Inclusion of catalase in semen extender modulates the post thaw semen quality and oxidative stress profiles in mithun spermatozoa

Present study was designed to assess the effect of catalase on post-thaw semen quality parameters (SQPs), sperm kinematics, antioxidant and oxidative stress profiles and sperm cholesterol efflux in mithun (Bos frontalis). A total of 25 ejaculates were selected based on biophysical parameters and each sample was split into four equal aliquots and diluted (to get final concentration of 60 million spermatozoa per mL) with the TCG extender containing either 0 U/mL, 50 U/mL, 100 U/mL, and 150 U/mL catalase in the Group I, II, III and IV, respectively. Frozen-thawed samples were analysed for motility parameters (progressive forward and in bovine cervical mucus [BCMPT]), kinetic and velocity parameters by computer-assisted sperm analyser (CASA), viability, sperm morphological and nuclear abnormalities, acrosomal integrity, plasma membrane and nuclear integrities, sperm intra-cellular enzymatic leakage and seminal plasma biochemical (sperm cholesterol and oxidative stress markers) profiles. Study revealed an enhancement in viability, acrosomal integrity, plasma membrane integrity, motility (progressive and in cervical mucus), sperm cholesterol content and reduction in sperm morphological and nuclear abnormalities, leakage of intracellular enzymes in Group III. Moreover, intactness of acrosome and biochemical membranes were protected significantly in addition to significant improvement in kinetic and velocity profiles in extender containing 100 U/ml catalase. Correlation analysis revealed that sperm kinetic parameters, SQPs and antioxidant parameters had significant positive correlation with each other whereas these profiles were negatively correlated with sperm morphological abnormalities, enzymatic leakage and lipid peroxidation in catalase treated sperm. The results clearly indicated that inclusion of 100 U/ml catalase holds a clear advantage over control or 50 U/ml or 150 U/ml catalase in cryopreservation of mithun semen. It can be concluded from the present study that catalase supplementation in semen extender can be effectively utilized to reduce the oxidative stress and to improve the post-thaw semen quality in mithun.

Comparative ejaculatory response, fresh and frozen semen quality and fertility to artificial vagina vs electroejaculation method of semen collection in mithun (Bos frontalis) bulls

The study aimed to describe a comparative ejaculatory response, fresh and frozen-thawed semen quality and fertility of semen collected by artificial vagina and electroejaculation in mithun. Experimental bulls were divided into two groups, G-I: young bulls (n = 4; 4-5 years of age) and G-II: older bulls (n = 4; 8-10 years of age). Sixteen ejaculates were collected from each group G-I (AV₁ ) and G-II (AV₂ ) by artificial vagina method (control). Thirty-six ejaculates were collected from the same bulls from each group G-I (EE₁ ) and G-II (EE₂ ) by electroejaculation method (treatment). The study did not reveal any significant (p > 0.05) difference in the ejaculatory responses between EE₁ and EE₂ . Mann-Whitney U test indicated that salivation discomfort sign score was significantly (p < 0.05) higher in EE₁ . Fresh and frozen-thawed semen quality parameters, and motility and velocity profiles recorded by computer-assisted sperm analyser were significantly (p < 0.05) lower in electroejaculation than the artificial vagina. The conception rates (AV₁ vs EE₁ & AV₂ vs EE₂ ) at day 35-45 post insemination were nonsignificantly higher (p > 0.05) in the artificial vagina group. It concluded that, although artificial vagina method has better semen quality, nevertheless, electroejaculation has the potential for semen collection from free-range mithun bulls to incorporate in assisted reproductive technology procedures.

Seminal attributes of Vechur bulls (Bos indicus), the smallest humped dairy cattle

The study was undertaken at Mattupatti semen station to objectively evaluate the seminal attributes of frozenthawed semen of Vechur bulls, the smallest humped dairy cattle in the world, using the computer assisted semen analyzer (CASA) and Flow cytometer. The mean motility and progressive motility of the frozen-thawed semenestimated via CASA was 77.25±9.56 and 64.0±4.21% respectively. Mean values obtained for the sperm kinetic parameters like path velocity (VAP), progressive velocity (VSL), track speed (VCL), lateral head amplitude (ALH),beat cross frequency (BCF), straightness (STR) and linearity (LIN) were 82.56±12.12, 76.22±10.38, 107.77±21.42, 4.39±0.91, 20.87±3.81, 92.37±3.25 and 72.87±6.64% respectively. Flow cytometry analysis of the functional sperm parameters like sperm viability, live sperms with intact acrosome, sperms with normal mitochondrial membranepotential (MMP) and sperms with altered DNA were 81.67±4.55, 76.16±9.76, 82.40±5.61 and 11.75±0.3% respectively. The mean value of the HOS reactive sperms was 71.81±5.71%. Mean values for the length and width of the sperm head, length of mid-piece, tail and overall sperm length measured by computer image analysis was 8.99±0.36, 5.07±0.23, 14.21±0.35, 45.12±1.53 and 68.32±1.41 μm respectively. Study concluded that seminal attributes of Vechur bulls could be estimated with CASA and Flow cytometer and the parameters were comparable to other indigenous, crossbreds and exotic dairy cattle.

Variation in sperm cryosurvival is not modified by replacing the cryoprotectant glycerol with ethylene glycol in bulls

Breed and sire differences in sperm cryosurvival have been noted, with negative implications for sperm cryobanking and assisted reproduction programmes. This study hypothesized that these differences could be modified by using lower molecular weight cryoprotectants. Therefore, the effect of replacing glycerol (GLY) with ethylene glycol (EG) on differential cryosurvival of semen from two Sanga cattle breeds (Mashona vs. Tuli) was determined. Three to five ejaculates were collected from each of ten bulls (3-8 years) by electro-ejaculation, diluted in three Tris-egg yolk extenders (Triladyl^® , 7% GLY-based and 7% EG-based) and evaluated for sperm motility, viability and morphology at three time periods (fresh - 0 hr, pre-freeze - 4 hr and post-thaw). Tuli bulls produced larger (11.8 ± 0.31 ml vs. 8.5 ± 0.38 ml) and more concentrated ejaculates of lower fresh semen quality. Breeds differed across time for motility and morphology, but not viability. Mashona bull semen had significantly higher motility and normal morphology values at each sampling time. Bulls classified as poor freezers had lower concentration (0.70 ± 0.09 × 10⁹  sperm/ml vs. 1.37 ± 0.10 × 10⁹  sperm/ml), sperm motility index (SMI, 35.0 ± 3.4 % vs. 67.8 ± 2.1 %) and viability (69.7 ± 1.1 % vs. 75.7 ± 1.0 %) compared to good freezers. Maintenance of semen quality by GLY and EG did not differ between breeds, poor and good freezers, or age groups. The interaction breed by extender across time did not reach statistical significance for all variables. The study revealed that bull and breed variation in sperm quality and cryosurvival is not modified by replacing GLY with EG, suggesting that cryostress tolerance of sperm may be under control of mechanisms other than differential response to GLY cytotoxicity.

Exogenous cholesterol modulates oxidative stress and freezability of mithun spermatozoa

Effect of cholesterol loaded cyclodextrin (CLC) on improvement of semen quality parameters (SQPs) and deduction of oxidative stresses following cryopreservation in mithun was explored. Total 50 ejaculates were selected out of 105 collected based on preliminary SQPs. Sperm was treated with 1 mg (Gr II) and 2 mg (Gr III) of CLC/ 120×106 spermatozoa and without CLC served as control (Gr I). Diluted semen samples were cryopreserved at ultralow temperature. Frozen thawed samples were evaluated for motility (progressive forward [FPM]; in bovine cervical mucus penetration test [BCMPT] and in computer assisted sperm analyzer [CASA]), viability, total sperm and nuclear abnormality, intactness of plasma membrane and acrosome, intracellular enzymatic leakage and oxidative profile (Malondialdehyde; MDA). Result revealed a significant improvement in motility (FPM, BCMPT and CASA), viability, acrosomal integrity, cholesterol content and reduction of sperm and nuclear abnormalities, leakage of intracellular enzymes and oxidative stressors in 1 mg CLC treated group as compared to control. Moreover, intactness of acrosome and biochemical membrane was protected significantly in extender containing 1 mg CLC. Hence inclusion of mithun spermatozoa with CLC (1 mg/120×106) prior to freezing improved the survivability in cryopreservation. The results clearly indicated the beneficial effects of CLC supplementation on freezability by reducing cryodamage and protecting the spermatozoa integrity.

Study on sperm motility and velocity parameters of freshly collected mithun semen through computer-assisted sperm analyser (CASA)

The objective of this study was to evaluate the quality of mithun semen by computer assisted sperm analysis (CASA). Ejaculates (50) were analysed by CASA. Semen motility was evaluated for kinetics parameters. The percentage of total motile and progressive motile spermatozoa were determined. Several velocities parameters were also determined viz., average path velocity (VAP, μm/s), track speed (VCL,μm/s), progressive velocity (VSL, μm/s), lateral amplitude (ALH), beat frequency (BCF, Hz), straightness (%), elongation (%), linearity (%), and area (μm sq). The result revealed a strong positive correlation between various CASA parameters (PMOTVAP, PMOT- VSL, VAP-VSL, VAP-ALH, VSL-ALH, STR-LIN).The present study confirmed the usefulness of CASA for a quick and objective analysis of sperm concentration, motility and other velocity parameters.

High resveratrol or quercetin concentrations reduce the oscillation index of frozen goat semen

ABSTRACT The aim of this study was to evaluate the effect of different concentrations of trans-resveratrol or quercetin on the ability of goat sperm to withstand being frozen. Six pools of semen obtained from six male goats were processed with different concentrations of resveratrol or quercetin (Experiment 1: 0, 15, 25, 50, 75 or 100µM resveratrol; Experiment 2: 0, 15, 25, 50, 75 or 100µM quercetin) and frozen. After thawing, the semen was evaluated for sperm kinematics, plasma membrane and acrosome integrity, morphology and oxidative stress following 0 and 1h of incubation. Immediately after thawing (0h), wobble (oscillation index) in the groups treated with 100µM of quercetin or resveratrol was lower (P<0.05) than in those treated with 0 and 25µM resveratrol and 0µM quercetin, respectively. After 1h of incubation, the total motility in treatments with 15, 50 and 75µM quercetin, as well as the plasma membrane integrity in all quercetin concentrations were lower (P<0.05) than at 0h. In opposition, the linearity of semen samples treated with 100µM quercetin and the straightness of those treated with 75 and 100µM quercetin were lower (P<0.05) at 0h than at 1h after thawing. Thus, it can be concluded that resveratrol and quercetin at high concentrations (100µM) transiently reduce the wobble of goat sperm submitted to frozen storage, and that quercetin (75 and 100µM) increases the linearity and straightness over time, which can be favorable for fertility.