EFFECT OF EXTENDER OSMOLALITY AND BUTYLATED HYDROXY TOLUENE SUPPLEMENTATION ON POST THAW QUALITY AND FERTILITY OF NILI RAVI BUFFALO BULL (BUBALUS BUBALIS) SEMEN
F. Wadood*, M. Aleem, A. Ijaz1, N. Ahmad, M. S. Yousaf1and D. H. Mughal1
Department of Theriogenology, 1Department of Physiology, University of Veterinary and Animal Sciences, Lahore, Pakistan-38040
*Corresponding Author: firstname.lastname@example.org
Aim of the present study was to develop semen extender for cryopreservation of buffalo bull semen to improve the post thaw quality and conception rate. Study consisted of three experiments, single ejaculate of four Nili Ravi buffalo bulls were collected for a period of 5 weeks for each of experiment I and II. In experiment-I, osmotic pressure of tris citric acid extender (TCAE) was optimized. Semen of four bulls was pooled and calculated quantity was added to five solutions of variable osmotic pressures of TCAE (260, 270, 280, 290 and 300 mOsm/kg). In experiment-II, TCAE with best osmotic pressure as recorded in experiment-I was supplemented with butylated hydroxyl toluene (1.75, 2.0, 2.25, 0.0 mM and DMSO). As butylated hydroxyl toluene (BHT) was dissolved in dimethyl sulph oxide (DMSO), DMSO control was also run to rule out its reported effect as antioxidant. Post thaw spermatozoa motility, viability, plasma membrane integrity (PMI), normal apical ridge (NAR),DNA damage rate and lipid peroxidation were assessed in first two experiments. In experiment-III, pregnancy rate comparison between Trial and Control extenders was done. In experiment-I, at 300 and 280 mOsm/kg spermatozoa motility was significantly higher (P<0.05) compared to 260 mOsm/kg, and NAR at 300 mOsm/kg was significantly higher than other osmotic pressures. In experiment-II, a higher spermatozoa motility was recorded at 2.0mM BHT than other groups except 0.0mM BHT. At 2.25mM BHT, spermatozoa viability and PMI rates were lower compared to 1.75 and 2.0mM, respectively. Moreover, higher DNA damage was observed at 2.25mM as compared to 0.0, 2.0mM BHT and DMSO. A lower lipid peroxidation in BHT treated groups was also noted. Pregnancy rate was 24 and 42% in Comparative and Trial extenders, respectively but difference was not significant. In conclusion, TCAE (300 mOsm/kg) with BHT (2.0 mM) improved post-thaw semen quality of Nili-Ravi buffalo bulls.
Keywords: Buffalo, Spermatozoa, Cryopreservation, Extender, Osmolality, antioxidant.