DETERMINATION OF AN EFFECTIVE MEDIA AND ITS HORMONE AND PROTEIN SUPPLEMENTATION FOR IN VITRO MATURATION OF OOCYTES OF INDIGENOUS ZEBU COWS

Abstract

In vitro maturation (IVM) of oocytes is the first important step for successful in vitro embryo production of any mammalian species. The objectives of the present study were to determine an effective basic medium and its hormone and protein supplementation for IVM of oocytes of indigenous zebu cows. The oocytes were derived from ovaries of locally slaughtered cows after aspiration of follicle. The oocytes were cultured in medium for 24 hrs at 38.5ºC with 5% CO₂ in humidified air for maturation. The maturation of oocytes was evaluated by examining the presence of first polar body extrusion in denuded oocytes under inverted microscope. To determine an effective basic medium, the oocytes were cultured in fetal bovine serum (FBS) supplemented tissue culture medium (TCM), modified synthetic oviduct fluid (mSOF) and Tyrodes albumin lactate pyruvate (TALP) medium. The maturation rate was significantly higher (74±4.2) in TCM medium than that of TALP medium (58.2±6.2). To determine an effective hormone supplementation for maturation medium, the oocytes were cultured in either in follicle stimulating hormone (FSH) or gonadotrophin supplemented TCM. The maturation rate of oocytes was significantly (p>0.05) higher (73.3±4.0) in FSH supplemented medium than that of gonadotrophin supplemented counterpart (60.2±6.6). To determine an effective protein supplementation, the oocytes were cultured in FBS, oestrus cow serum (OCS) and bovine serum albumin (BSA) supplemented TCM 199. The maturation rate of oocytes were 73.0±5.9, 71.1±2.8, and 62.5±9.4 in medium supplemented with FBS, OCS and BSA respectively (p>0.05). In conclusions, TCM supplemented with either FBS, OCS or BSA as protein and FSH as hormone may be used as medium for IVM of oocytes of indigenous zebu cows.