Efecto de la suplementación de L-carnitina a diluyentes a base de leche desnatada sobre la criosupervivencia de esperma equino

Abstract

L-carnitine(LC) plays a key role in sperm metabolism based on energy production (-oxidation) and reduction of lipid availability for peroxidation. In this sense, this research evaluated the effect of LC supplemented to two skimmed milk-based extenders on cryosurvival of chilled and frozen-thawed Peruvian Paso horse spermatozoa. A first experiment assessed the optimal LC dose (1, 5, 10, 25 and50 mM) added to INRA-96®-and UHT-extenders (plus 6% egg yolk) in 9 individual fresh and chilled for 96 h semen ejaculates. A second experiment evaluated the effect of LC added to extenders: INRA-96 or UHT, and INRA-Freeze®or UHT (plus 5% glycerol), in 16 ejaculatespooled (n=8 pools, 2 ejaculates/pool)either chilled or frozen, respectively. The results demonstrated that 25 mM LC, successfully preserved the kinetics and integrity of plasma and acrosomal membranes in individual samples of cold-stored equine semen for 48 and 96 h. In pooled samples, diluted with INRA (96 or Freeze) and supplemented with LC, the sperm characteristics were better maintained than UHT-extender up to 72 h of cold storage. After the freezing-thawed process, LC supplementation to INRA-Freeze extender improved motility and plasma membrane integrity, while the addition to UHT-extender improved acrosomal membrane integrity. In conclusion, the addition of L-carnitine to skimmed milk-based extenders has a positive effect on the kinetics and integrity of plasma and acrosomal membranes of chilled and frozen-thawed equine sperm.