Effect of melatonin supplementation during IVM of dromedary camel oocytes (Camelus dromedarius) on their maturation, fertilization, and developmental rates in vitro

The positive impact of melatonin on in vitro embryo production (IVEP) has been reported in many domestic species; however, no studies have been carried out in camelids. We aimed to evaluate the effects of melatonin supplementation in maturation media on in vitro maturation, fertilization, and preimplantation embryo development of dromedary camel oocytes (experiment 1). We also evaluated the concentrations of total antioxidant capacity (TAC), and malondialdehyde (MDA) in the IVM spent medium in relation to melatonin supplementation. Cumulus oocyte complexes (COCs) were cultured in in vitro maturation media (IVM) supplemented with either 0.0, 25.0, 50.0 or 75.0 μM of melatonin for 30 h. Matured oocytes were then fertilized in vitro with epididymal camel spermatozoa. Following IVF, the resulting embryos were cultured in vitro for seven days. The percentage of maturation, fertilization, cleavage, and embryo developmental rates (morula and blastocyst) was recorded (experiment 1). TAC and MDA levels in the IVM spent maturation media were also evaluated at 30 h post-IVM (experiment 2). The results showed that supplementation of IVM media with 25 μM melatonin significantly improved oocyte nuclear maturation, fertilization (18 h post-insemination; pi), cleavage (day 3 pi), morula (day 5 pi) and blastocyst (day 7 pi) rates as compared with the controls and other melatonin-supplemented groups. Furthermore, the TAC in the IVM spent media was significantly increased (P < 0.05) in 25 μM melatonin supplemented groups than those supplemented with 0.0, 50.0, 75.0 μM melatonin. However, the concentration of MDA was significantly lower (P < 0.05) in IVM media supplemented with 25.0 μM of melatonin when compared with the control and other treatment groups. In conclusion, supplementation of IVM medium with 25 μM of melatonin could enhance the in vitro developmental capacity of dromedary camel oocytes.