Influence of systems and freezing curve in equine semen freezability and fertility

ABSTRACT The effect of freezing curves on sperm parameters and fertility, using resistant and sensitive semen to cryopreservation, was evaluated. In experiment 1, Semen from 4 stallions resistant to freezing was used: Group 1, straws were cooled to 5°C and frozen with a curve of - 8°C/min; Groups 2 and 3, straws were cooled to 5°C (0.5°C/min) and frozen with curves of - 20°C / min and - 10°C/min, respectively. In experiments 2 and 3, 5 stallions (Mangalarga Marchador) presenting respectively resistant and sensitive sperm to cryopreservation were used: Group 4, same methodology described for Group 1 was performed; Groups 5 and 6, straws were cooled to 5°C (0.5°C/min) and frozen with a curve of - 20°C/min. between 5°C and - 60°C and -10°C/min. between - 60°C and - 100°C (Group 5) and - 25°C/min. 5°C to - 100°C (Group 6). Thawed-semen was evaluated by the computerized method CASA. In Experiment 1, there was no difference in the evaluated parameters. In Experiment 2, total motility (MT) and progressive motility (PM) were higher in Group 6 compared to Group 4. In Experiment 3, TM was higher in Group 6 than Group 4. The faster freezing curves showed better parameters of sperm kinetics after thawing, for the Mangalarga Marchador stallion semen.