The effect of homologous prostatic fluid on the parameters of dog semen extended and frozen in Tris-egg yolk and INRA Freeze: preliminary results

Recent studies showed that the cryoprotector component of egg yolk for the freezing of canine semen is represented by the low density lipoproteins (LDL), while the others components of egg yolk have a number of detrimental effects on the frozen-thawed canine semen. The aim of this study was to compare the effect of a LDL commercial extender used for stallion semen – INRA FreezeÒ (IMV Technologies, L¢Aigle, France) with a standard extender for dog semen containing Tris, fructose, glycerol and 20% egg yolk (TFG-EY). Since there are some conflicting reports concerning the effect of prostatic fluid on sperm function, we also investigated if the effect of post-thaw dilution with autologous prostatic fluid on viability, motility and acrosome status of frozen-thawed canine spermatozoa is correlated with the composition of the extender. Semen was collected from six Beagle dogs and each sperm rich fraction was divided in two parts: one was diluted with INRA FreezeÒ and the other with TFG-EY and frozen with the same protocol. The third fraction of each ejaculate was collected separately, centrifuged at 1118 · g for 10 min and the supernatant was frozen at )18°C until use. For each extender, two straws were thawed: one straw was diluted 1:2 with autologous prostatic fluid, while the other was not diluted at all. Motility (CASA, IVOS; Hamilton Thorne, USA), viability and acrosome status (Guava EasyCyteÒ flow cytom- eter; IMV Technologies, L¢Aigle, France), morphology (Diff-Quick stain) were assessed at 5 min, 1 h and 2 h post-thaw (T0, T1, T2). Statistical analyses were performed with IBM SPSS software (ver. 19 for Windows; IBM, New York, NY, USA). The results are presented as mean values and a p value <0.05 was considered statistically significant. Viability, total and progressive motility and the percentageÓ 2012 Blackwell Verlag GmbH432Abstractsof intact acrosomes were higher (p < 0.05) for the TFG-EY group with or without the addition of the prostatic fluid. The results for motility in the INRA Freeze group were dramatically low compared to the TFG-EY group. There were no significant differences regarding the morphology of fresh and frozen semen for any of the four groups. Addition of prostatic fluid for the TFG-EY group significantly reduced the total and progressive motility at T0, T1 and T2 (p < 0.05), but showed no influence for the INRA Freeze group. This data show that the effect of prostatic fluid regarding motility differs between the two extenders. This may illustrate either an inhibitory effect of some components of the INRA FreezeÒ on the noxious effects of the prostatic fluid or conversely an enhancing effect of the TFG-EY on those. Alternatively, it could be that low values obtained with INRA FreezeÒ did not permit highlighting the effects of prostatic fluid.