Daniele Missio

Superstimulation with eCG prior to ovum pick-up improves follicular development and fertilization rate of cattle oocytes

This study aimed to evaluate the effect of equine chorionic gonadotrophin (eCG) stimulation prior to ovum pick-up (OPU) on follicular development, number and quality of recovered oocytes, fertilization rate, and early embryo development in vitro. There were four OPU sessions (cross over) conducted on 16 Braford cows to evaluate the effect of various eCG doses. The timing of the wave of ovarian follicular development was synchronized, and three days after, the respective eCG dose was administrated (0, 200, 400, or 800 IU). The OPU was performed on Day 6, and viable oocytes were used for IVM and IVF according to the respective treatment. After IVF treatment, the fertilization and cleavage rates, time of cleavage, and the cell number at 48 h were evaluated. There was no difference in the number of follicles, oocyte quantity, and morphological quality of oocytes among treatments (P > 0.05). The oocyte recovery rate was similar among the eCG-treated groups, but was less than in the control group (P < 0.01). The eCG800 group, however, had a greater recovery rate of follicles >6 mm in diameter (P < 0.01). In addition, the eCG800 group had a greater rate of normal fertilization (P < 0.01) and lesser rate of polyspermy (P < 0.02). The cleavage rate of the eCG800 group was greater than the other treatment groups but similar to that of the control. In conclusion, the use of eCG800 increased the proportion of follicles > 6 mm, with improved rate of normal fertilization and reduced occurrence of polyspermy, without affecting early embryonic development in vitro.

Reduction in Percoll volume increases recovery rate of sex-sorted semen of bulls without affecting sperm quality and early embryonic development

The aim of the present study was to evaluate the effects of Percoll volume on recovery rate, sperm quality, and embryo development kinetics in in vitro production of cattle embryos. Straws of conventional and sex-sorted semen were allocated to three different volumes of Percoll: 300 μL of each Percoll gradient (90%, 60%, and 30%), Control; 100 μL of each Percoll gradient, P100; and 200 μL of each Percoll gradient, P200. Sperm quality, fertilization rate, and embryo morpho-kinetic development using time lapse cinematography up to 48 h post-insemination were evaluated. For conventionally processed semen, sperm motility, vigor, and recovery rate were greater in the P100 and P200 treatment groups compared to the Control (P < 0.05), whereas reactive oxygen species (ROS) concentrations, lipid peroxidation, and superoxide dismutase enzyme activity were not influenced by treatments. For sex-sorted semen, treatment with P100 increased sperm curvilinear velocity, average path velocity, and amplitude of lateral head displacement (P < 0.05). Recovery rate was greater in the P100 group than Control and P200 groups (P < 0.05), formation of ROS was less in the P100 than Control and P200 groups, and superoxide dismutase enzyme activity was less in the P100 than Control group. Fertilization and cleavage rates, time of first cleavage, and cell number were similar between the P100 and Control groups (P > 0.05). The inclusion of Percoll volumes of 100 μL resulted in an increased sperm recovery rate without damage to sperm quality or affecting early embryonic development.