<div>Background: Artificial insemination with frozen semen is of great value for livestock breeding and improvement. However, the procedure of cryopreservation leads to varying degree of oxidative and cryodamage to sperms deteriorating its quality, capacitation status and fertility. Hence, a variety of protocols, cryoprotectants and additives have been tried to protect sperms from such damages. This study was aimed to evaluate the antioxidant and cryocapacitation inhibitory potential of Mifepristone, Sericin and Taurine in routine extender on cryopreserved bull semen including in vivo fertility. 
 
Methods: Semen ejaculates of 3 Gir and 3 Murrah bulls with &gt;75% initial motility were split-diluted @ 100 million spermatozoa ml-1 using TFYG extender without and with Mifepristone (10 &micro;g/ml), Sericin (5 mg/ml) and Taurine (4 mg/ml) and frozen in LN2 using a programmable biofreezer. The freshly diluted as well as frozen-thawed samples were assessed for sperm motility, viability, plasma membrane integrity, CTC (chlortetracycline) fluorescence assay and seminal plasma oxidative markers. The straws frozen as above were used to inseminate 100-375 cows and/or buffaloes with each treatment involving well trained field AI technicians. Conception rates were determined based on confirmation of pregnancy per-rectum 45-60 days after first AI in non-return cases. 
 
Result: The mean percentages, on dilution and at post-thaw stage in particular, of motile, live, HOS reactive and non-capacitated sperm were significantly (p&lt;0.01) higher with reduced lipid peroxidation (MDA, SOD and GPx) whereas capacitated and acrosome reacted sperm were lower in Mifepristone supplemented extender than in control extender and the values for Sericin and Taurine fortified extender were intermediary in both the species. The first AI conception rates obtained for Gir and Murrah bull semen cryopreserved in control extender and extender supplemented with Mifepristone, Sericin and Taurine were 44.48, 51.11, 47.22 and 48.72% in cattle and 44.44, 55.40, 51.57 and 52.05% in buffaloes, respectively, suggesting that all additives used and Mefipristone in particular can be advantageously incorporated in the semen extender for cryopreservation of both cattle and buffalo semen.</div>

Evaluation of Cryoprotective, Cryocapacitation Inhibitory and Fertility Enhancing Potential of RU-486, Sericin and Taurine in Cattle and Buffalo Semen

<div>Background: The evaluation of bull fertility essentially involves semen analysis and conception rates among inseminated females. The conventional evaluation is relatively imprecise, time consuming and subjected to individual variations, while computer assisted sperm analysis (CASA) is a quite faster, precise and objective tool to identify differences in sperm motility and velocity/kinematics attributes and avoids subjective errors. The present study was planned to evaluate and compare the CASA traits of fresh and frozen-thawed semen of Gir and Murrah bulls in Tris extender without and with different antioxidant additives by adopting Biovis CASA. 
 
Methods: The semen ejaculates with &gt;75% initial motility from 3 Gir and 3 Murrah bulls were split-diluted at 100 million sperm per ml using Tris-citrate-fructose-yolk-glycerol (TFYG) extender without (control) and with three antioxidant additives, viz., Mifepriston (10 &micro;g/ml), Sericin (5 mg/ml) and Taurine (4 mg/ml), were filled in French mini straws and frozen in liquid nitrogen vapour using a programmable biofreezer. The freshly diluted and frozen-thawed semen samples were assessed for sperm motion characteristics, velocity/kinematics using Biovis CASA.&nbsp; 
 
Result: The mean percentages of total motile spermatozoa, irrespective of additives, in freshly diluted and frozen-thawed semen were 85.50&plusmn;0.92 and 48.76&plusmn;1.69 for Gir bulls and 85.03&plusmn;0.72 and 52.61&plusmn;1.46 for Murrah bulls, respectively. The mean total motile as well as rapid and slow progressive motile sperm percentage were significantly enhanced by fortification of TFYG extender with Mifepristone than in control extender, while values for Sericin and Taurine were intermediary and statistically similar to Mifepristone. The per cent decline in total motile sperm due to freezing-thawing was more or less same in both the breeds for all the extender additives, being lowest in Mifepristone supplemented extender in cattle (32.27 vs 48.81%) and buffalo (31.27 vs 43.14%) semen. The rapid and slow progressive motile sperm also followed the same pattern. The values of VAP and VCL were significantly (p&lt;0.05) higher and VSL lower in Murrah than Gir breed at post-thaw stage. The overall mean linearity (%), straightness (%), beat-cross frequency (hz), lateral head displacement (&micro;m), wobbling index (%), dancing velocity (&micro;m2/s) and dancing mean (&micro;m2/s) of sperm were higher in Murrahs than in Gir semen with significant (p&lt;0.01) difference at post-thaw stage. The fortification of extender with Mifepristone improved all these traits at post-thaw stage compared to other additives and control TFYG extender. The per cent decline in these traits due to freezing stress was much lower in buffalo sperm than the cattle sperm particularly with Mifepristone fortification. It was concluded that freezing-thawing stress adversely affected the motion and kinematics of both cattle and buffalo sperm and that Tris extender fortified with antioxidant additives, particularly Mifepristone @ 10 &micro;g/ml, protected sperm from adverse effect of dilution and cryopreservation with improved post-thaw sperm quality.</div>

<div>Fortification of Tris Extender with Mifepristone, Sericin and Taurine Improves Velocity and Kinematics of Fresh and Frozen-thawed Bovine Spermatozoa&nbsp;</div>