Effect of L-carnitine in a skimmed milk based-diluent on membranes preservation and kinetic activity of ram sperm under chilled conditions

The synergic effect of L-carnitine (LC) and skimmed milk base-extender (UHT) on the kinetic parameters and membranes integrity of cold-stored ram sperm was evaluated. For this purpose, twelve pools of thirty-six semen ejaculates that were collected with artificial vagina from twelve Merino rams were used. After initial evaluation, the semen was divided into 6 aliquots enough to diluted with UHT-extender (control) and 1mM (UHT-LC1), 2.5mM (UHT-LC2.5), 5mM (UHT-LC5), 7,5mM (UHT-LC7.5) and 10mM (UHT-LC10) of LC, respectively, at 200 x 106 cells/ml concentration. Semen samples were cold-stored (5ºC) up to 96 h. Kinetic variables and membranes integrity were assessed by CASA system (SCA) and triple fluorescence association test (IP/PNA-FITC/Mitotracker green). An ANOVA-one way and Bonferroni´s test were used to evaluated effects of LC doses. Overall, the total motility (TM, %), straight line velocity (VSL, μm/s) and total sperm with plasma and acrosome membranes integrity and high mitochondrial function (IPIAHM, %) were greater with all doses of LC (1 to 10 mM) than control group. Also, the UHT-LC5 group provided better values than others LC groups according to motilities. In conclusion, LC improves kinetic vigor and provides an antioxidant protective effect to sperm membranes of cold-stored ram when added to skimmed milk based-diluent