Programmable fast-freezing method improves the post-thaw motion dynamics, integrities of plasmalemma, mitochondrial transmembrane, DNA and, acrosome, and in vivo fertility of water buffalo (Bubalus bubalis) spermatozoa.

The effects of freezing methods (FR1, nonprogrammable/static, 5 cm above liquid nitrogen [LN2 ] for 10 min, plunging in LN2 ; FR2, programmable medium, +4°C to -15°C at 3°C min-1 , from -15 to -80°C at 10°C min-1 and final holding for 1 min at -80°C, plunging in LN2 ; FR3, programmable fast, from initial holding at +4°C for 2 min, from +4°C to -20°C at 10°C min-1 , from -20°C to -100°C at 30°C min-1 , final holding for 1 min at -100°C and plunging in LN2 ) were assessed on post-thaw in vitro quality and in vivo fertility of water buffalo spermatozoa. Mean sperm progressive motility (%), rapid velocity (%), average path velocity (μm s-1 ), straight line velocity (μm s-1 ), curved line velocity (μm s-1 ), integrities (%) of plasmalemma, mitochondrial transmembrane, DNA and acrosome were higher (p < .05) in samples cryopreserved with FR3 compared to FR1 and FR2. Similarly, in vivo fertility (%) of buffalo spermatozoa was higher (p < .05) with FR3 than FR1 (%; 68.0 versus 50.0). We concluded that programmable fast-freezing method (FR3) improves the post-thaw in vitro quality and in vivo fertility of water buffalo spermatozoa.