Effects of different extenders and additives on liquid storage of Awassi ram semen

Abstract

The aim of this study was to evaluate the effects of different extenders and additives on ram semen during liquid storage and to demonstrate the role of oxidative stress parameters on this process. In the present study, ejaculates taken by artificial vagina twice a week from 4 rams during the breeding season were used. They were mixed and used if motility and viability were above 70% and there was a 95% intact acrosome. The semen specimens were diluted by Tris-citrate-glucose (TRIS), Tris-TES (TEST), HEPES-buffered Tyrode lactate (TL-HEPES), and Dulbecco's phosphate-buffered saline (PBS) extenders supplemented with different additives [centrifuged egg yolk, Equex-STM, bovine serum albumin (BSA), and ethylenediaminetetraacetic acid (EDTA)]. The specimens were stored at 4 degrees C for up to 96 h and evaluated for motility, membrane integrity, acrosome integrity, mitochondrial membrane potential (MMP), and oxidative stress parameters. At the end of the 96-h storage, the highest sperm motility was 64.2 +/- 3.7% (P < 0.05) and significant loss of sperm motility and membrane integrity were not detected in extender TEST-3, but the MMP rate significantly declined. Acrosome integrity was not affected by storage time or extender types. BSA and EDTA decreased lipid peroxidation (LPO) and total oxidant status (TOS), but did not positively affect motility or membrane integrity. As a result, TRIS, TEST, and TE-FIEPES-3 were observed to provide better protection for ram semen during liquid storage at 4 degrees C than other extenders. The role of oxidative stress and MMP are considerable in liquid storage.