Effects of Sodium Dodecyl Sulphate on Post-thaw Dog Semen Quality during in vitro Incubation at 39°C and 22°C

Sodium dodecyl sulphate, N-octyl β-D glucopyranoside and 4-methoxy phenyl β-D glucopyranoside effect on post-thaw sperm motion and viability traits of Murrah buffalo (Bubalus bubalis) bulls

Sodium Dodecyl Sulphate (SDS), N-Octyl β-D Glucopyranoside (NOG), 4-Methoxy Phenyl β-D Glucopyranoside (4-MPG) as ice recrystallization inhibitors were added to Tris Egg Yolk Glycerol (TEYG) semen extender for cryopreservation of semen of buffalo bulls. Post-thaw sperm motion and viability traits were evaluated. Pilot study involved six semen ejaculates (2 ejaculates/bull, from three bulls); second experiment was conducted using twenty seven semen ejaculates (9 ejaculates/bull, from 3 bulls) and in third experiment three semen ejaculates (one bull) were used. Eight concentrations of SDS (2, 1, 0.5, 0.25, 0.15, 0.125, 0.0625 and 0.0312%), twelve concentrations of NOG (33, 22, 11, 5.5, 2.5, 0.75, 0.5, 0.25, 0.125, 0.0625, 0.03125 and 0.0156 mM), and, eleven concentrations of 4-MPG (220, 165, 110, 55, 50, 25, 12.5, 6.25, 3.125, 1.56 and 0.78 mM) were supplemented in TEYG semen extender to evaluate the post-thaw sperm motility and viability traits. Computer Assisted Sperm Analysis (CASA) was used to measure the kinetic and functional parameters for sperm motion traits, Hypo Osmotic Swelling Test (HOST) for sperm plasma membrane integrity, Eosin Nigrosin staining for viability and Rose Bengal staining for sperm abnormalities for all the experiments except for pilot study where only Total Motility (TM) and Rapid Progressive Motility (RP) were evaluated. Three freezing protocols; i) Normal P24 (freezing rate of -30 °C min^-1 from 4 °C to -15 °C; -40 °C min^-1 from -15 °C to -60 °C; and -50 °C min^-1 from -60 °C to -140 °C; and then plunged in liquid Nitrogen at -196 °C); ii) Moderate P25 (freezing rate of -30 °C min^-1 from 4 °C to -15 °C; -50 °C min^-1 from -15 °C to -60 °C; and -50 °C min^-1 from -60 °C to -140 °C; and then plunged in liquid Nitrogen at -196 °C); and iii) Rapid P26 (freezing rate of -30 °C min^-1 from 4 °C to -15 °C; -60 °C min^-1 from -15 °C to -60 °C; and -50 °C min^-1 from -60 °C to -140 °C; and then plunged in liquid Nitrogen at -196 °C) were evaluated using SDS 0.125% in TEYG semen extender. SDS ≤0.125%, NOG ≤0.0625 mM and 4-MPG ≤ 3.125 mM in TEYG buffalo semen extender improved significantly (p < .05) the kinetic and functional parameters as compared to the other Ice Recrystallization Inhibitors (IRIs) concentrations used for cryopreservation of buffalo bull semen in the pilot study. SDS 0.125% supplementation was the best IRI among all which resulted in improved kinetic and functional parameters of bull semen in second experiment. Conclusion was drawn that buffalo bull semen cryopreservation using sodium dodecyl sulphate, 0.125% as IRI in TEYG semen extender along with freezing protocol P 25 revealed optimum kinetic and functional parameters for post-thaw spermatozoa.

Comparing ethylene glycol with glycerol for cryopreservation of canine semen in egg-yolk TRIS extenders

The objective of this work was to evaluate the possibility of substituting glycerol (G) for ethylene glycol (EG) when cryopreserving dog semen. A total of 15 ejaculates from 13 dogs was pooled into five samples and frozen in egg-yolk Tris extenders with variable ethylene glycol and glycerol concentrations, with or without Equex STM Paste. Two widely used glycerol extenders (Uppsala Equex II and Norwegian) were utilized as controls. Semen quality parameters assessed after thawing were total subjective motility (TSM), computer assisted sperm analysis (CASA), eosin-nigrosin staining, and flow cytometry (FC) after staining with the PI/Fitc-PSA (fluorescein isotiocianate conjugated with the agglutinin of Pisum sativum, PSA) fluorochromes. No advantages were seen in using EG to replace G when freezing dog semen or combining EG and G in the freezing medium. The Uppsala Equex II provided the best overall post-thaw parameters, followed by the egg-yolk Tris experimental extender with 5% EG and Equex STM Paste. The extender with 4% EG produced similar results to the Norwegian extender. High correlations (r>0.98) were obtained between eosin-nigrosin staining and FC, as well as between subjective and computerized motility assessment (r>0.90).

Effects of addition of sodium lauryl sulfate on frozen-thawed canine spermatozoa

The addition of Orvus ES paste (OEP) to extender may be essential for preparing frozen dog semen. The major ingredient of OEP is sodium lauryl sulfate (SLS). In this study, we compared the effect of SLS on frozen dog semen with that of OEP. There were no significant differences between the 2-mg/ml SLS group and OEP group concerning sperm motility, viability and the percentage of viable sperm with intact acrosomes after freeze-thawing. These results suggest that the effectiveness of frozen dog semen extender containing 2 mg/ml of SLS is similar effective to that demonstrated for OEP.

Effects of Equex from different sources on post-thaw survival, longevity and intracellular Ca2+ concentration of dog spermatozoa

The aims of the present study were to compare the effects of two commercial preparations (Equex STM Paste or Equex Pasta), whose active ingredient is sodium dodecyl sulphate (SDS), added to a Tris-egg yolk-based extender, on post-thaw sperm survival and longevity, as well as on the intracellular Ca(2+) concentration of dog spermatozoa during incubation at 38 degrees C. One ejaculate was collected from each of eight dogs. Each ejaculate was centrifuged, the semen plasma discarded, and the sperm pellet rediluted with a Tris-glucose-egg yolk extender containing 3% glycerol (Ext-1) at a sperm concentration of 200 x 10(6) spermatozoa (spz)/ml. The diluted semen was divided in three aliquots of equal volume and allowed to equilibrate for 1h at 4 degrees C. After equilibration, the same volume of three different second extenders was added, respectively, to each of the three aliquots: (A) Ext-2A (same composition as Ext-1 except that it contained 7% glycerol and 1% Equex STM Paste), (B) Ext-2B (same composition as that of Ext-1 except that it contained 7% glycerol and 1% Equex Pasta), and (C) Ext-2 (CONTROL: same composition as that of Ext-1 except that it contained 7% glycerol). Semen samples were packed in 0.5 ml straws and frozen on a rack 4 cm above liquid nitrogen (LN(2)) in a styrofoam box. Thawing was at 70 degrees C for 8s. Sperm motility was evaluated after thawing and at 1 h intervals for 5h at 38 degrees C by subjective examination and by using a CASA system. Plasma membrane integrity and acrosomal status were evaluated at 1, 4 and 7h post-thaw using a triple staining procedure and flow cytometry. Intracellular Ca(2+) concentration of live spermatozoa was evaluated by flow cytometry at 1, 4 and 7h post-thaw after co-loading the sperm cells with the Ca(2+) indicators Fluo 3 AM and Fura Red AM, and with PI. Post-thaw sperm survival and longevity, as well as the quality of the sperm movement, were significantly better (P<0.005) when Ext-2A (containing Equex STM Paste) was used. There was no difference between Ext-2B (containing Equex Pasta) and Ext-2 (CONTROL). The mean intracellular Ca(2+) concentration (arbitrary units) of cryopreserved spermatozoa (range: 0.23+/-0.12 to 1.26+/-0.46) was higher than that of fresh spermatozoa (0.13+/-0.06). When using Ext-2A, the live spermatozoa frequently (P=0.012) appeared divided in two subpopulations, with high (1.26+/-0.46) and low (0.27+/-0.09) intracellular Ca(2+) content, respectively. When using Ext-2B or Ext-2, the live spermatozoa were more frequently seen in a single population with low intracellular Ca(2+) concentration (0.30+/-0.35 and 0.23+/-0.12, for Ext-2B and Ext-2, respectively).

Effects of Equex, one- or two-step dilution, and two freezing and thawing rates on post-thaw survival of dog spermatozoa

The objectives of the present study were to evaluate the effects of adding Equex to a TRIS-extender, diluting the semen in 1 or 2 steps, freezing according to 2 methods, thawing at 2 rates, and the interactions between these treatments, on the post-thaw survival of dog spermatozoa at 38 degrees C. Ten ejaculates were obtained from 8 dogs. Each ejaculate was centrifuged, and the seminal plasma was discarded. Each sperm pellet was diluted with 2 mL of a TRIS-glucose-egg yolk extender containing 3% glycerol (Extender 1 [Ext-1]). Ejaculates were then pooled (9 x 10(9) spermatozoa), and Ext-1 was added to obtain 200 x 10(6) spermatozoa/mL. The semen pool was carefully mixed and divided into aliquots, and processed according to a 2 x 2 x 2 x 2 factorial design to evaluate the effects of 1) adding the same volume of a second TRIS-glucose-egg yolk extender with 7% glycerol that contained (Ext-2-E) or didn't contain (Ext-2) 1% of Equex STM Paste (final concentration of spermatozoa 100 x 10(6) spermatozoa/mL, glycerol 5%, Equex 0% [Ext-2] or 0.5% [Ext-2-E]); 2) diluting the semen in 1 step (adding Ext-2 or Ext-2-E before equilibration) or in 2 steps (adding Ext-2 or Ext-2-E after equilibration, just before the freezing operation); 3) freezing the straws horizontally in a styrofoam box 4 cm above liquid nitrogen (LN2) or by lowering them vertically into a LN2 tank in 3 steps; and 4) thawing at 70 degrees C for 8 sec or at 37 degrees C for 15 sec. A total of 16 treatment combinations were evaluated. Sperm motility was evaluated after thawing and at 1-h intervals during 7 h of incubation at 38 degrees C by subjective examination and by using a CASA-system. Plasma membrane integrity and acrosomal status were evaluated simultaneously at 1, 3 and 6 h post-thaw using a triple fluorescent staining procedure and flow cytometry. The best post-thaw survival and thermoresistance of spermatozoa was obtained when Equex was present in the extender (P<0.0001); the semen dilution was performed in 2 steps instead of 1 (P<0.0001); the freezing was carried out using the box instead of the tank (P<0.05); and the straws were thawed at 70 degrees C for 8 sec instead of at 37 degrees C for 15 sec (P<0.0001).