| Abstrakt: |
The milk added to the semen extender media acts by binding to seminal plasma proteins, which may protect the sperm cell from undergoing the capacitation process or acrosomal reaction in advance. Among these proteins, sodium caseinate stands out, which represents 80% of all proteins present in milk. Caseins are also able to protect the sperm cell by decreasing the loss of lipids through the plasma membrane, decreasing the binding of seminal plasma proteins to the plasma membrane. The objective of this study was to determine whether the addition of sodium caseinate in different concentrations to the freezing extender medium favors sperm viability after a long period of refrigeration. For this, three concentrations of sodium caseinate were used, 0.0, 1.0, and 2.0%, in the cryopreservation medium. In addition to caseinate concentrations, three refrigeration times were tested at 5 ºC, 12 and 24 hours. So, the ejaculates were divided into nine groups 0H/0%, 0H/1%, 0H/2%, 12H/0%, 12H/1%, 12H/2%, 24H/0%, 24H/1% and 24H/2%. Ten stallions underwent reproductive evaluation, being included only those with sperm motility ≥ 70%. Fluorescent probes, hypoosmotic (HOST), and thermoresistance (TTR) tests were used to evaluate the functionality of the plasma membrane and the longevity of sperm cells, respectively. There was no stat. difference (p>0.05) between groups for membrane integrity. However, for the TTR, it was possible to observe a stat. difference (p<0.05) for the 24H/2% group with a lower response. The integrity of the plasma membrane, compared to the refrigeration time and the concentration of sodium caseinate, did not change. Therefore, it was concluded that sperm longevity was impaired with the use of a 2% concentration of sodium caseinate, and its use is not recommended for sending refrigerated semen, for insemination or freezing, that exceeds 12 hours. [ABSTRACT FROM AUTHOR] |
