This study aimed to evaluate the effect of adding insulin hormone at different levels (0, 5, 10 and 15 µg/ml) to maturation medium with or without exogenous hormones (FSH, LH and E17β) on the in vitro maturation (IVM) of rabbit oocytes. Total of 20 New Zealand White (NZW) rabbit does (5.5-6 mo of age and 2.5-3 kg LBW) were used as oocyte donors. Oocytes were recovered from ovaries of slaughtered does using slicing technique. All oocytes with evenly granulated dark ooplasm were matured in TCM-199 supplemented with 6% bovine serum albumin. Eight types of TCM-199, four types without and other four with exogenous hormones supplemented with insulin (0, 5, 10 and 15 µg /ml) were used. Oocytes were fixed and stained for examination after 18 h at 38.5°C, 5% CO2 and high humidity as a maturation period. Results showed significant (P<0.05) effect of insulin supplementation on IVM of rabbit oocyte only in terms of oocytes reaching MI, TI+MII and degenerated ones. Percentage of mature oocytes reaching MII was improved by all insulin levels as compared to un-supplemented media (42.1-44.6 vs. 34.1%), but the differences were not significant. Percentage of oocytes reaching both TI+MII increased (P<0.05) with insulin supplementation at a level of 5 µg/ml showing the best (P<0.05) improvement on oocyte maturation (51.0%) as compared to other insulin levels (45.5-47.6%) or the control medium (39.5%). Nuclear maturation of rabbit oocytes was not affected significantly when FSH, LH and E2 were deleted from the maturation medium, but Percentage of oocytes reaching both T1+MII stages was enhanced in the presence of hormones during the maturation period regardless of whether oocytes were treated with insulin or not. Maturation rate in term of oocytes reaching T1+MII was affected significantly (P<0.05) by the interaction between insulin and hormonal addition, reflecting improved percentage of oocytes reaching both T1+MII stages by addition of all insulin levels to hormone-TCM-199 medium. In this respect, insulin addition at a level of 5µg/ml showed the best result (58.7%). In conclusion, the present study demonstrated that the supplementation of the maturation medium with insulin improves the in vitro maturation rate of rabbit oocytes when oocytes are maturated in a defined maturation medium with or without hormones (FSH, LH and E2).

The present study aimed to evaluate some scrotal-testicular ultrasonography measurements in relation with semen quality of buffalo bulls at early ages. A total of 12 buffalo bull calves having 140-160 kg live body weight and aged 11-17 months were used in this study. Three ultrasonography examinations were performed at four age categories (11, 13, 15 and 17 mo) to estimate scrotal circumference (SC) and thickness of testicular mediastinum (MS) using B-mode ultrasound scanner. The testicular ultrasonograms were analyzed with the ultrasound machine using the spot metering technique, then mean pixel intensity values (PV, scale: 0-255) was calculated. Semen was collected at the same age categories and evaluated for ejaculate volume (EV), and percentage of mass motility (MM), dead sperm (DS) and abnormal sperm (AS) as well as sperm concentration (CN), then total sperm output (TSO) was calculated. Correlation coefficients for ultrasonography measurements and semen parameters were calculated. Results showed that SC, MS and PV were not affected significantly by age category, although there was a tendency of increase in SC and MS, and reduction in PV by increasing age category. EV and percentage of MM, DS and AS increased (P<0.05) by increasing age category, but all changes were significant (P<0.05) between 11 and 13 mo of age. SN showed an opposite trend of change, while TSO was not affected significantly by age category. There were insignificant differences in semen quality of bull calves with SC of ≤21or 22-30 cm, while semen quality was affected by both MS and PV. Bull calves having MS of >2 mm and PV of >141had better semen quality than those with ≤2 mm and ≤140 as MS and PV, respectively (P>0.05). The strongest correlation was positive between age and pixel value (r = 0.776, P<0.01).Based on the obtained results in the current study, it would be valuable to evidence the relationship between scrotal-testicular ultrasonography examination and future fertility based on developmental parameters measured in the young buffalo bull calves at early postpubertal ages.