Cryoinjury in relation to cholesterol content of bull spermatozoa

Though semen cryopreservation has many advantages, it decreases tolerance of spermatozoa to stress of temperature variations, thus disposing spermatozoa to increased cryoinjury. Predicting cryoinjury to spermatozoa is difficult with available laboratory protocols. The present study was designed to evaluate the cryoinjury prediction of sperm in relation to its cholesterol content. The cholesterol content at fresh, pre-freeze and post-thaw stage was 21.95±0.97, 9.58±0.45 and 7.44±0.44 ìg/100 million spermatozoa. Semen quality parameters (SQP) at pre-freeze and post-thaw stages were individual motility (71.58±1.29 vs. 47.83±1.16), acrosome integrity (71.00±1.48 vs. 61.58±1.70), Chlortetracycline (CTC) pattern (F: 29.67±1.14 vs. 15.83±1.02; B: 48.83±2.06 vs. 53.58±1.27; AR: 21.50±1.84 vs. 30.58±1.85). Study indicated that cholesterol content of fresh spermatozoa could be used to predict cholesterol content of spermatozoa at pre-freeze and post-thaw stages with medium to high level of accuracy. This study revealed strong evidence that cholesterol content of pre-freeze bull spermatozoa could be a good predictor of level of cryoinjury following preservation at ultra low temperature.