Effect of different concentrations of l-carnitine in extender for semen cryopreservation in sheep.

This study assessed the effect of l-carnitine (LC) in sheep semen extenders containing or not egg yolk for cryopreservation in sheep. Two extenders (TRIS-egg yolk or the commercial optiXcell™ IMV medium) were used, totaling six groups: IMV - (0, 5 and 10 mM LC) and TRIS - (0, 5 and 10 mM LC). After the freezing-thawing process and throughout incubation at 38 °C for up to 3 h, several parameters were evaluated: sperm kinetics, hypoosmotic, plasma membrane integrity, capacitation status and lipid peroxidation level. The supplementation of either 5 or 10 mM LC randomly affected some parameters and, overall, TRIS was superior (P < 0.05) than IMV extender. In the LC-groups, IMV had greater (P < 0.05) oxidative stress than TRIS. In conclusion, although LC affected isolated parameters, its supplementation in semen extender had no consistently beneficial effect on freezing-thawing ram sperm.