Effect of Liquid Nitrogen Flushing of Extender on Seminal Antioxidant Profile of Murrah Buffalo during Cryopreservation.

BACKGROUND: The dissolved oxygen in the extender may act as a source for the production of reactive oxygen species that may lead to reduced seminal antioxidant profile which in turn may be responsible for impaired frozen thawed sperm quality and fertility. OBJECTIVE: To study the effect of adding liquid nitrogen into the extender on semen freezability and seminal antioxidant profile in buffalo. MATERIALS AND METHODS: Semen extender was prepared freshly and divided into two sub extenders namely, Extender I: control (non deoxygenated) and Extender II: partially deoxygenated by using LN2 flushing). The estimation of dissolved oxygen (DO) level was done in both extenders. Semen samples with mass motility of ≥ 3+ and individual progressive motility of 70% and above, collected from murrah buffalo bulls were utilized for the present study. Each semen sample was split into two group's viz., group I: diluted with extender I and group II: diluted with extender II up to 60×106 sperm/mL. The diluted semen samples were packed into French mini straws (0.25 mL), sealed with polyvinyl alcohol powder, kept for 3 h at 5°C for equilibration and then kept in automatic programmable freezer until temperature of straws reached -145°C followed by plunging into liquid nitrogen (-196°C). The evaluation of semen samples was carried out for various seminal attributes (sperm motility, live sperm count, acrosomal integrity, and hypo-osmotic swelling (HOS) response) and antioxidant profile (superoxide dismutase (SOD), glutathione peroxidase (GPx) and total antioxidant capacity (TAC)) at pre freeze and post thaw stage. RESULTS: Sperm motility, live sperm count, acrosomal integrity, HOS response were significantly (P<0.05) higher in group II as compared to group I. The average seminal SOD, GPx and TAC levels were significantly (P<0.05) higher in group II as compared to group I at pre freeze and post thaw stage. CONCLUSION: It is concluded that partial deoxygenation of the extender prior to its addition to semen enhances sperm quality in terms of sperm motility, live sperm count, acrosomal integrity, and hypo-osmotic swelling (HOS) response and also improves seminal antioxidant profile (superoxide dismutase (SOD), glutathione peroxidase (GPx) and total antioxidant capacity (TAC).

Reduction of dissolved oxygen in semen extender with nitrogen gassing reduces oxidative stress and improves post-thaw semen quality of bulls.

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 (N2) 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 N2 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.

Effect of pregnancy on some biochemical parameters in Sahel goats in semi-arid zones.

The effects of pregnancy on some biochemical parameters were studied using 20 sexually mature, cycling goats with weight range 20-25 kg. They were randomly separated into two groups of 10 animals each. In one group, oestrus was detected while going round with a buck in the morning and evening; a single buck on detection of oestrus mated the does and the does were tagged as pregnant after confirmation of non-return of oestrus. The other group was kept cycling and tagged as non-pregnant. The mean serum glucose concentration in pregnant does was 63.35 +/- 7.70 mg/dl, significantly lower than 71.59 +/- 1.14 mg/dl for non-pregnant does (p < 0.05); the mean serum cholesterol concentrations were 79.48 +/- 14.93 for pregnant and 67.29 +/- 1.10 for non-pregnant does, with significant difference (p < 0.05). Protein (g/dl), urea (mg/dl), creatinine (mg/dl) and free fatty acid (microequiv/L) remained unchanged between the two groups (p > 0.05), as did the liver enzymes (ALT, AST). Therefore this study showed that low serum glucose and high cholesterol levels are features of mid to late pregnancy in Sahel goats.