Comparação entre os sistemas automatizado e convencional de criopreservação de sêmen bovino

The objective of this study was to compare the efficiency of bovine semen cryopreservation using the controlled-rate freezing machine versus the conventional method (uncontrolled curve) by the parameters of sperm quality and viability in post-thaw period. Semen from four adult crossbreed bulls was cryopreserved in Tris-yolk-glycerol medium. The computer assisted analysis of thawed semen detected the following results: PM 56.50±22.25%; VAP 34.77±4.25?m/s; VSL 28.17±4.25?m/s; VCL 58.45±6.85?m/s; STR 82.00±2.31%; LIN 49.50±3.32%, to automated system and PM 57.00±13.11%; VAP 25.75±1.66?m/s; VSL 23.32±1.99?m/s; VCL 63.32±1.79?m/s; STR 82.25±3.59?m/s; LIN 50.00±4.97?m/s to conventional cryopreservation system. The results of plasma membrane and acrosome integrity evaluation were 54.7±12.55% and 36.13±22.20% for the automated system and 53.22±13.22% and 47.26±5.74% for the conventional system, respectively. The parameters evaluated demonstrated that there was no statistical difference between the cryopreservation systems. Thus, the choice of the bovine semen cryopreservation method to be used on a farm is a responsibility of the technician, and should be based on the reality of each farm. Therefore, it is always necessary to consider that the conventional system of bovine semen cryopreservation can vary more than the automated system, which, despite the cost of the equipment, can ensure repeatability of the results and consequent quality of cryopreserved bovine semen. KEYWORDS: artificial insemination; biotechnology; bovine sperm; cryopreservation; cryopreservation curve .