Efficiency of antifreeze glycoproteins for cryopreservation of Nili-Ravi (Bubalus bubalis) buffalo bull sperm

Experiments were conducted to evaluate the effect of Antarctic fish antifreeze glycoproteins, (AFGP) size 1-5 (34-10.5 kDa) and 7-8 (3.2 and 2.4 kDa) in extender on buffalo bull sperm at cooling (4 degrees C) and at post thawing. Semen was collected from three Nili-Ravi buffalo bulls with artificial vagina for 3 weeks. Qualifying ejaculates from each buffalo bull were diluted (at 37 degrees C having 50 x 10(6) sperm/mL) in tris-citric acid extender containing AFGP at 0 (control), 0.1, 1 and 10 mu g/mL. An aliquot of diluted semen was evaluated for sperm progressive motility and plasma membrane integrity, while the remaining fraction was cooled to 4 degrees C in 2 h. Further, an aliquot of cooled semen was evaluated for the previously described variables and the remaining fraction was cryopreserved (-196 degrees C). After 24 h of storage, straws were thawed at 37 degrees C for 30 s to assess post-thaw sperm quality. Inclusion of AFGP in the extender did not affect (P>0.05) sperm progressive motility and plasma membrane integrity of buffalo bull sperm at cooling stage (4 degrees C). However, at post thawing, improvement (P<0.05) in sperm progressive motility and plasma membrane integrity was recorded in extender containingAFGP 1-5 and AFGP 7-8 at 1 mu g/mL compared to the control. Percentage of live sperm with an intact acrosome remained similar (P>0.05) in extenders containing different amounts of AFGP and control. In conclusion, supplementation of 1 mu g/ml of AFGP in extender improved the motility and plasma membrane integrity of Nili-Ravi buffalo sperm after thawing. (C) 2015 Elsevier B.V. All rights reserved.