Effect of Oocyte Diameter on In Vitro Fertilization in Iraqi local Goats

This study was conducted to investigate the association between the in vitro fertilization and the diameter of goat’s oocytes. Ovaries collected from a local abattoir and transported in normal saline within 1-2 hours after slaughter to the Theriogenology lab/College of Veterinary Medicine. The oocytes were collected by slicing method and classified on the basis of the nature of cumulus cells envelop oocytes. The selected oocytes (n = 534) were classified according to oocyte diameter into4 categories: <110, 110-125, 125-135 and >135µm.Each oocytes measured after excluding the zona pellucida and subjected to culture in TCM-199 improved with 10 IU/ml FSH, 10 IU/ml hCG and 1 μg/ml E2.Each category was cultured in TCM-199 to 24-28 hrs at 38 ͦ C. After the incubation period, these mature oocytes in each experimental group were assessed by protruding the first polar body. The percentage of oocytes that reached the MII stage was 7.5, 42.02,65.78 and 68.75%for the4 categories diameters of <110, 110-125, 125-135, >135µm respectively. The result of oocyte maturation was low in less diameter oocyte and high in large diameter oocyte. The mature oocyte fertilized by epididymal sperms after maturation and capacitation with heparin, after 24 hrs of incubation.The fertilization rates were estimated by protruding the second polar body or penetration sperms zona pellucid. The fertilization rate for each category was 0, 20.25, 34.66 and 40.25%respectively. In conclusion, there is a positive relationship between oocyte diameter and their maturation and fertilization.