Research articleEvaluation of quail and turkey egg yolk for cryopreservation of Nili-Ravi buffalo bull semen

Egg yolk is used as a cryoprotectant for semen in different mammalian species including buffalo. Egg yolk from different sources may affect freezability of buffalo bull semen. Quail egg yolk (QEY) and turkey egg yolk (TEY) in Tris-citric acid extender was evaluated for post-thaw quality and in vivo fertility rate of cryopreserved buffalo bull semen. Ejaculates were collected on weekly basis from six Nili-Ravi buffalo bulls (12 ejaculates/bull) for a period of 6 weeks and diluted at 37 °C with tris-citric egg yolk extender (50 × 106 motile spermatozoa mL−1) containing different levels of QEY or TEY (5%, 10%, 15%, and 20%) or 20% chicken egg yolk (CEY; controls) and cryopreserved. Percent post-thaw sperm motility (48.3 ± 3.8), plasma membrane integrity (67.9 ± 5.3), live/dead ratio (68.2 ± 5.0), and viability (50.5 ± 3.7) were recorded higher (P < 0.05) in extender containing 5% QEY compared with control. However, TEY at 10% in extender improved (P < 0.05) the post-thaw sperm motility (57.5 ± 5.2), plasma membrane integrity (53.5 ± 4.5), livability (75.3 ± 6.0), and viability (73.5 ± 6.5) compared with higher concentrations of TEY and controls (20% CEY). The chromatin damage (2.0 ± 0.9) and intracellular enzymes, glutamic oxaloacetic transaminase (24.8 ± 3.5) and lactic dehydrogenase (77.7 ± 4.5), release were lower (P < 0.05) in extender containing 10% TEY compared with the controls. In vivo fertility was compared after artificial insemination with semen from two buffalo bulls that was cryopreserved in extenders containing 5% QEY, 10% TEY, or 20% CEY. A total of 600 inseminations (200 inseminations per extender) were recorded; the overall fertility rate was significantly higher (P < 0.05) with semen cryopreserved in extender containing 5% QEY (57.5 vs. 42%) and 10% TEY (57.5 vs. 42%). compared with 20% chiken egg yolk. In conclusion, QEY at 5% and TEY at 10% offers advantages over 20% CEY in terms of in vitro post-thaw semen quality and in vivo fertility of buffalo.