Evaluation of equilibration time on boar semen cryopreservation protocols: a physiological and morphofunctional study

Abstract

The use of cryopreserved semen in modern swine production accounts for only 1% of all artificial inseminations performed worldwide, hence, its applicability is still very restricted, demanding more studies aiming at improving this biotechnology, which would lead to its full implementation into the commercial level. On this path, several techniques have been developed and applied in recent decades in order to improve the freezability of semen, such as changing cryopreservation protocols, the use of specific fractions of the ejaculate, holding time as well as the application of equilibration time. Thus, the aim of the present project is to evaluate the application of the equilibration time in boar semen cryopreservation protocols and deepen the understanding of this action in relation to the physiology and morphofunctionality of swine spermatozoa. For this purpose, six boars of a commercial hybrid line will be used. Six ejaculates of each animal will be collected by the gloved-hand technique. After collection, semen samples will be analyzed for motility characteristics by the computerized system for semen analysis, concentration and sperm morphology. Semen samples will be subjects to a 24 hour period of holding time. After the holding time period, samples will be destined to the cryopreservation procedure, remaining under equilibration time (5 ° C) for periods of 0, 2 and 4 hours. After cryopreservation, 4 straws will be thawed at 37 ° C for 30 seconds for analyzes of sperm physiology and morphofunctionality, such as kinematics (CASA), integrity of plasma and acrosomal membranes, mitochondrial membrane potential, lipid peroxidation, membrane fluidity, intracytoplasmic oxidative stress as well as translocation of phosphatidylserine. For the statistical analysis, the SAS software (2012) will be used and the data will be analyzed for variance and normality of the residues. Data that does not meet the assumptions will be processed and submitted to the PROC MIXED. The averages will be analyzed by the Tukey test and the ideal time of equilibrium will be obtained through polynomial regression equation. (AU)