WHEAT germ(WG) was a rich source in antioxidants, and had antimicrobial effects also it proved to have anticold-shock effect in preservation of diluted semen. This study aimed to clarify how various types of wheat germ extracts (including oil, hydroethanolic, and water extracts) in combination with egg yolk contribute to the preservation of buck semen when subjected to the cooling procedure. WG was extracted with petroleum ether (for oil extract), hydroethanol extract and water extract. Chemical analysis of WG extracts was performed by Gas Chromatography to detect saturated and unsaturated fatty acids. Additionally, the antioxidant capacity and metal chelation and reducing power of the hydroethanolic extracts were determined. A pilot experiment was designed to choose the optimum best concentration among 5 concentrations (100-500 µg/ml increament). The concentrations of 200, 300 and 400 µg/ml tris-base were chosen for the study. Diluted semen samples were cooled at 4°C for 48 hours. Sperm motility, viability, abnormality, membrane and acrosome integrity were evaluated in chilled semen during the chilling period. The Malondialdehyde (MDA, nmol/ml) and Catalase (CAT, U/L), in diluted semen, were assessed after 48 hours of chilling. The best extract that conserved a high motile viable sperm with low lipid peroxidation and oxidative stress was the WG oil extract at a concentration of 200 and 300 µg/ml, with egg yolk addition. The WG oil extract was the best in most characteristics specially live sperm (86.33%), acrosome integrity (65.55%), hyperosmotic swelling test (HOST, 56.00%) and CAT (413.12 U/L), while, decrease in abnormal sperm (19.78%) and MDA (35.45 nmol/ml).  In conclusion, the use of wheat germ oil extract (200 to 300 µg/ml with less than 5% egg yolk) is suitable for preserving diluted rabbit buck semen for a period of 48 hours during the cooling process.