Bovine ovaries fromNelore and crossbred cows (Experiment 1)were collected in an abattoir located
47km from the laboratory and transported in a 0.9% NaCl aqueous solution maintained between 30
and 37 ◦C in a thermocontainer. Arrival at the laboratory occurred less than 2 h after the collection of
the ovaries. Due to the scarce number of B. t. taurus cows available in our region, the ovaries used in
Experiment 2 were collected in an abattoir located 550km from our laboratory, and transported in
the same conditions as above. Ovaries arrived at the laboratory 6–7 h after collection at the abattoir.
Immature cumulus oocyte complexes (COC) were obtained by aspiration of 2–8mm follicles using
an 18-gauge needle attached to a 10-mL syringe. The follicular aspirations for Nelore and B. t. taurus
cows was conducted simultaneously, i.e., 6–7 h after collection of the ovaries. Therefore, for Nelore
breed the ovaries stayed in the laboratory (in the thermocontainer) for 4–5 h before follicle aspiration
(Experiment 2). The oocytes were classified according to their morphology