Royal Jelly improves the sperm parameters of ram semen during liquid storage and serves as an antioxidant source

Abstract

The current study was carried out to investigate the protective effects of the Royal Jelly (RJ) supplementation on the sperm kinematics, plasma membrane functionality, the level of produced nitric oxide (NO) and total antioxidant capacity during the liquid storage of ram semen at 4°C, for various periods of time (0, 24, 48, 72, 96 and 120h). Semen samples were collected from four rams and pooled, diluted with Tris–egg yolk extender without RJ (control) or supplemented with different concentrations of RJ (0, 0.5, 1, 1.5 and 2%), at a final concentration of 200×106sperm/mL. Sperm viability, kinematics and membrane functionality were determined by nigrosin–eosin staining, computer-assisted sperm analysis (CASA), and by using the hypo-osmotic swelling test (HOST), respectively. Additionally, the oxidative and nitrosative status were evaluated after the RJ supplementation. The RJ supplementation resulted in a significant (P<0.05) increase of sperm viability with the highest increase at 1% RJ concentration for 120h. A significant protective effect of RJ on sperm membrane functionality was obtained at lower concentrations (0.5 and 1%) and in all incubated time points. The most prominent protective effect of RJ on sperm motility parameters was found on the progressive velocity (VSL) as after 72h storage, no significant reduction was found in comparison to the 50% reduction in the control group. The produced NO level during storage time was reduced by addition of RJ at low concentrations (0.5 and 1%). Our data suggest that the RJ supplementation at lower concentrations (0.5 and 1%) improves the ram sperm kinetics and plasma membrane functionality during the liquid and cold storage. Moreover, the protective effect of RJ might be attributed to its antioxidative/antinitrosative capacities.