Effect of L-cysteine on Post Thaw Quality of Nili Ravi Buffalo (bubalus Bubalis) Bull Spermatozoa Cryopreserved in Tris Citric Acid Extender

This study was designed to determine effect of various concentrations of Lcysteine on frozen-thaw semen quality of Nili Ravi buffalo. Single ejaculate of four buffalo bulls (Nili-Ravi) was collected at weekly intervals for 5 weeks. Ejaculates of acceptable motility (≥70%) were pooled and semen was diluted by tris citric acid extender (TCAE; 300 mosm/kg osmotic pressure and ~7.0 pH) having 4 levels of L-cysteine (0.0, 2.0, 5.0 and 8.0 mM). Semen was equilibrated at 4 ̊C and packaged in 0.5 mL French straws with 20×106 spermatozoa/ straw and then frozen in liquid nitrogen. L-cysteine inclusion levels had non-significant (P> 0.05) effect on spermatozoa motility, viability, NAR, PMI and on lipid peroxidation. However, DNA damage in spermatozoa was significantly higher (P<0.05) in 8.0 mM Lcysteine. It was concluded that L-cysteine (2.0 and 5.0 mM) addition to cryopreserved semen had no significant effect on post thaw semen characteristics, except at 8 mM which adversely affected DNA integrity. This may be due to its toxicity at this concentration.