Royal jelly supplementation to synthetic and non-synthetic based-extenders helps maintain the motility and kinetics of chilled bull sperm for long-term

Royal Jelly (RJ) is a substantial nutrient produced by the hypopharynx and mandibular glands of worker bees from 4 to 11 days of age, and its composition is mainly based on water (60–70%), protein (27–41% ) and carbohydrates (30%), lipids (8–19%), vitamins (A, B, C, E), salts, and amino acids. Due to its composition, JR has been successfully used in sperm cryopreservation at concentrations from 0.2 to 1% (w/v) supplemented with synthetic base extenders (eg TRIS or TALP). Its effect has been evidenced in the increase of motility, viability, functionality of the plasmatic membrane and fertilizing capacity of fresh and cryopreserved ram sperm. Conventional freezing requires the use of penetrating cryoprotectants (eg glycerol) to prevent damage caused by ice crystal formation, however, vitrification requires high concentrations (0.1 to 6 M) of non-penetrating cryoprotectants (eg sucrose or trehalose) and rapid cooling, passing rapidly to the glass transition without forming ice crystals. This research evaluated the effect of JR (0.2%) supplemented to freezing (TCG-YH + 5% glycerol) and vitrification (TCG-YH + 100 mM sucrose) media on cryosurvival of bull sperm.