyMot Fertility, Inc. To date it was proven to be a valid instrument for sperm selection for in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) in men. The aim of this study was to test the efficacy of the ZyMot Multi (850 μL) for stallion semen. Frozen - thawed semen from 15 stallions that was previously classified as being of "good fertility" (GF; n = 8; pregnancy rate ≥40%) and "poor fertility" (PF; n = 7; pregnancy rate <20%), respectively, was used. Each ejaculate was assessed before and after microfluid recovery for kinetics (CASA), membrane integrity (SIBR14/PI), membrane functionality (HOS test), acrosome integrity (Spermac stain kit), morphology (Spermac stain kit), mitochondrial membrane potential (JC - 1) and chromatin integrity (aniline blue). Sperm concentration was reduced after sperm recovery in both groups, but more markedly in frozen-thawed semen of PF stallions (P<0.05). Microfluid recovery increased total motility, membrane integrity, membrane functionality and mitochondrial membrane potential. While there was a significant increase in the percentage of progressively motile sperm after sperm microfluid recovery, there was a decrease in DAP, DSL, VAP, VSL, LIN, WOB and ALH (P<0.05). A slight increase (P<0.05) was detected in BCF. The present results suggest that the ZyMot Multi (850 μL) device selects a specific sperm population from any stallion ejaculate with motile sperm and could therefore be a valid tool for in vitro testing with the aim to predict the fertility of frozen-thawed stallion semen.