The objective of this study was to determine the efficacy of leptin supplementation into maturation medium on nuclear maturation and fertilization rate of sheep oocytes. The maturation process
was conducted using a tissue culture medium (TCM) 199 with four supplementation treatments of
leptin namely 0 (control), 10, 50, and 100 ng/mL. Fertilization was conducted in the oocytes supplemented with 10 ng/mL and control using 5×106
mL-1 spermatozoa. At the end of maturation and fertilization processes, the oocytes were stained with 2% aceto orcein to determine nuclear maturation rate
and pronuclear development. The results showed that the percentage of oocytes reaching metaphase
II (MII) stage significantly increased in the oocytes supplemented with leptin at a dose of 10 ng/mL
(P