Characterisation of movement pattern and velocities of stallion spermatozoa depending on donor, season and cryopreservation

Semen quality and freezability analysis during breeding and non-breeding seasons in heavy draft stallions in southern Chile

The aim of this study was to evaluate seasonal changes in basic parameters of sperm quality and freezability behaviour of ejaculates from 10 fertile heavy draft stallions. A total of 140 ejaculates were collected, processed and evaluated during both the breeding (September-November) and non-breeding seasons (April-June). Fresh semen was evaluated for volume, concentration, total spermatozoa per ejaculate, plasma membrane integrity and total sperm motility. Cryopreserved samples were evaluated for plasma membrane integrity and sperm motility by the CASA system, and for the freezability index (FI), which was defined as the decreased ratio of viability after freezing-thawing. In fresh ejaculates, only viability showed significantly higher values in the breeding than in the non-breeding season (64.0% ± 15.0% vs. 58.6% ± 12.0%, respectively; p < .05). The sperm post-thawing analysis of viability and total motility parameters showed no significant changes linked to the season. However, the FI analysis showed that the ejaculates collected in the non-breeding season had higher cryoresistance characteristics than those collected in the breeding season. Results suggest that the presence of some cryoprotective factor/s in heavy draft horse ejaculates could be modulated by seasonality, with higher protective effects in the non-breeding season.

Comparison of the Effects of Five Semen Extenders on the Quality of Frozen-Thawed Equine Epididymal Sperm

Cryopreservation of epididymal sperm allows the saving of genetic material in case of unexpected death or emergency castration. The aim of the present study was the comparison of five different combinations of extenders commercially available for equine frozen semen processing for cryopreservation of epididymal sperm. Epididymal sperm were harvested from gonads of 10 healthy stallions after routine castration by retrograde flush technique. Then, samples were split and diluted with (1) INRA96 + INRA Freeze, (2) BotuSemen + BotuCRIO, (3) EquiPlus + Gent Freeze, (4) EquiPlus + EquiPlus Freeze, and (5) Gent + Gent Freeze. Extenders 1 and 2 showed higher values for total and progressive motility after thawing compared with extender 4 (P < .05). Extender 3 was in between 1 and 2 (P > .05), and extender 5 resulted in the lowest values (P < .05). The subpopulation of viable frozen-thawed sperm with high mitochondrial membrane potential and low intracellular calcium content was higher using extender 1 compared with extenders 3, 4, and 5 (P < .05) and higher in extender 2 compared with extenders 4 and 5 immediately after thawing (P < .05). After 1 hour of incubation, this subpopulation yielded the highest values in extender 2 (P < .05). Immediately after thawing, extender 1 yielded higher values for percentage of DFI and mean DFI than extenders 3, 4, and 5 (P < .05). Following 1 hour of incubation after thawing, sperm processed with extender 1 resulted in the highest values for percentage of DFI and mean DFI (P < .05). Using extender 2, mean DFI values were lower than those in extender 1 and higher than the extenders 3, 4, and 5 (P < .05). The study revealed that according to the examined sperm quality parameters, freezing extenders (extender 1, extender 2) using low concentrations of glycerol either combined with or without methylformamide were beneficial for cryopreservation of stallion epididymal sperm. For processing of stallion epididymal sperm, an extender containing milk proteins (extenders 1-4) for initial dilution after sperm harvesting is preferable to an extender including egg yolk (extender 5).

Effect of Cholesterol and Equex-STM Addition to an Egg Yolk Extender on Pure Spanish Stallion Cryopreserved Sperm

Cholesterol and Equex-STM are frequently added to different commercial and experimental extenders improving postthawing sperm quality. Doses of 125-150 mM of cholesterol from pig liver and 0.5-0.7% of Equex-STM were evaluated in a standard eggyolk extender (Martin et al., 1979). Six ejaculates per stallion from six pure Spanish stallions (6-8 years old) were collected in Martin's extender (B) and different mixtures of 125 mM-0.5% (I), 125 mM-0.7% (II), 150 mM-0.5% (III), and 150 mM-0.7% (IV) were added to original Martin's extender. Samples were frozen in 0.5 mL straws (100 × 10(6) spermatozoa) and thawed (21 s., 37°C water bath). After thawing the following parameters were evaluated: viability (V), motility (computer assisted sperm analysis, CASA; % nonprogressive NP; % progressive MP), hipoosmotic swelling test (HOST), acrosome integrity (A), fluorescence test (FL), and resistance test (RT). Sperm quality was significantly affected by stallion (in the parameters V, VI, NP, MP, HOST, A, FL, and RT), extraction (VI, NP, MP, HOST, A, and FL), and the different combinations of Equex-STM-cholesterol (FL). We concluded that 0.5% of Equex-STM mixed with 125 mM of cholesterol has obtained better sperm quality results than those of original Martin's extender, showing a simple and economic improvement of this home-made practical seminal extender.