Embryo development of bovine oocytes held in follicular fluid from bovine follicles of different diameters

Abstract

Bovine oocytes have been maintained in the follicular fluid to be transported and to increase their competence, before maturation. Eight hundred eighty-one (881) oocytes, aspirated from bovine slaughterhouse ovaries, were used to evaluate the effect of holding bovine oocytes in follicular fluid (FF) of bovine follicles of different diameters on the rate of embryo development. The oocytes were randomly distributed in four treatments with seven replicates each: The control group (n=217) was constituted by oocytes matured for 24h in modified TCM-199 with Estrus Mare Serum (EMS), pyruvate and rFSH-h in incubator with 5,00% CO2, 39°C and saturated humidity. In the FFsmall group (3 to 5mm follicles; n=216), the oocytes were held for 6h in follicular fluid at 30°C and matured for 18h in the same conditions of the Control-group. The oocytes of the FFmedium group (5,1-8mm follicles; n=226) and of the FFlarge group (>;8,1mm follicles; n=222) were held in follicular fluid and matured like FFsmall. Fertilization was accomplished during 18h and, after this, the zygotes were cultured for 8 days in SOFaaci medium + 5,00% EMS in incubator at 39°C using plastic bags gasified with 5,00%CO2, 5,00%O2 and 90,00%N2. FFsmall oocytes produced a lower (P;0,05) between the groups. Follicular fluid of medium and large follicles could be used to hold for 6h at 30°C bovine oocytes before their maturation for 18h.