Effects Of Royal Jelly on Nuclear Maturation, Fertilization and Culture of Bovine Oocytes

Abstract

The present study investigates the effects of royal jelly, which could be an alternative to serum replacement, on bovine oocyte maturation and embryo culture. Two experiments were designed for the effects of royal jelly on oocyte maturation (Experiment 1) and blastocyst development (Experiment 2). Ovaries, collected at a local abattoir, were transported to the laboratory in a flask. The selected oocytes were matured in bicarbonate-buffered Medium 199 containing Earle's salts supplemented with 10 % (v/v) foetal bovine serum or honeybee royal jelly (RJ; 1.25% w/v, RJ (1.25) and 0.625% w/v, RJ (0.625)) and antibiotics (50 IU/mL penicillin and 50 µg/mL streptomycin sulphate) under a humidified atmosphere of 5 % CO2 at 38 °C for 22-24 hours in Experiment 1. After maturation, oocytes were fertilised in fertilisation medium (TALP) supplemented with 6 mg/mL fatty acid-free BSA and 10 µg/mL heparin and following fertilization, presumptive zygotes were cultured in synthetic oviduct fluid (SOF) supplemented with %10 FBS for 8 days under a humidified atmosphere of 5% CO₂ 5% O₂ 90% N₂ at 38 °C in Experiment 2.

Royal jelly supplementation significantly (P< 0.05) reduced the number of third-class cumulus cells (FBS; 72.6%, RJ (1.25); 59.6%, and RJ (0.625); 63.8% of the group) compared with the serum used in Experiment 1. However, the results showed that supplementation of different concentrations of royal jelly in the maturation media did not affect the number of (MII) Metaphase II (FBS;77.6%, RJ (0.625); 71.5% and RJ (1.25); 64.3%) at the stage of nuclear maturation reached by the oocytes at the end of the maturation period in Experiment 1. The result also showed supplementation of royal jelly during the maturation period had no significant effect on the cleavage rates (FBS: 65.2% and RJ (0.625); 61.6 %) in Experiment 2. Royal jelly supplementation to the maturation medium had also no significant effect (P=0.09) on the morula stage (FBS; 29.5 % and RJ (0.625); 26.7 %) and (P > 0.05) on the blastocyst stage of the embryos (FBS; 20.6% and RJ (0.625); 18.7%). However, royal jelly supplementation to the maturation medium resulted in a decrease in blastocyst diameter and total cell counts.

As conclusion, the supplementation of 1.25% w/v and 0.625% w/v royal jelly to bovine oocyte maturation media reduced cumulus cells expansion but did not have negative effects on bovine oocyte maturation, fertilization, and blastocyst development. Therefore, the addition of royal jelly has some potential to be used as an alternative to serum for bovine oocytes during maturation.