Acrosome membrane integrity and cryocapacitation are related to cholesterol content of bull spermatozoa

To evaluate the cryoinjury prediction of spermatozoa in relation to its cholesterol content at fresh and frozen-thaw stages. Ejaculates (n=12) were processed for cryopreservation, acrosome integrity (fluorescent and giemsa stains), cryoinjury (distribution of non capacitated, capacitated and acrosome reacted, pattern F, B and AR, respectively of Chlortetracycline, CTC assay), in vitro fertiltiy (IVF) and cholesterol content of spermatozoa at fresh, pre-freeze and frozen-thaw stages were evaluated. Values were fitted in prediction equation to predict acrosome integrity (AI) and cryoinjury. Study indicated that cholesterol content of fresh spermatozoa can be used to predict cholesterol content of spermatozoa at pre-freeze and frozen-thaw stages of cryopreservation protocol with medium to high level of accuracy (P<0.05 and P<0.01, respectively). Cholesterol content of fresh spermatozoa can be used to predict AI, pattern B and AR and Penetration Index (PI) of IVF with medium level of accuracy (P<0.05) at frozen-thaw but not at pre-freeze stage. Similarly cholesterol content of frozen-thaw spermatozoa can be used to predict AI and pattern AR of frozen-thaw spermatozoa with medium level of accuracy (P<0.05). This study revealed strong evidence that cholesterol content of fresh as well as frozen-thaw bull spermatozoa can be a good predictor of level of cryoinjury following preservation at ultra low temperature.