Importance of the work: Cryopreservation of indigenous black rabbit sperm poses
challenges due to induced damage that affects viability, motility and membrane integrity.
Objectives: To evaluate the impact of varying concentrations of cysteine and egg yolk on
the cryopreservation medium.
Materials & Methods: In Experiment 1, egg yolks were used at concentrations of
0%, 5%, 10% or 15%. In Experiment 2, cysteine was used at concentrations of 0 mM,
1.25 mM, 2.5 mM or 5 mM. Samples were preserved in liquid nitrogen for 72 hours,
before being thawed and evaluated.
Results: Based on the results in Experiment 1, 15% egg yolk was the optimal
concentration for preserving rabbit sperm, with values for overall mobility, progressive
motility, viability rate and membrane integrity of 52.31%, 38.74%, 59.32% and 44.79%,
respectively. These differences were significant (p < 0.05) compared to the other
concentrations. In Experiment 2, the tris citrate glucose (TCG) medium supplemented
with 15% egg yolk and combined with 2.5 mM cysteine produced the best results and was
significantly (p < 0.05) different from the other concentrations, with overall values for
mobility, progressive motility, viability rate and membrane integrity of 63.85%, 45.26%,
74.50% and 51.56%, respectively.
Main finding: Using a TCG storage solution enhanced with 15% egg yolk and 2.5 mM
cysteine improved rabbit sperm quality during cryopreservation, demonstrating the
positive effects of egg yolk and cysteine in sperm cryopreservation.