Diferentes diluentes sobre a motilidade e integridade de membrana plasmática após o congelamento e descongelamento de sêmen ovino

The influence at the progressive motility and post-thawing plasmatic membrane integrity of different extenders (Tris-Yolk-based, Tris-Yolk/Skim Milk-based and Skim Milk-based) was studied in rams frozen semen, using a split-sample technique. The semen was obtained from four Santa Ines located in the district Campos dos Goytacazes, Rio de Janeiro, Brazil. A total of 8 semen collections per ram made possible 672 observations, i.e. 32 semen collections/ 3 semen extenders / 7 observations steps. The progressive motility was determined in the cool semen (Mpi) and after dilution with fraction A of extender (Mp1), a 2-hour balance period (Mp2), dilution in fraction B (Mp3), a 14-hour balance period (Mp4), semen exposure to N2-liquid vapor (Mp5) and post-thawing (Mp6). The sperm plasmatic membrane integrity was determined by employing fluorochromes carboxyfluorescein diacetate and propidium iodide at post-thawing (Mp6). Tris-Yolk-extender showed a Tris-Yolk/Skim Milk- and Skim Milk-extenders superior performance on recovering the post-thawing progressive motility. The rams presented the highest post-thawing sperm membrane integrity when the semen was frozen in Skim Milk-extender, in comparison to the Tris-Yolk and Tris-Yolk/Skim Milk-extenders. Concluding, it is necessary to elucidate the protection underlying mechanism conferred by the extenders studied over the investigated sperm parameters, given the finding of different extenders specificities on protecting motility and sperm integrity.