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Fertility associated antigen (FAA) are more abundant in semen of bulls with high fertility. The objective was to investigate relationship of FAA, either membrane bound and/or in seminal plasma, with that of markers of oxidative stress, mitochondrial activity and acrosome integrity of live cells, in cryopreserved spermatozoa. Grouping of bulls was done by electrophoretic profiling of proteins from seminal plasma (SP), and sperm membrane (SM), based on presence/absence of the FAA in SP and/or SM or both. Group I had detectable FAA in both SP and SM; Group II, FAA detected only in SM; Group III, detectable FAA only in SP and Group IV, undetectable FAA in both SP and SM. At post-thaw stage, the lipid peroxide levels were significantly lower (p<0.05) and the activity of primary free radical scavengers (superoxide dismutase and catalase) was significantly higher (p<0.05) in Groups I and II. Correspondingly, Group I and II showed significantly higher (p < 0.05) per cent of acrosome intact live spermatozoa and sperm cells with functionally active mitochondria. Collectively, this study showed that the presence of FAA on the sperm membrane is related to greater protection against oxidative stress ensuing improved acrosome intact live-sperm cells with functional mitochondria. [ABSTRACT FROM AUTHOR]

Background: Oxidative stress occurs when oxygen or oxygen derived oxidants exceed antioxidants and become responsible for poor post-thaw semen quality during the cryopreservation process. Therefore, the present study was designed to investigate the effects of dissolved oxygen (DO) levels (4, 6 and 8 ppm) in semen extender on freezability of crossbred bull spermatozoa. As the gap between 4 and 8 ppm existed in earlier studies, DO of 6 ppm in semen extender was further standardized and the effects were compared with other respective groups to contemplate any improvement in post-thaw semen quality. Methods: For the experiment, Tris-egg Yolk-Glycerol (TYG) extender was partially deoxygenated by nitrogen gassing @ 2-3 bubbles/ sec at 34°C for 0, 16, 12 and 9 minutes to obtain DO levels of 11.7 ppm (Group-I/control), 4 ppm (Group-II), 6 ppm (Group-III) and 8 ppm (Group IV), respectively and collected semen samples were diluted with these extender groups to have 80x106 spermatozoa/ ml of the extender. Semen samples were evaluated for individual progressive motility (IPM), lipid peroxidation (LPO), total antioxidant capacity (TAC), plasma membrane integrity, acrosomal integrity and apoptotic changes at different stages of cryopreservation. Result: At the post-thaw stage, progressive motility was greater (p<0.05) in Group II compared to Group I and the least reduction from the post-dilution to the post-thaw stage was observed in Group II. In comparison to Group I, Groups II, III and IV showed lesser (p<0.05) MDA production with Group II having greater (p<0.05) TAC concentration than other groups at the post-thaw stage. A declining trend was observed in membrane integrity as DO levels increased from 4 ppm to 11.7 ppm. Acrosomal integrity did not differ among treatment groups, but, found to be higher (p<0.05) than the control group. Per cent viable spermatozoa was greater (p<0.05) in Group II than Group I and vice versa for necrotic spermatozoa as assessed by Annexin VFITC/PI staining. In conclusion, reducing the DO level to 4 ppm before cryopreservation improved the freezability by reducing oxidative stress and apoptotic changes while, above 4 ppm tended to lower it. An appreciable improvement in freezability can be seen at 6 ppm of DO, but, not up to that extent as observed at 4 ppm. [ABSTRACT FROM AUTHOR]

The present study was designed to evaluate the effect of factors like hormones, antisperm antibody (ASA), and oxidative stress and its relation with semen quality in crossbred bulls. Ejaculates from two bulls were categorized into good (n = 12) and poor (n = 12) based on initial progressive motility, that is, ≥70% and ≤50%, respectively. The level of hormones like Testosterone (p < 0.05) and PGE2 (p < 0.01) was significantly higher in good-quality ejaculates compared to poor-quality ejaculates; however, estradiol (p < 0.05), progesterone, oxidative stress, and ASAs were significantly higher (p < 0.01) in poor-quality ejaculates compared to good-quality ejaculates. Therefore, it could be concluded that oxidative stress and hormonal imbalance might have resulted in high number of dead and defective spermatozoa which was ultimately responsible for poor quality semen ejaculates. [ABSTRACT FROM AUTHOR]

The current study intended to optimize the concentration of Oxyrase in the semen dilutor and to evaluate its effect on freezability of spermatozoa of Sahiwal bulls. Supplementation of Oxyrase at 0.125 IU/mL concentration significantly reduced dissolved oxygen (DO) in the dilutor to 4 ppm in 16–18 min at 35 °C. For supplementation studies, a total of 24 ejaculates were categorized into poor and good ejaculates categories (n = 12 each) based on their initial progressive motility. Each ejaculate was further divided into two aliquotes. The first aliquote was diluted with tris-egg yolk extender without Oxyrase (control group) whereas, in the treatment group, Oxyrase was supplemented at the concentration of 0.125 IU/mL of extender. The parameters evaluated include cholesterol and plasma membrane phospholipids (PMP) at fresh, while IPM, acrosomal and plasma membrane integrity, cholesterol, PMP and oxidative stress parameters like lipid peroxidation (LPO), total antioxidant capacity (TAC) and reactive oxygen species (ROS) were evaluated at pre-freeze and post-thaw stages. The IPM and acrosomal intactness were higher (p < 0.05) in treatment group at post-thaw stage in good ejaculates. Oxyrase supplementation resulted in lower (p < 0.05) cholesterol leakage in both categories and lower (p < 0.05) LPO in good ejaculates at post-thaw stage. No statistical difference in ROS was observed between control and treatment groups at all stages whereas, level of TAC was higher (p < 0.05) in the treatment group compared to control group at post-thaw stage of both categories. Therefore, Oxyrase as an oxygen scavenging agent could preserve the post-thaw quality of Sahiwal bull spermatozoa. [ABSTRACT FROM AUTHOR]

Mithun ( Bos frontalis ) is a unique domestic free range bovine species of North Eastern hilly regions of India. The present study was designed to assess the seasonal effect of slow release exogenous melatonin (MT) implant on semen quality parameters (SQP) and in vitro zona binding ability (IVZ) of spermatozoa. The experimental animals were divided into Gr I: Control (n = 5) and Gr II: Treatment (n = 5; melatonin implant @ 18mg/50 kg bwt). A total of 20 semen samples/group in winter, spring, autumn and summer seasons (n = 160), twice per week were collected. Following cryopreservation, samples were evaluated for motility parameters (forward progressive, mobility & velocity by computer assisted sperm analyser (CASA), viability, acrosome integrity, plasma membrane and nuclear abnormality, functional status of mitochondria, enzymatic, antioxidant and oxidative profiles, and IVZ. The study revealed significant (p < 0.05) improvement in total motility, viability, acrosome-, plasma membrane-, and nuclear-integrity, and antioxidant profiles; with highest values in spring and lowest in summer season in the fresh semen in Gr II than the Control. A significant (p < 0.05) improvement in motility parameters, membrane potential of mitochondria, antioxidant profiles and reduction in sperm and nuclear abnormalities, leakage of intracellular enzymes and oxidative stress and IVZ index & binding percentage in post-thaw semen samples in melatonin supplemented than in un-supplemented control group was observed. It can be concluded from the study that slow-release melatonin supplementation can be effectively utilized to improve the antioxidant profiles and reduction of oxidative stress, with cascading beneficial effects on semen quality parameters and fertility status of the mithun bull. [ABSTRACT FROM AUTHOR]

Highlights • Dissolved oxygen (DO) in semen extender was reduced through a N 2 gassing process. • Reduction of DO reduced oxidative stress and DNA damage of spermatozoa. • It increased antioxidant potential, membrane integrity and MMP at post-thaw stage. • Maintaining DO at 4 ppm in semen extender yield optimal post-thaw semen quality. Abstract The objective of the present study was to investigate the effects of two different concentrations of dissolved oxygen (DO, 4 and 8) ppm in the extender on oxidative stress affecting plasma membrane integrity (PMI), mitochondrial membrane potential (MMP), and deoxyribonucleic acid (DNA) damage of bull spermatozoa following cryopreservation. For the experiment, nitrogen (N 2) gassing of the extender for varied time intervals yielded extender with DO concentration of 4 ppm and 8 ppm (Groups II and III, respectively). For the Control (Group I) without N 2 gassing, a DO concentration of 11.7 ppm was recorded. Following sample selection, ejaculates were divided into three aliquots and were extended to have 80 × 106 spermatozoa/mL of extender in the three groups. Semen samples were evaluated for reactive oxygen species (ROS), lipid peroxidation (LPO), total antioxidant capacity (TAC) and superoxide dismutase (SOD) at the fresh, pre-freeze, and post-thaw stages. Evaluation of PMI, MMP, and DNA damage were conducted on frozen-thawed samples. There were greater (P < 0.05) increase in ROS and LPO and decrease in TAC concentrations in Group I than Groups II and III. Mean values of SOD at the post-thaw stage was greater (P < 0.05) in Group II than Group I. There was a similar trend in the PMI in Groups II and III; MMP and DNA integrity in Group II was greater compared with Group I. In conclusion, results indicate there was a beneficial effect of maintaining DO concentrations at 4 rather than of 8 or 11.7 ppm in extender for sustaining post-thaw semen quality. [ABSTRACT FROM AUTHOR]

Contents Artificial breeding of mithun poses several challenges including lack of standard protocol for cryopreservation of spermatozoa. This is further complicated by harmful effects of hen's egg yolk ( EY) as additive in extender. Purified low-density lipoproteins ( LDL) extracted from EY have been shown as beneficial over EY extender for long-term semen storage in several species. This investigation explored use of LDL versus EY on semen quality and oxidative stress following freezing-thawing of spermatozoa. A total of 25 of 50 ejaculates based on biophysical parameters were selected for the experiment. After diluting with the Tris-citrate-glycerol ( TCG) extender, each sample was split into three equal aliquots: Group I, control, EY; Group II and Group III contained 8% and 10% purified LDL, respectively. Frozen-thawed samples were evaluated for motility parameters (progressive, and in the bovine cervical mucus penetration test [ BCMPT]), viability, sperm and nuclear abnormality, acrosome integrity, and enzymatic (leakage of intracellular contents) and biochemical (oxidative stress) profiles and in vitro fertility ( IVF) assay. Study revealed a significant ( p < .05) improvement in viability, sperm and nuclear abnormality, acrosome integrity, motility (progressive and in cervical mucus), cholesterol content, and reduction in the leakage of intracellular enzymes in Group II. Moreover, intactness of acrosome and biochemical membranes was protected significantly ( p < .05) in addition to significant ( p < .05) improvement in binding per cent and binding index in IVF assay in extender containing 8% LDL. These results demonstrate that although cryopreservation of mithun's spermatozoa in EY was comparable with other species, addition of 8% LDL holds a clear advantage over EY or 10% LDL. [ABSTRACT FROM AUTHOR]

High ambient temperature during summer in tropical and subtropical countries predisposes water buffaloes ( Bubalus bubalis ) to develop oxidative stress having antigonadotropic and antisteroidogenic actions. Melatonin is a regulator of seasonal reproduction in photoperiodic species and highly effective antioxidant and free radical scavenger. Therefore, a study was designed to evaluate the effect of sustained-release melatonin on biomarkers of oxidative stress i.e., the serum malondialdehyde (MDA) and nitric oxide (NO), and the total antioxidant capacity (TAC). For the study, postpartum buffaloes diagnosed as summer anestrus (absence of overt signs of estrus, concurrent rectal examination, and RIA for serum progesterone) were grouped as treated (single subcutaneous injection of melatonin at 18 mg/50 kg body weight dissolved in sterilized corn oil as vehicle, n = 20) and untreated (subcutaneous sterilized corn oil, n = 8). Blood sampling for estimation of serum TAC and MDA (mmol/L) and NO (μmol/L) was carried out at 4 days of interval from 8 days before treatment till 28 days after treatment or for the ensuing entire cycle length. Results showed serum TAC concentration was higher in the treatment group with a significant (P < 0.05) increasing trend, whereas MDA and NO revealed a significant (P < 0.05) decline. Serum MDA and NO were higher in control compared with those of treatment group. Moreover, buffaloes in the treatment group showed 90% estrus induction with 18.06 ± 1.57 days mean interval from treatment to the onset of estrus. These results report that melatonin has a protective effect by elevating antioxidant status and reducing oxidative stress resulting in the induction of cyclicity in summer-stressed anestrous buffaloes. [ABSTRACT FROM AUTHOR]