The goal of this study was to evaluate the protective effect of egg yolk compared with a soybean lecithin-based extender on morphologic and functional characteristics of frozen bovine semen. The ejaculate of four bulls was divided into two equal parts, one diluted with egg-yolk-Tris extender (A) and the other with a soy-lecithin based extender (Andromed®) (B). In experiment I, five straws of extender A and B from each bull were thawed and assessed regarding motility (subjective and computerized analysis), vigor, concentration, sperm morphology and slow thermoresistance (STR), evaluation of membrane integrity through association of propidium iodite probes (PI), fluorescein isotiocianate - Pisum sativum (FITC-PSA) and lipophilic cationic carbocyanine (JC-1) and functional evaluation of the plasmatic membrane through Hyposmotic Swelling Test (HOST). An evaluation of chromatin integrity was performed with the acridine orange staining procedure. In experiment II, the frozen semen with different extenders was used for in vitro fertilization (IVF), analyzing cleavage rates and in vitro embryo development. No statistical difference between extenders was identified, suggesting that the soy lecithin extender may substitute egg-yolk-Tris extender, considering the individual variations of each bull used in this experiment.
bovine; soy lecithin; egg yolk; extender; embryos; in vitro fertilization and semen
